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![Paul E. McKenney](/assets/img/avatar_default.png)
This commit adds three read-side-only tests of three use cases featuring SLAB_TYPESAFE_BY_RCU: One using per-object reference counting, one using per-object locking, and one using per-object sequence locking. [ paulmck: Apply feedback from kernel test robot. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
1138 lines
27 KiB
C
1138 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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//
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// Scalability test comparing RCU vs other mechanisms
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// for acquiring references on objects.
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//
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// Copyright (C) Google, 2020.
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//
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// Author: Joel Fernandes <joel@joelfernandes.org>
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#define pr_fmt(fmt) fmt
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#include <linux/atomic.h>
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#include <linux/bitops.h>
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#include <linux/completion.h>
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#include <linux/cpu.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/kthread.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/notifier.h>
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#include <linux/percpu.h>
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#include <linux/rcupdate.h>
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#include <linux/rcupdate_trace.h>
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#include <linux/reboot.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/stat.h>
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#include <linux/srcu.h>
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#include <linux/slab.h>
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#include <linux/torture.h>
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#include <linux/types.h>
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#include "rcu.h"
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#define SCALE_FLAG "-ref-scale: "
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#define SCALEOUT(s, x...) \
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pr_alert("%s" SCALE_FLAG s, scale_type, ## x)
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#define VERBOSE_SCALEOUT(s, x...) \
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do { \
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if (verbose) \
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pr_alert("%s" SCALE_FLAG s "\n", scale_type, ## x); \
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} while (0)
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static atomic_t verbose_batch_ctr;
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#define VERBOSE_SCALEOUT_BATCH(s, x...) \
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do { \
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if (verbose && \
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(verbose_batched <= 0 || \
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!(atomic_inc_return(&verbose_batch_ctr) % verbose_batched))) { \
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schedule_timeout_uninterruptible(1); \
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pr_alert("%s" SCALE_FLAG s "\n", scale_type, ## x); \
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} \
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} while (0)
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#define SCALEOUT_ERRSTRING(s, x...) pr_alert("%s" SCALE_FLAG "!!! " s "\n", scale_type, ## x)
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Joel Fernandes (Google) <joel@joelfernandes.org>");
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static char *scale_type = "rcu";
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module_param(scale_type, charp, 0444);
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MODULE_PARM_DESC(scale_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock.");
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torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
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torture_param(int, verbose_batched, 0, "Batch verbose debugging printk()s");
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// Wait until there are multiple CPUs before starting test.
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torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0,
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"Holdoff time before test start (s)");
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// Number of typesafe_lookup structures, that is, the degree of concurrency.
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torture_param(long, lookup_instances, 0, "Number of typesafe_lookup structures.");
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// Number of loops per experiment, all readers execute operations concurrently.
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torture_param(long, loops, 10000, "Number of loops per experiment.");
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// Number of readers, with -1 defaulting to about 75% of the CPUs.
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torture_param(int, nreaders, -1, "Number of readers, -1 for 75% of CPUs.");
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// Number of runs.
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torture_param(int, nruns, 30, "Number of experiments to run.");
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// Reader delay in nanoseconds, 0 for no delay.
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torture_param(int, readdelay, 0, "Read-side delay in nanoseconds.");
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#ifdef MODULE
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# define REFSCALE_SHUTDOWN 0
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#else
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# define REFSCALE_SHUTDOWN 1
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#endif
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torture_param(bool, shutdown, REFSCALE_SHUTDOWN,
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"Shutdown at end of scalability tests.");
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struct reader_task {
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struct task_struct *task;
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int start_reader;
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wait_queue_head_t wq;
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u64 last_duration_ns;
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};
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static struct task_struct *shutdown_task;
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static wait_queue_head_t shutdown_wq;
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static struct task_struct *main_task;
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static wait_queue_head_t main_wq;
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static int shutdown_start;
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static struct reader_task *reader_tasks;
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// Number of readers that are part of the current experiment.
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static atomic_t nreaders_exp;
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// Use to wait for all threads to start.
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static atomic_t n_init;
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static atomic_t n_started;
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static atomic_t n_warmedup;
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static atomic_t n_cooleddown;
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// Track which experiment is currently running.
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static int exp_idx;
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// Operations vector for selecting different types of tests.
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struct ref_scale_ops {
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bool (*init)(void);
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void (*cleanup)(void);
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void (*readsection)(const int nloops);
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void (*delaysection)(const int nloops, const int udl, const int ndl);
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const char *name;
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};
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static struct ref_scale_ops *cur_ops;
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static void un_delay(const int udl, const int ndl)
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{
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if (udl)
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udelay(udl);
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if (ndl)
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ndelay(ndl);
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}
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static void ref_rcu_read_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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rcu_read_lock();
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rcu_read_unlock();
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}
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}
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static void ref_rcu_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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rcu_read_lock();
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un_delay(udl, ndl);
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rcu_read_unlock();
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}
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}
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static bool rcu_sync_scale_init(void)
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{
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return true;
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}
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static struct ref_scale_ops rcu_ops = {
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.init = rcu_sync_scale_init,
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.readsection = ref_rcu_read_section,
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.delaysection = ref_rcu_delay_section,
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.name = "rcu"
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};
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// Definitions for SRCU ref scale testing.
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DEFINE_STATIC_SRCU(srcu_refctl_scale);
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static struct srcu_struct *srcu_ctlp = &srcu_refctl_scale;
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static void srcu_ref_scale_read_section(const int nloops)
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{
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int i;
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int idx;
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for (i = nloops; i >= 0; i--) {
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idx = srcu_read_lock(srcu_ctlp);
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srcu_read_unlock(srcu_ctlp, idx);
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}
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}
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static void srcu_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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int idx;
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for (i = nloops; i >= 0; i--) {
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idx = srcu_read_lock(srcu_ctlp);
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un_delay(udl, ndl);
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srcu_read_unlock(srcu_ctlp, idx);
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}
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}
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static struct ref_scale_ops srcu_ops = {
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.init = rcu_sync_scale_init,
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.readsection = srcu_ref_scale_read_section,
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.delaysection = srcu_ref_scale_delay_section,
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.name = "srcu"
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};
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#ifdef CONFIG_TASKS_RCU
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// Definitions for RCU Tasks ref scale testing: Empty read markers.
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// These definitions also work for RCU Rude readers.
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static void rcu_tasks_ref_scale_read_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--)
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continue;
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}
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static void rcu_tasks_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--)
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un_delay(udl, ndl);
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}
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static struct ref_scale_ops rcu_tasks_ops = {
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.init = rcu_sync_scale_init,
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.readsection = rcu_tasks_ref_scale_read_section,
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.delaysection = rcu_tasks_ref_scale_delay_section,
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.name = "rcu-tasks"
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};
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#define RCU_TASKS_OPS &rcu_tasks_ops,
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#else // #ifdef CONFIG_TASKS_RCU
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#define RCU_TASKS_OPS
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#endif // #else // #ifdef CONFIG_TASKS_RCU
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#ifdef CONFIG_TASKS_TRACE_RCU
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// Definitions for RCU Tasks Trace ref scale testing.
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static void rcu_trace_ref_scale_read_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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rcu_read_lock_trace();
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rcu_read_unlock_trace();
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}
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}
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static void rcu_trace_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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rcu_read_lock_trace();
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un_delay(udl, ndl);
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rcu_read_unlock_trace();
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}
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}
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static struct ref_scale_ops rcu_trace_ops = {
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.init = rcu_sync_scale_init,
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.readsection = rcu_trace_ref_scale_read_section,
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.delaysection = rcu_trace_ref_scale_delay_section,
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.name = "rcu-trace"
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};
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#define RCU_TRACE_OPS &rcu_trace_ops,
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#else // #ifdef CONFIG_TASKS_TRACE_RCU
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#define RCU_TRACE_OPS
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#endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
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// Definitions for reference count
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static atomic_t refcnt;
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static void ref_refcnt_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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atomic_inc(&refcnt);
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atomic_dec(&refcnt);
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}
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}
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static void ref_refcnt_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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atomic_inc(&refcnt);
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un_delay(udl, ndl);
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atomic_dec(&refcnt);
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}
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}
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static struct ref_scale_ops refcnt_ops = {
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.init = rcu_sync_scale_init,
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.readsection = ref_refcnt_section,
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.delaysection = ref_refcnt_delay_section,
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.name = "refcnt"
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};
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// Definitions for rwlock
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static rwlock_t test_rwlock;
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static bool ref_rwlock_init(void)
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{
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rwlock_init(&test_rwlock);
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return true;
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}
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static void ref_rwlock_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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read_lock(&test_rwlock);
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read_unlock(&test_rwlock);
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}
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}
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static void ref_rwlock_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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read_lock(&test_rwlock);
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un_delay(udl, ndl);
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read_unlock(&test_rwlock);
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}
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}
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static struct ref_scale_ops rwlock_ops = {
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.init = ref_rwlock_init,
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.readsection = ref_rwlock_section,
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.delaysection = ref_rwlock_delay_section,
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.name = "rwlock"
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};
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// Definitions for rwsem
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static struct rw_semaphore test_rwsem;
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static bool ref_rwsem_init(void)
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{
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init_rwsem(&test_rwsem);
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return true;
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}
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static void ref_rwsem_section(const int nloops)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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down_read(&test_rwsem);
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up_read(&test_rwsem);
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}
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}
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static void ref_rwsem_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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for (i = nloops; i >= 0; i--) {
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down_read(&test_rwsem);
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un_delay(udl, ndl);
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up_read(&test_rwsem);
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}
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}
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static struct ref_scale_ops rwsem_ops = {
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.init = ref_rwsem_init,
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.readsection = ref_rwsem_section,
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.delaysection = ref_rwsem_delay_section,
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.name = "rwsem"
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};
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// Definitions for global spinlock
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static DEFINE_RAW_SPINLOCK(test_lock);
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static void ref_lock_section(const int nloops)
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{
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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raw_spin_lock(&test_lock);
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raw_spin_unlock(&test_lock);
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}
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preempt_enable();
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}
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static void ref_lock_delay_section(const int nloops, const int udl, const int ndl)
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{
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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raw_spin_lock(&test_lock);
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un_delay(udl, ndl);
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raw_spin_unlock(&test_lock);
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}
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preempt_enable();
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}
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static struct ref_scale_ops lock_ops = {
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.readsection = ref_lock_section,
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.delaysection = ref_lock_delay_section,
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.name = "lock"
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};
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// Definitions for global irq-save spinlock
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static void ref_lock_irq_section(const int nloops)
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{
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unsigned long flags;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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raw_spin_lock_irqsave(&test_lock, flags);
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raw_spin_unlock_irqrestore(&test_lock, flags);
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}
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preempt_enable();
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}
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static void ref_lock_irq_delay_section(const int nloops, const int udl, const int ndl)
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{
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unsigned long flags;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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raw_spin_lock_irqsave(&test_lock, flags);
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un_delay(udl, ndl);
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raw_spin_unlock_irqrestore(&test_lock, flags);
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}
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preempt_enable();
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}
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static struct ref_scale_ops lock_irq_ops = {
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.readsection = ref_lock_irq_section,
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.delaysection = ref_lock_irq_delay_section,
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.name = "lock-irq"
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};
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// Definitions acquire-release.
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static DEFINE_PER_CPU(unsigned long, test_acqrel);
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static void ref_acqrel_section(const int nloops)
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{
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unsigned long x;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
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smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
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}
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preempt_enable();
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}
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static void ref_acqrel_delay_section(const int nloops, const int udl, const int ndl)
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{
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unsigned long x;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
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un_delay(udl, ndl);
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smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
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}
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preempt_enable();
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}
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static struct ref_scale_ops acqrel_ops = {
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.readsection = ref_acqrel_section,
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.delaysection = ref_acqrel_delay_section,
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.name = "acqrel"
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};
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static volatile u64 stopopts;
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static void ref_clock_section(const int nloops)
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{
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u64 x = 0;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--)
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x += ktime_get_real_fast_ns();
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preempt_enable();
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stopopts = x;
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}
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static void ref_clock_delay_section(const int nloops, const int udl, const int ndl)
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{
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u64 x = 0;
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int i;
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preempt_disable();
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for (i = nloops; i >= 0; i--) {
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x += ktime_get_real_fast_ns();
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un_delay(udl, ndl);
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}
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preempt_enable();
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stopopts = x;
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}
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static struct ref_scale_ops clock_ops = {
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.readsection = ref_clock_section,
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.delaysection = ref_clock_delay_section,
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.name = "clock"
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};
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////////////////////////////////////////////////////////////////////////
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//
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// Methods leveraging SLAB_TYPESAFE_BY_RCU.
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//
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// Item to look up in a typesafe manner. Array of pointers to these.
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struct refscale_typesafe {
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atomic_t rts_refctr; // Used by all flavors
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spinlock_t rts_lock;
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seqlock_t rts_seqlock;
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unsigned int a;
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unsigned int b;
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};
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static struct kmem_cache *typesafe_kmem_cachep;
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static struct refscale_typesafe **rtsarray;
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static long rtsarray_size;
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static DEFINE_TORTURE_RANDOM_PERCPU(refscale_rand);
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static bool (*rts_acquire)(struct refscale_typesafe *rtsp, unsigned int *start);
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static bool (*rts_release)(struct refscale_typesafe *rtsp, unsigned int start);
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// Conditionally acquire an explicit in-structure reference count.
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static bool typesafe_ref_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
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{
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return atomic_inc_not_zero(&rtsp->rts_refctr);
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}
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// Unconditionally release an explicit in-structure reference count.
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static bool typesafe_ref_release(struct refscale_typesafe *rtsp, unsigned int start)
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{
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if (!atomic_dec_return(&rtsp->rts_refctr)) {
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WRITE_ONCE(rtsp->a, rtsp->a + 1);
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kmem_cache_free(typesafe_kmem_cachep, rtsp);
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}
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return true;
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}
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// Unconditionally acquire an explicit in-structure spinlock.
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static bool typesafe_lock_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
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{
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spin_lock(&rtsp->rts_lock);
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return true;
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}
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// Unconditionally release an explicit in-structure spinlock.
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static bool typesafe_lock_release(struct refscale_typesafe *rtsp, unsigned int start)
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{
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spin_unlock(&rtsp->rts_lock);
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return true;
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}
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// Unconditionally acquire an explicit in-structure sequence lock.
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static bool typesafe_seqlock_acquire(struct refscale_typesafe *rtsp, unsigned int *start)
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{
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*start = read_seqbegin(&rtsp->rts_seqlock);
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return true;
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}
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// Conditionally release an explicit in-structure sequence lock. Return
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// true if this release was successful, that is, if no retry is required.
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static bool typesafe_seqlock_release(struct refscale_typesafe *rtsp, unsigned int start)
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{
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return !read_seqretry(&rtsp->rts_seqlock, start);
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}
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// Do a read-side critical section with the specified delay in
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// microseconds and nanoseconds inserted so as to increase probability
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// of failure.
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static void typesafe_delay_section(const int nloops, const int udl, const int ndl)
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{
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unsigned int a;
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unsigned int b;
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int i;
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long idx;
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struct refscale_typesafe *rtsp;
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unsigned int start;
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for (i = nloops; i >= 0; i--) {
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preempt_disable();
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idx = torture_random(this_cpu_ptr(&refscale_rand)) % rtsarray_size;
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preempt_enable();
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retry:
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rcu_read_lock();
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rtsp = rcu_dereference(rtsarray[idx]);
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a = READ_ONCE(rtsp->a);
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if (!rts_acquire(rtsp, &start)) {
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rcu_read_unlock();
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goto retry;
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}
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if (a != READ_ONCE(rtsp->a)) {
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(void)rts_release(rtsp, start);
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rcu_read_unlock();
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goto retry;
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}
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un_delay(udl, ndl);
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// Remember, seqlock read-side release can fail.
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if (!rts_release(rtsp, start)) {
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rcu_read_unlock();
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goto retry;
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}
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b = READ_ONCE(rtsp->a);
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WARN_ONCE(a != b, "Re-read of ->a changed from %u to %u.\n", a, b);
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b = rtsp->b;
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rcu_read_unlock();
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WARN_ON_ONCE(a * a != b);
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}
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}
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// Because the acquisition and release methods are expensive, there
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// is no point in optimizing away the un_delay() function's two checks.
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// Thus simply define typesafe_read_section() as a simple wrapper around
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// typesafe_delay_section().
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static void typesafe_read_section(const int nloops)
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{
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typesafe_delay_section(nloops, 0, 0);
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}
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// Allocate and initialize one refscale_typesafe structure.
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static struct refscale_typesafe *typesafe_alloc_one(void)
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{
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struct refscale_typesafe *rtsp;
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rtsp = kmem_cache_alloc(typesafe_kmem_cachep, GFP_KERNEL);
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if (!rtsp)
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return NULL;
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atomic_set(&rtsp->rts_refctr, 1);
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WRITE_ONCE(rtsp->a, rtsp->a + 1);
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WRITE_ONCE(rtsp->b, rtsp->a * rtsp->a);
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return rtsp;
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}
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// Slab-allocator constructor for refscale_typesafe structures created
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// out of a new slab of system memory.
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static void refscale_typesafe_ctor(void *rtsp_in)
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{
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struct refscale_typesafe *rtsp = rtsp_in;
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spin_lock_init(&rtsp->rts_lock);
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seqlock_init(&rtsp->rts_seqlock);
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preempt_disable();
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rtsp->a = torture_random(this_cpu_ptr(&refscale_rand));
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preempt_enable();
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}
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static struct ref_scale_ops typesafe_ref_ops;
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static struct ref_scale_ops typesafe_lock_ops;
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static struct ref_scale_ops typesafe_seqlock_ops;
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// Initialize for a typesafe test.
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static bool typesafe_init(void)
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{
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long idx;
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long si = lookup_instances;
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typesafe_kmem_cachep = kmem_cache_create("refscale_typesafe",
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sizeof(struct refscale_typesafe), sizeof(void *),
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SLAB_TYPESAFE_BY_RCU, refscale_typesafe_ctor);
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if (!typesafe_kmem_cachep)
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return false;
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if (si < 0)
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si = -si * nr_cpu_ids;
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else if (si == 0)
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si = nr_cpu_ids;
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rtsarray_size = si;
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rtsarray = kcalloc(si, sizeof(*rtsarray), GFP_KERNEL);
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if (!rtsarray)
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return false;
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for (idx = 0; idx < rtsarray_size; idx++) {
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rtsarray[idx] = typesafe_alloc_one();
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if (!rtsarray[idx])
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return false;
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}
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if (cur_ops == &typesafe_ref_ops) {
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rts_acquire = typesafe_ref_acquire;
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rts_release = typesafe_ref_release;
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} else if (cur_ops == &typesafe_lock_ops) {
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rts_acquire = typesafe_lock_acquire;
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rts_release = typesafe_lock_release;
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} else if (cur_ops == &typesafe_seqlock_ops) {
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rts_acquire = typesafe_seqlock_acquire;
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rts_release = typesafe_seqlock_release;
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} else {
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WARN_ON_ONCE(1);
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return false;
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}
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return true;
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}
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// Clean up after a typesafe test.
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static void typesafe_cleanup(void)
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{
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long idx;
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if (rtsarray) {
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for (idx = 0; idx < rtsarray_size; idx++)
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kmem_cache_free(typesafe_kmem_cachep, rtsarray[idx]);
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kfree(rtsarray);
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rtsarray = NULL;
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rtsarray_size = 0;
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}
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kmem_cache_destroy(typesafe_kmem_cachep);
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typesafe_kmem_cachep = NULL;
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rts_acquire = NULL;
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rts_release = NULL;
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}
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// The typesafe_init() function distinguishes these structures by address.
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static struct ref_scale_ops typesafe_ref_ops = {
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.init = typesafe_init,
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.cleanup = typesafe_cleanup,
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.readsection = typesafe_read_section,
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.delaysection = typesafe_delay_section,
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.name = "typesafe_ref"
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};
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static struct ref_scale_ops typesafe_lock_ops = {
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.init = typesafe_init,
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.cleanup = typesafe_cleanup,
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.readsection = typesafe_read_section,
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.delaysection = typesafe_delay_section,
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.name = "typesafe_lock"
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};
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static struct ref_scale_ops typesafe_seqlock_ops = {
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.init = typesafe_init,
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.cleanup = typesafe_cleanup,
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.readsection = typesafe_read_section,
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.delaysection = typesafe_delay_section,
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.name = "typesafe_seqlock"
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};
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static void rcu_scale_one_reader(void)
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{
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if (readdelay <= 0)
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cur_ops->readsection(loops);
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else
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cur_ops->delaysection(loops, readdelay / 1000, readdelay % 1000);
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}
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// Reader kthread. Repeatedly does empty RCU read-side
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// critical section, minimizing update-side interference.
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static int
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ref_scale_reader(void *arg)
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{
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unsigned long flags;
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long me = (long)arg;
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struct reader_task *rt = &(reader_tasks[me]);
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u64 start;
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s64 duration;
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VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: task started", me);
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WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)));
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set_user_nice(current, MAX_NICE);
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atomic_inc(&n_init);
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if (holdoff)
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schedule_timeout_interruptible(holdoff * HZ);
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repeat:
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VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, raw_smp_processor_id());
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|
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// Wait for signal that this reader can start.
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wait_event(rt->wq, (atomic_read(&nreaders_exp) && smp_load_acquire(&rt->start_reader)) ||
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torture_must_stop());
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if (torture_must_stop())
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goto end;
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// Make sure that the CPU is affinitized appropriately during testing.
|
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WARN_ON_ONCE(raw_smp_processor_id() != me);
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WRITE_ONCE(rt->start_reader, 0);
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if (!atomic_dec_return(&n_started))
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while (atomic_read_acquire(&n_started))
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cpu_relax();
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VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d started", me, exp_idx);
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// To reduce noise, do an initial cache-warming invocation, check
|
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// in, and then keep warming until everyone has checked in.
|
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rcu_scale_one_reader();
|
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if (!atomic_dec_return(&n_warmedup))
|
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while (atomic_read_acquire(&n_warmedup))
|
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rcu_scale_one_reader();
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// Also keep interrupts disabled. This also has the effect
|
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// of preventing entries into slow path for rcu_read_unlock().
|
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local_irq_save(flags);
|
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start = ktime_get_mono_fast_ns();
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|
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rcu_scale_one_reader();
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|
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duration = ktime_get_mono_fast_ns() - start;
|
|
local_irq_restore(flags);
|
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|
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rt->last_duration_ns = WARN_ON_ONCE(duration < 0) ? 0 : duration;
|
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// To reduce runtime-skew noise, do maintain-load invocations until
|
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// everyone is done.
|
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if (!atomic_dec_return(&n_cooleddown))
|
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while (atomic_read_acquire(&n_cooleddown))
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rcu_scale_one_reader();
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|
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if (atomic_dec_and_test(&nreaders_exp))
|
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wake_up(&main_wq);
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|
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VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)",
|
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me, exp_idx, atomic_read(&nreaders_exp));
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|
|
if (!torture_must_stop())
|
|
goto repeat;
|
|
end:
|
|
torture_kthread_stopping("ref_scale_reader");
|
|
return 0;
|
|
}
|
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|
|
static void reset_readers(void)
|
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{
|
|
int i;
|
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struct reader_task *rt;
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|
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for (i = 0; i < nreaders; i++) {
|
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rt = &(reader_tasks[i]);
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|
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rt->last_duration_ns = 0;
|
|
}
|
|
}
|
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|
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// Print the results of each reader and return the sum of all their durations.
|
|
static u64 process_durations(int n)
|
|
{
|
|
int i;
|
|
struct reader_task *rt;
|
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char buf1[64];
|
|
char *buf;
|
|
u64 sum = 0;
|
|
|
|
buf = kmalloc(800 + 64, GFP_KERNEL);
|
|
if (!buf)
|
|
return 0;
|
|
buf[0] = 0;
|
|
sprintf(buf, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)",
|
|
exp_idx);
|
|
|
|
for (i = 0; i < n && !torture_must_stop(); i++) {
|
|
rt = &(reader_tasks[i]);
|
|
sprintf(buf1, "%d: %llu\t", i, rt->last_duration_ns);
|
|
|
|
if (i % 5 == 0)
|
|
strcat(buf, "\n");
|
|
if (strlen(buf) >= 800) {
|
|
pr_alert("%s", buf);
|
|
buf[0] = 0;
|
|
}
|
|
strcat(buf, buf1);
|
|
|
|
sum += rt->last_duration_ns;
|
|
}
|
|
pr_alert("%s\n", buf);
|
|
|
|
kfree(buf);
|
|
return sum;
|
|
}
|
|
|
|
// The main_func is the main orchestrator, it performs a bunch of
|
|
// experiments. For every experiment, it orders all the readers
|
|
// involved to start and waits for them to finish the experiment. It
|
|
// then reads their timestamps and starts the next experiment. Each
|
|
// experiment progresses from 1 concurrent reader to N of them at which
|
|
// point all the timestamps are printed.
|
|
static int main_func(void *arg)
|
|
{
|
|
int exp, r;
|
|
char buf1[64];
|
|
char *buf;
|
|
u64 *result_avg;
|
|
|
|
set_cpus_allowed_ptr(current, cpumask_of(nreaders % nr_cpu_ids));
|
|
set_user_nice(current, MAX_NICE);
|
|
|
|
VERBOSE_SCALEOUT("main_func task started");
|
|
result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);
|
|
buf = kzalloc(800 + 64, GFP_KERNEL);
|
|
if (!result_avg || !buf) {
|
|
SCALEOUT_ERRSTRING("out of memory");
|
|
goto oom_exit;
|
|
}
|
|
if (holdoff)
|
|
schedule_timeout_interruptible(holdoff * HZ);
|
|
|
|
// Wait for all threads to start.
|
|
atomic_inc(&n_init);
|
|
while (atomic_read(&n_init) < nreaders + 1)
|
|
schedule_timeout_uninterruptible(1);
|
|
|
|
// Start exp readers up per experiment
|
|
for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
|
|
if (torture_must_stop())
|
|
goto end;
|
|
|
|
reset_readers();
|
|
atomic_set(&nreaders_exp, nreaders);
|
|
atomic_set(&n_started, nreaders);
|
|
atomic_set(&n_warmedup, nreaders);
|
|
atomic_set(&n_cooleddown, nreaders);
|
|
|
|
exp_idx = exp;
|
|
|
|
for (r = 0; r < nreaders; r++) {
|
|
smp_store_release(&reader_tasks[r].start_reader, 1);
|
|
wake_up(&reader_tasks[r].wq);
|
|
}
|
|
|
|
VERBOSE_SCALEOUT("main_func: experiment started, waiting for %d readers",
|
|
nreaders);
|
|
|
|
wait_event(main_wq,
|
|
!atomic_read(&nreaders_exp) || torture_must_stop());
|
|
|
|
VERBOSE_SCALEOUT("main_func: experiment ended");
|
|
|
|
if (torture_must_stop())
|
|
goto end;
|
|
|
|
result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
|
|
}
|
|
|
|
// Print the average of all experiments
|
|
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
|
|
|
|
pr_alert("Runs\tTime(ns)\n");
|
|
for (exp = 0; exp < nruns; exp++) {
|
|
u64 avg;
|
|
u32 rem;
|
|
|
|
avg = div_u64_rem(result_avg[exp], 1000, &rem);
|
|
sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
|
|
strcat(buf, buf1);
|
|
if (strlen(buf) >= 800) {
|
|
pr_alert("%s", buf);
|
|
buf[0] = 0;
|
|
}
|
|
}
|
|
|
|
pr_alert("%s", buf);
|
|
|
|
oom_exit:
|
|
// This will shutdown everything including us.
|
|
if (shutdown) {
|
|
shutdown_start = 1;
|
|
wake_up(&shutdown_wq);
|
|
}
|
|
|
|
// Wait for torture to stop us
|
|
while (!torture_must_stop())
|
|
schedule_timeout_uninterruptible(1);
|
|
|
|
end:
|
|
torture_kthread_stopping("main_func");
|
|
kfree(result_avg);
|
|
kfree(buf);
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
ref_scale_print_module_parms(struct ref_scale_ops *cur_ops, const char *tag)
|
|
{
|
|
pr_alert("%s" SCALE_FLAG
|
|
"--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag,
|
|
verbose, shutdown, holdoff, loops, nreaders, nruns, readdelay);
|
|
}
|
|
|
|
static void
|
|
ref_scale_cleanup(void)
|
|
{
|
|
int i;
|
|
|
|
if (torture_cleanup_begin())
|
|
return;
|
|
|
|
if (!cur_ops) {
|
|
torture_cleanup_end();
|
|
return;
|
|
}
|
|
|
|
if (reader_tasks) {
|
|
for (i = 0; i < nreaders; i++)
|
|
torture_stop_kthread("ref_scale_reader",
|
|
reader_tasks[i].task);
|
|
}
|
|
kfree(reader_tasks);
|
|
|
|
torture_stop_kthread("main_task", main_task);
|
|
kfree(main_task);
|
|
|
|
// Do scale-type-specific cleanup operations.
|
|
if (cur_ops->cleanup != NULL)
|
|
cur_ops->cleanup();
|
|
|
|
torture_cleanup_end();
|
|
}
|
|
|
|
// Shutdown kthread. Just waits to be awakened, then shuts down system.
|
|
static int
|
|
ref_scale_shutdown(void *arg)
|
|
{
|
|
wait_event(shutdown_wq, shutdown_start);
|
|
|
|
smp_mb(); // Wake before output.
|
|
ref_scale_cleanup();
|
|
kernel_power_off();
|
|
|
|
return -EINVAL;
|
|
}
|
|
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static int __init
|
|
ref_scale_init(void)
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{
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long i;
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int firsterr = 0;
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static struct ref_scale_ops *scale_ops[] = {
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&rcu_ops, &srcu_ops, RCU_TRACE_OPS RCU_TASKS_OPS &refcnt_ops, &rwlock_ops,
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&rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops,
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&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
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};
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if (!torture_init_begin(scale_type, verbose))
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return -EBUSY;
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for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
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cur_ops = scale_ops[i];
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if (strcmp(scale_type, cur_ops->name) == 0)
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break;
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}
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if (i == ARRAY_SIZE(scale_ops)) {
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pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
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pr_alert("rcu-scale types:");
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for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
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pr_cont(" %s", scale_ops[i]->name);
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pr_cont("\n");
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firsterr = -EINVAL;
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cur_ops = NULL;
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goto unwind;
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}
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if (cur_ops->init)
|
|
if (!cur_ops->init()) {
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|
firsterr = -EUCLEAN;
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|
goto unwind;
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|
}
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|
|
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ref_scale_print_module_parms(cur_ops, "Start of test");
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|
|
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// Shutdown task
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if (shutdown) {
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init_waitqueue_head(&shutdown_wq);
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firsterr = torture_create_kthread(ref_scale_shutdown, NULL,
|
|
shutdown_task);
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|
if (torture_init_error(firsterr))
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|
goto unwind;
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|
schedule_timeout_uninterruptible(1);
|
|
}
|
|
|
|
// Reader tasks (default to ~75% of online CPUs).
|
|
if (nreaders < 0)
|
|
nreaders = (num_online_cpus() >> 1) + (num_online_cpus() >> 2);
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|
if (WARN_ONCE(loops <= 0, "%s: loops = %ld, adjusted to 1\n", __func__, loops))
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loops = 1;
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if (WARN_ONCE(nreaders <= 0, "%s: nreaders = %d, adjusted to 1\n", __func__, nreaders))
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|
nreaders = 1;
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if (WARN_ONCE(nruns <= 0, "%s: nruns = %d, adjusted to 1\n", __func__, nruns))
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nruns = 1;
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|
reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]),
|
|
GFP_KERNEL);
|
|
if (!reader_tasks) {
|
|
SCALEOUT_ERRSTRING("out of memory");
|
|
firsterr = -ENOMEM;
|
|
goto unwind;
|
|
}
|
|
|
|
VERBOSE_SCALEOUT("Starting %d reader threads", nreaders);
|
|
|
|
for (i = 0; i < nreaders; i++) {
|
|
firsterr = torture_create_kthread(ref_scale_reader, (void *)i,
|
|
reader_tasks[i].task);
|
|
if (torture_init_error(firsterr))
|
|
goto unwind;
|
|
|
|
init_waitqueue_head(&(reader_tasks[i].wq));
|
|
}
|
|
|
|
// Main Task
|
|
init_waitqueue_head(&main_wq);
|
|
firsterr = torture_create_kthread(main_func, NULL, main_task);
|
|
if (torture_init_error(firsterr))
|
|
goto unwind;
|
|
|
|
torture_init_end();
|
|
return 0;
|
|
|
|
unwind:
|
|
torture_init_end();
|
|
ref_scale_cleanup();
|
|
if (shutdown) {
|
|
WARN_ON(!IS_MODULE(CONFIG_RCU_REF_SCALE_TEST));
|
|
kernel_power_off();
|
|
}
|
|
return firsterr;
|
|
}
|
|
|
|
module_init(ref_scale_init);
|
|
module_exit(ref_scale_cleanup);
|