linux-stable/arch/powerpc/kernel/smp.c
Paul Mackerras cf9efce0ce powerpc: Account time using timebase rather than PURR
Currently, when CONFIG_VIRT_CPU_ACCOUNTING is enabled, we use the
PURR register for measuring the user and system time used by
processes, as well as other related times such as hardirq and
softirq times.  This turns out to be quite confusing for users
because it means that a program will often be measured as taking
less time when run on a multi-threaded processor (SMT2 or SMT4 mode)
than it does when run on a single-threaded processor (ST mode), even
though the program takes longer to finish.  The discrepancy is
accounted for as stolen time, which is also confusing, particularly
when there are no other partitions running.

This changes the accounting to use the timebase instead, meaning that
the reported user and system times are the actual number of real-time
seconds that the program was executing on the processor thread,
regardless of which SMT mode the processor is in.  Thus a program will
generally show greater user and system times when run on a
multi-threaded processor than on a single-threaded processor.

On pSeries systems on POWER5 or later processors, we measure the
stolen time (time when this partition wasn't running) using the
hypervisor dispatch trace log.  We check for new entries in the
log on every entry from user mode and on every transition from
kernel process context to soft or hard IRQ context (i.e. when
account_system_vtime() gets called).  So that we can correctly
distinguish time stolen from user time and time stolen from system
time, without having to check the log on every exit to user mode,
we store separate timestamps for exit to user mode and entry from
user mode.

On systems that have a SPURR (POWER6 and POWER7), we read the SPURR
in account_system_vtime() (as before), and then apportion the SPURR
ticks since the last time we read it between scaled user time and
scaled system time according to the relative proportions of user
time and system time over the same interval.  This avoids having to
read the SPURR on every kernel entry and exit.  On systems that have
PURR but not SPURR (i.e., POWER5), we do the same using the PURR
rather than the SPURR.

This disables the DTL user interface in /sys/debug/kernel/powerpc/dtl
for now since it conflicts with the use of the dispatch trace log
by the time accounting code.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-09-02 14:07:31 +10:00

651 lines
14 KiB
C

/*
* SMP support for ppc.
*
* Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
* deal of code from the sparc and intel versions.
*
* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
*
* PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and
* Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/topology.h>
#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputhreads.h>
#include <asm/cputable.h>
#include <asm/system.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#endif
#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
struct thread_info *secondary_ti;
DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
EXPORT_PER_CPU_SYMBOL(cpu_core_map);
/* SMP operations for this machine */
struct smp_ops_t *smp_ops;
/* Can't be static due to PowerMac hackery */
volatile unsigned int cpu_callin_map[NR_CPUS];
int smt_enabled_at_boot = 1;
static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
#ifdef CONFIG_PPC64
void __devinit smp_generic_kick_cpu(int nr)
{
BUG_ON(nr < 0 || nr >= NR_CPUS);
/*
* The processor is currently spinning, waiting for the
* cpu_start field to become non-zero After we set cpu_start,
* the processor will continue on to secondary_start
*/
paca[nr].cpu_start = 1;
smp_mb();
}
#endif
void smp_message_recv(int msg)
{
switch(msg) {
case PPC_MSG_CALL_FUNCTION:
generic_smp_call_function_interrupt();
break;
case PPC_MSG_RESCHEDULE:
/* we notice need_resched on exit */
break;
case PPC_MSG_CALL_FUNC_SINGLE:
generic_smp_call_function_single_interrupt();
break;
case PPC_MSG_DEBUGGER_BREAK:
if (crash_ipi_function_ptr) {
crash_ipi_function_ptr(get_irq_regs());
break;
}
#ifdef CONFIG_DEBUGGER
debugger_ipi(get_irq_regs());
break;
#endif /* CONFIG_DEBUGGER */
/* FALLTHROUGH */
default:
printk("SMP %d: smp_message_recv(): unknown msg %d\n",
smp_processor_id(), msg);
break;
}
}
static irqreturn_t call_function_action(int irq, void *data)
{
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}
static irqreturn_t reschedule_action(int irq, void *data)
{
/* we just need the return path side effect of checking need_resched */
return IRQ_HANDLED;
}
static irqreturn_t call_function_single_action(int irq, void *data)
{
generic_smp_call_function_single_interrupt();
return IRQ_HANDLED;
}
static irqreturn_t debug_ipi_action(int irq, void *data)
{
smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
return IRQ_HANDLED;
}
static irq_handler_t smp_ipi_action[] = {
[PPC_MSG_CALL_FUNCTION] = call_function_action,
[PPC_MSG_RESCHEDULE] = reschedule_action,
[PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
[PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
};
const char *smp_ipi_name[] = {
[PPC_MSG_CALL_FUNCTION] = "ipi call function",
[PPC_MSG_RESCHEDULE] = "ipi reschedule",
[PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
[PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
};
/* optional function to request ipi, for controllers with >= 4 ipis */
int smp_request_message_ipi(int virq, int msg)
{
int err;
if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
return -EINVAL;
}
#if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
if (msg == PPC_MSG_DEBUGGER_BREAK) {
return 1;
}
#endif
err = request_irq(virq, smp_ipi_action[msg], IRQF_DISABLED|IRQF_PERCPU,
smp_ipi_name[msg], 0);
WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
virq, smp_ipi_name[msg], err);
return err;
}
void smp_send_reschedule(int cpu)
{
if (likely(smp_ops))
smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
}
void arch_send_call_function_single_ipi(int cpu)
{
smp_ops->message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
}
void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
unsigned int cpu;
for_each_cpu(cpu, mask)
smp_ops->message_pass(cpu, PPC_MSG_CALL_FUNCTION);
}
#ifdef CONFIG_DEBUGGER
void smp_send_debugger_break(int cpu)
{
if (likely(smp_ops))
smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
}
#endif
#ifdef CONFIG_KEXEC
void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
{
crash_ipi_function_ptr = crash_ipi_callback;
if (crash_ipi_callback && smp_ops) {
mb();
smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_DEBUGGER_BREAK);
}
}
#endif
static void stop_this_cpu(void *dummy)
{
/* Remove this CPU */
set_cpu_online(smp_processor_id(), false);
local_irq_disable();
while (1)
;
}
void smp_send_stop(void)
{
smp_call_function(stop_this_cpu, NULL, 0);
}
struct thread_info *current_set[NR_CPUS];
static void __devinit smp_store_cpu_info(int id)
{
per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
}
static void __init smp_create_idle(unsigned int cpu)
{
struct task_struct *p;
/* create a process for the processor */
p = fork_idle(cpu);
if (IS_ERR(p))
panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
#ifdef CONFIG_PPC64
paca[cpu].__current = p;
paca[cpu].kstack = (unsigned long) task_thread_info(p)
+ THREAD_SIZE - STACK_FRAME_OVERHEAD;
#endif
current_set[cpu] = task_thread_info(p);
task_thread_info(p)->cpu = cpu;
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
unsigned int cpu;
DBG("smp_prepare_cpus\n");
/*
* setup_cpu may need to be called on the boot cpu. We havent
* spun any cpus up but lets be paranoid.
*/
BUG_ON(boot_cpuid != smp_processor_id());
/* Fixup boot cpu */
smp_store_cpu_info(boot_cpuid);
cpu_callin_map[boot_cpuid] = 1;
for_each_possible_cpu(cpu) {
zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
GFP_KERNEL, cpu_to_node(cpu));
zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
GFP_KERNEL, cpu_to_node(cpu));
}
cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
if (smp_ops)
if (smp_ops->probe)
max_cpus = smp_ops->probe();
else
max_cpus = NR_CPUS;
else
max_cpus = 1;
for_each_possible_cpu(cpu)
if (cpu != boot_cpuid)
smp_create_idle(cpu);
}
void __devinit smp_prepare_boot_cpu(void)
{
BUG_ON(smp_processor_id() != boot_cpuid);
#ifdef CONFIG_PPC64
paca[boot_cpuid].__current = current;
#endif
current_set[boot_cpuid] = task_thread_info(current);
}
#ifdef CONFIG_HOTPLUG_CPU
/* State of each CPU during hotplug phases */
DEFINE_PER_CPU(int, cpu_state) = { 0 };
int generic_cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
if (cpu == boot_cpuid)
return -EBUSY;
set_cpu_online(cpu, false);
#ifdef CONFIG_PPC64
vdso_data->processorCount--;
fixup_irqs(cpu_online_mask);
#endif
return 0;
}
int generic_cpu_enable(unsigned int cpu)
{
/* Do the normal bootup if we haven't
* already bootstrapped. */
if (system_state != SYSTEM_RUNNING)
return -ENOSYS;
/* get the target out of it's holding state */
per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
smp_wmb();
while (!cpu_online(cpu))
cpu_relax();
#ifdef CONFIG_PPC64
fixup_irqs(cpu_online_mask);
/* counter the irq disable in fixup_irqs */
local_irq_enable();
#endif
return 0;
}
void generic_cpu_die(unsigned int cpu)
{
int i;
for (i = 0; i < 100; i++) {
smp_rmb();
if (per_cpu(cpu_state, cpu) == CPU_DEAD)
return;
msleep(100);
}
printk(KERN_ERR "CPU%d didn't die...\n", cpu);
}
void generic_mach_cpu_die(void)
{
unsigned int cpu;
local_irq_disable();
cpu = smp_processor_id();
printk(KERN_DEBUG "CPU%d offline\n", cpu);
__get_cpu_var(cpu_state) = CPU_DEAD;
smp_wmb();
while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
cpu_relax();
set_cpu_online(cpu, true);
local_irq_enable();
}
#endif
static int __devinit cpu_enable(unsigned int cpu)
{
if (smp_ops && smp_ops->cpu_enable)
return smp_ops->cpu_enable(cpu);
return -ENOSYS;
}
int __cpuinit __cpu_up(unsigned int cpu)
{
int c;
secondary_ti = current_set[cpu];
if (!cpu_enable(cpu))
return 0;
if (smp_ops == NULL ||
(smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
return -EINVAL;
/* Make sure callin-map entry is 0 (can be leftover a CPU
* hotplug
*/
cpu_callin_map[cpu] = 0;
/* The information for processor bringup must
* be written out to main store before we release
* the processor.
*/
smp_mb();
/* wake up cpus */
DBG("smp: kicking cpu %d\n", cpu);
smp_ops->kick_cpu(cpu);
/*
* wait to see if the cpu made a callin (is actually up).
* use this value that I found through experimentation.
* -- Cort
*/
if (system_state < SYSTEM_RUNNING)
for (c = 50000; c && !cpu_callin_map[cpu]; c--)
udelay(100);
#ifdef CONFIG_HOTPLUG_CPU
else
/*
* CPUs can take much longer to come up in the
* hotplug case. Wait five seconds.
*/
for (c = 5000; c && !cpu_callin_map[cpu]; c--)
msleep(1);
#endif
if (!cpu_callin_map[cpu]) {
printk(KERN_ERR "Processor %u is stuck.\n", cpu);
return -ENOENT;
}
DBG("Processor %u found.\n", cpu);
if (smp_ops->give_timebase)
smp_ops->give_timebase();
/* Wait until cpu puts itself in the online map */
while (!cpu_online(cpu))
cpu_relax();
return 0;
}
/* Return the value of the reg property corresponding to the given
* logical cpu.
*/
int cpu_to_core_id(int cpu)
{
struct device_node *np;
const int *reg;
int id = -1;
np = of_get_cpu_node(cpu, NULL);
if (!np)
goto out;
reg = of_get_property(np, "reg", NULL);
if (!reg)
goto out;
id = *reg;
out:
of_node_put(np);
return id;
}
/* Must be called when no change can occur to cpu_present_mask,
* i.e. during cpu online or offline.
*/
static struct device_node *cpu_to_l2cache(int cpu)
{
struct device_node *np;
struct device_node *cache;
if (!cpu_present(cpu))
return NULL;
np = of_get_cpu_node(cpu, NULL);
if (np == NULL)
return NULL;
cache = of_find_next_cache_node(np);
of_node_put(np);
return cache;
}
/* Activate a secondary processor. */
int __devinit start_secondary(void *unused)
{
unsigned int cpu = smp_processor_id();
struct device_node *l2_cache;
int i, base;
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
smp_store_cpu_info(cpu);
set_dec(tb_ticks_per_jiffy);
preempt_disable();
cpu_callin_map[cpu] = 1;
if (smp_ops->setup_cpu)
smp_ops->setup_cpu(cpu);
if (smp_ops->take_timebase)
smp_ops->take_timebase();
secondary_cpu_time_init();
ipi_call_lock();
notify_cpu_starting(cpu);
set_cpu_online(cpu, true);
/* Update sibling maps */
base = cpu_first_thread_in_core(cpu);
for (i = 0; i < threads_per_core; i++) {
if (cpu_is_offline(base + i))
continue;
cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
/* cpu_core_map should be a superset of
* cpu_sibling_map even if we don't have cache
* information, so update the former here, too.
*/
cpumask_set_cpu(cpu, cpu_core_mask(base + i));
cpumask_set_cpu(base + i, cpu_core_mask(cpu));
}
l2_cache = cpu_to_l2cache(cpu);
for_each_online_cpu(i) {
struct device_node *np = cpu_to_l2cache(i);
if (!np)
continue;
if (np == l2_cache) {
cpumask_set_cpu(cpu, cpu_core_mask(i));
cpumask_set_cpu(i, cpu_core_mask(cpu));
}
of_node_put(np);
}
of_node_put(l2_cache);
ipi_call_unlock();
local_irq_enable();
cpu_idle();
return 0;
}
int setup_profiling_timer(unsigned int multiplier)
{
return 0;
}
void __init smp_cpus_done(unsigned int max_cpus)
{
cpumask_var_t old_mask;
/* We want the setup_cpu() here to be called from CPU 0, but our
* init thread may have been "borrowed" by another CPU in the meantime
* se we pin us down to CPU 0 for a short while
*/
alloc_cpumask_var(&old_mask, GFP_NOWAIT);
cpumask_copy(old_mask, &current->cpus_allowed);
set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
if (smp_ops && smp_ops->setup_cpu)
smp_ops->setup_cpu(boot_cpuid);
set_cpus_allowed_ptr(current, old_mask);
free_cpumask_var(old_mask);
dump_numa_cpu_topology();
}
int arch_sd_sibling_asym_packing(void)
{
if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
return SD_ASYM_PACKING;
}
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
struct device_node *l2_cache;
int cpu = smp_processor_id();
int base, i;
int err;
if (!smp_ops->cpu_disable)
return -ENOSYS;
err = smp_ops->cpu_disable();
if (err)
return err;
/* Update sibling maps */
base = cpu_first_thread_in_core(cpu);
for (i = 0; i < threads_per_core; i++) {
cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
}
l2_cache = cpu_to_l2cache(cpu);
for_each_present_cpu(i) {
struct device_node *np = cpu_to_l2cache(i);
if (!np)
continue;
if (np == l2_cache) {
cpumask_clear_cpu(cpu, cpu_core_mask(i));
cpumask_clear_cpu(i, cpu_core_mask(cpu));
}
of_node_put(np);
}
of_node_put(l2_cache);
return 0;
}
void __cpu_die(unsigned int cpu)
{
if (smp_ops->cpu_die)
smp_ops->cpu_die(cpu);
}
static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
void cpu_hotplug_driver_lock()
{
mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
}
void cpu_hotplug_driver_unlock()
{
mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
}
void cpu_die(void)
{
if (ppc_md.cpu_die)
ppc_md.cpu_die();
}
#endif