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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Ingo Molnar](/assets/img/avatar_default.png)
Merge the scheduler build speedup of the fast-headers tree. Cumulative scheduler (kernel/sched/) build time speedup on a Linux distribution's config, which enables all scheduler features, compared to the vanilla kernel: _____________________________________________________________________________ | | Vanilla kernel (v5.13-rc7): |_____________________________________________________________________________ | | Performance counter stats for 'make -j96 kernel/sched/' (3 runs): | | 126,975,564,374 instructions # 1.45 insn per cycle ( +- 0.00% ) | 87,637,847,671 cycles # 3.959 GHz ( +- 0.30% ) | 22,136.96 msec cpu-clock # 7.499 CPUs utilized ( +- 0.29% ) | | 2.9520 +- 0.0169 seconds time elapsed ( +- 0.57% ) |_____________________________________________________________________________ | | Patched kernel: |_____________________________________________________________________________ | | Performance counter stats for 'make -j96 kernel/sched/' (3 runs): | | 50,420,496,914 instructions # 1.47 insn per cycle ( +- 0.00% ) | 34,234,322,038 cycles # 3.946 GHz ( +- 0.31% ) | 8,675.81 msec cpu-clock # 3.053 CPUs utilized ( +- 0.45% ) | | 2.8420 +- 0.0181 seconds time elapsed ( +- 0.64% ) |_____________________________________________________________________________ Summary: - CPU time used to build the scheduler dropped by -60.9%, a reduction from 22.1 clock-seconds to 8.7 clock-seconds. - Wall-clock time to build the scheduler dropped by -3.9%, a reduction from 2.95 seconds to 2.84 seconds. Signed-off-by: Ingo Molnar <mingo@kernel.org>
363 lines
8.1 KiB
C
363 lines
8.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* CPU accounting code for task groups.
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*
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* Based on the work by Paul Menage (menage@google.com) and Balbir Singh
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* (balbir@in.ibm.com).
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*/
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/* Time spent by the tasks of the CPU accounting group executing in ... */
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enum cpuacct_stat_index {
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CPUACCT_STAT_USER, /* ... user mode */
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CPUACCT_STAT_SYSTEM, /* ... kernel mode */
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CPUACCT_STAT_NSTATS,
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};
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static const char * const cpuacct_stat_desc[] = {
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[CPUACCT_STAT_USER] = "user",
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[CPUACCT_STAT_SYSTEM] = "system",
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};
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/* track CPU usage of a group of tasks and its child groups */
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struct cpuacct {
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struct cgroup_subsys_state css;
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/* cpuusage holds pointer to a u64-type object on every CPU */
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u64 __percpu *cpuusage;
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struct kernel_cpustat __percpu *cpustat;
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};
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static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
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{
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return css ? container_of(css, struct cpuacct, css) : NULL;
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}
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/* Return CPU accounting group to which this task belongs */
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static inline struct cpuacct *task_ca(struct task_struct *tsk)
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{
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return css_ca(task_css(tsk, cpuacct_cgrp_id));
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}
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static inline struct cpuacct *parent_ca(struct cpuacct *ca)
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{
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return css_ca(ca->css.parent);
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}
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static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
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static struct cpuacct root_cpuacct = {
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.cpustat = &kernel_cpustat,
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.cpuusage = &root_cpuacct_cpuusage,
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};
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/* Create a new CPU accounting group */
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static struct cgroup_subsys_state *
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cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
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{
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struct cpuacct *ca;
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if (!parent_css)
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return &root_cpuacct.css;
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ca = kzalloc(sizeof(*ca), GFP_KERNEL);
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if (!ca)
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goto out;
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ca->cpuusage = alloc_percpu(u64);
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if (!ca->cpuusage)
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goto out_free_ca;
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ca->cpustat = alloc_percpu(struct kernel_cpustat);
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if (!ca->cpustat)
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goto out_free_cpuusage;
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return &ca->css;
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out_free_cpuusage:
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free_percpu(ca->cpuusage);
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out_free_ca:
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kfree(ca);
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out:
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return ERR_PTR(-ENOMEM);
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}
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/* Destroy an existing CPU accounting group */
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static void cpuacct_css_free(struct cgroup_subsys_state *css)
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{
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struct cpuacct *ca = css_ca(css);
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free_percpu(ca->cpustat);
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free_percpu(ca->cpuusage);
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kfree(ca);
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}
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static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
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enum cpuacct_stat_index index)
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{
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u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
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u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
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u64 data;
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/*
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* We allow index == CPUACCT_STAT_NSTATS here to read
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* the sum of usages.
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*/
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if (WARN_ON_ONCE(index > CPUACCT_STAT_NSTATS))
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return 0;
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#ifndef CONFIG_64BIT
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/*
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* Take rq->lock to make 64-bit read safe on 32-bit platforms.
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*/
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raw_spin_rq_lock_irq(cpu_rq(cpu));
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#endif
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switch (index) {
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case CPUACCT_STAT_USER:
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data = cpustat[CPUTIME_USER] + cpustat[CPUTIME_NICE];
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break;
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case CPUACCT_STAT_SYSTEM:
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data = cpustat[CPUTIME_SYSTEM] + cpustat[CPUTIME_IRQ] +
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cpustat[CPUTIME_SOFTIRQ];
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break;
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case CPUACCT_STAT_NSTATS:
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data = *cpuusage;
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break;
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}
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#ifndef CONFIG_64BIT
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raw_spin_rq_unlock_irq(cpu_rq(cpu));
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#endif
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return data;
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}
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static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu)
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{
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u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
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u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
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/* Don't allow to reset global kernel_cpustat */
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if (ca == &root_cpuacct)
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return;
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#ifndef CONFIG_64BIT
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/*
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* Take rq->lock to make 64-bit write safe on 32-bit platforms.
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*/
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raw_spin_rq_lock_irq(cpu_rq(cpu));
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#endif
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*cpuusage = 0;
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cpustat[CPUTIME_USER] = cpustat[CPUTIME_NICE] = 0;
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cpustat[CPUTIME_SYSTEM] = cpustat[CPUTIME_IRQ] = 0;
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cpustat[CPUTIME_SOFTIRQ] = 0;
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#ifndef CONFIG_64BIT
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raw_spin_rq_unlock_irq(cpu_rq(cpu));
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#endif
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}
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/* Return total CPU usage (in nanoseconds) of a group */
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static u64 __cpuusage_read(struct cgroup_subsys_state *css,
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enum cpuacct_stat_index index)
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{
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struct cpuacct *ca = css_ca(css);
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u64 totalcpuusage = 0;
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int i;
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for_each_possible_cpu(i)
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totalcpuusage += cpuacct_cpuusage_read(ca, i, index);
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return totalcpuusage;
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}
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static u64 cpuusage_user_read(struct cgroup_subsys_state *css,
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struct cftype *cft)
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{
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return __cpuusage_read(css, CPUACCT_STAT_USER);
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}
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static u64 cpuusage_sys_read(struct cgroup_subsys_state *css,
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struct cftype *cft)
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{
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return __cpuusage_read(css, CPUACCT_STAT_SYSTEM);
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}
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static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
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{
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return __cpuusage_read(css, CPUACCT_STAT_NSTATS);
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}
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static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
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u64 val)
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{
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struct cpuacct *ca = css_ca(css);
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int cpu;
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/*
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* Only allow '0' here to do a reset.
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*/
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if (val)
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return -EINVAL;
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for_each_possible_cpu(cpu)
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cpuacct_cpuusage_write(ca, cpu);
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return 0;
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}
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static int __cpuacct_percpu_seq_show(struct seq_file *m,
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enum cpuacct_stat_index index)
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{
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struct cpuacct *ca = css_ca(seq_css(m));
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u64 percpu;
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int i;
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for_each_possible_cpu(i) {
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percpu = cpuacct_cpuusage_read(ca, i, index);
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seq_printf(m, "%llu ", (unsigned long long) percpu);
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}
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seq_printf(m, "\n");
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return 0;
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}
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static int cpuacct_percpu_user_seq_show(struct seq_file *m, void *V)
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{
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return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_USER);
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}
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static int cpuacct_percpu_sys_seq_show(struct seq_file *m, void *V)
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{
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return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_SYSTEM);
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}
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static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
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{
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return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
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}
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static int cpuacct_all_seq_show(struct seq_file *m, void *V)
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{
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struct cpuacct *ca = css_ca(seq_css(m));
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int index;
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int cpu;
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seq_puts(m, "cpu");
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for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
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seq_printf(m, " %s", cpuacct_stat_desc[index]);
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seq_puts(m, "\n");
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for_each_possible_cpu(cpu) {
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seq_printf(m, "%d", cpu);
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for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
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seq_printf(m, " %llu",
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cpuacct_cpuusage_read(ca, cpu, index));
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seq_puts(m, "\n");
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}
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return 0;
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}
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static int cpuacct_stats_show(struct seq_file *sf, void *v)
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{
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struct cpuacct *ca = css_ca(seq_css(sf));
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struct task_cputime cputime;
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u64 val[CPUACCT_STAT_NSTATS];
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int cpu;
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int stat;
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memset(&cputime, 0, sizeof(cputime));
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for_each_possible_cpu(cpu) {
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u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
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cputime.utime += cpustat[CPUTIME_USER];
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cputime.utime += cpustat[CPUTIME_NICE];
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cputime.stime += cpustat[CPUTIME_SYSTEM];
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cputime.stime += cpustat[CPUTIME_IRQ];
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cputime.stime += cpustat[CPUTIME_SOFTIRQ];
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cputime.sum_exec_runtime += *per_cpu_ptr(ca->cpuusage, cpu);
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}
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cputime_adjust(&cputime, &seq_css(sf)->cgroup->prev_cputime,
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&val[CPUACCT_STAT_USER], &val[CPUACCT_STAT_SYSTEM]);
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for (stat = 0; stat < CPUACCT_STAT_NSTATS; stat++) {
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seq_printf(sf, "%s %llu\n", cpuacct_stat_desc[stat],
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nsec_to_clock_t(val[stat]));
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}
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return 0;
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}
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static struct cftype files[] = {
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{
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.name = "usage",
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.read_u64 = cpuusage_read,
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.write_u64 = cpuusage_write,
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},
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{
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.name = "usage_user",
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.read_u64 = cpuusage_user_read,
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},
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{
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.name = "usage_sys",
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.read_u64 = cpuusage_sys_read,
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},
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{
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.name = "usage_percpu",
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.seq_show = cpuacct_percpu_seq_show,
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},
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{
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.name = "usage_percpu_user",
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.seq_show = cpuacct_percpu_user_seq_show,
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},
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{
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.name = "usage_percpu_sys",
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.seq_show = cpuacct_percpu_sys_seq_show,
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},
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{
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.name = "usage_all",
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.seq_show = cpuacct_all_seq_show,
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},
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{
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.name = "stat",
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.seq_show = cpuacct_stats_show,
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},
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{ } /* terminate */
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};
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/*
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* charge this task's execution time to its accounting group.
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*
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* called with rq->lock held.
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*/
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void cpuacct_charge(struct task_struct *tsk, u64 cputime)
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{
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unsigned int cpu = task_cpu(tsk);
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struct cpuacct *ca;
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lockdep_assert_rq_held(cpu_rq(cpu));
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for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
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*per_cpu_ptr(ca->cpuusage, cpu) += cputime;
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}
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/*
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* Add user/system time to cpuacct.
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*
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* Note: it's the caller that updates the account of the root cgroup.
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*/
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void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
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{
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struct cpuacct *ca;
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for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
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__this_cpu_add(ca->cpustat->cpustat[index], val);
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}
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struct cgroup_subsys cpuacct_cgrp_subsys = {
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.css_alloc = cpuacct_css_alloc,
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.css_free = cpuacct_css_free,
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.legacy_cftypes = files,
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.early_init = true,
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};
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