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a7c6d554aa
css (cgroup_subsys_state) is usually embedded in a subsys specific data structure. Subsystems either use container_of() directly to cast from css to such data structure or has an accessor function wrapping such cast. As cgroup as whole is moving towards using css as the main interface handle, add and update such accessors to ease dealing with css's. All accessors explicitly handle NULL input and return NULL in those cases. While this looks like an extra branch in the code, as all controllers specific data structures have css as the first field, the casting doesn't involve any offsetting and the compiler can trivially optimize out the branch. * blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such accessor. Added. * memory, hugetlb and devices already had one but didn't explicitly handle NULL input. Updated. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
300 lines
6.3 KiB
C
300 lines
6.3 KiB
C
#include <linux/cgroup.h>
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#include <linux/slab.h>
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#include <linux/percpu.h>
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#include <linux/spinlock.h>
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#include <linux/cpumask.h>
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#include <linux/seq_file.h>
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#include <linux/rcupdate.h>
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#include <linux/kernel_stat.h>
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#include <linux/err.h>
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#include "sched.h"
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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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/* 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 corresponding to this container */
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static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
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{
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return css_ca(cgroup_css(cgrp, cpuacct_subsys_id));
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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_subsys_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 cgroup_ca(ca->css.cgroup->parent);
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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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if (!ca->css.cgroup->parent)
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return NULL;
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return cgroup_ca(ca->css.cgroup->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 *cpuacct_css_alloc(struct cgroup *cgrp)
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{
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struct cpuacct *ca;
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if (!cgrp->parent)
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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 *cgrp)
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{
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struct cpuacct *ca = cgroup_ca(cgrp);
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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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{
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u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
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u64 data;
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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_lock_irq(&cpu_rq(cpu)->lock);
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data = *cpuusage;
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raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
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#else
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data = *cpuusage;
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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, u64 val)
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{
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u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
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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_lock_irq(&cpu_rq(cpu)->lock);
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*cpuusage = val;
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raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
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#else
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*cpuusage = val;
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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 *cgrp, struct cftype *cft)
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{
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struct cpuacct *ca = cgroup_ca(cgrp);
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u64 totalcpuusage = 0;
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int i;
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for_each_present_cpu(i)
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totalcpuusage += cpuacct_cpuusage_read(ca, i);
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return totalcpuusage;
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}
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static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
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u64 reset)
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{
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struct cpuacct *ca = cgroup_ca(cgrp);
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int err = 0;
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int i;
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if (reset) {
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err = -EINVAL;
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goto out;
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}
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for_each_present_cpu(i)
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cpuacct_cpuusage_write(ca, i, 0);
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out:
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return err;
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}
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static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
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struct seq_file *m)
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{
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struct cpuacct *ca = cgroup_ca(cgroup);
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u64 percpu;
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int i;
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for_each_present_cpu(i) {
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percpu = cpuacct_cpuusage_read(ca, i);
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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 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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static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
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struct cgroup_map_cb *cb)
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{
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struct cpuacct *ca = cgroup_ca(cgrp);
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int cpu;
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s64 val = 0;
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for_each_online_cpu(cpu) {
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struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
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val += kcpustat->cpustat[CPUTIME_USER];
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val += kcpustat->cpustat[CPUTIME_NICE];
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}
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val = cputime64_to_clock_t(val);
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cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val);
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val = 0;
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for_each_online_cpu(cpu) {
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struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
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val += kcpustat->cpustat[CPUTIME_SYSTEM];
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val += kcpustat->cpustat[CPUTIME_IRQ];
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val += kcpustat->cpustat[CPUTIME_SOFTIRQ];
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}
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val = cputime64_to_clock_t(val);
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cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val);
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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_percpu",
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.read_seq_string = cpuacct_percpu_seq_read,
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},
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{
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.name = "stat",
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.read_map = 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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struct cpuacct *ca;
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int cpu;
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cpu = task_cpu(tsk);
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rcu_read_lock();
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ca = task_ca(tsk);
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while (true) {
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u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
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*cpuusage += cputime;
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ca = parent_ca(ca);
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if (!ca)
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break;
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}
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rcu_read_unlock();
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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 *p, int index, u64 val)
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{
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struct kernel_cpustat *kcpustat;
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struct cpuacct *ca;
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rcu_read_lock();
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ca = task_ca(p);
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while (ca != &root_cpuacct) {
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kcpustat = this_cpu_ptr(ca->cpustat);
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kcpustat->cpustat[index] += val;
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ca = __parent_ca(ca);
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}
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rcu_read_unlock();
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}
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struct cgroup_subsys cpuacct_subsys = {
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.name = "cpuacct",
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.css_alloc = cpuacct_css_alloc,
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.css_free = cpuacct_css_free,
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.subsys_id = cpuacct_subsys_id,
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.base_cftypes = files,
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.early_init = 1,
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};
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