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Message-ID: <CAKTCnz=5wLq2OAKLfCOh5bX+t2T1exhhCdHUMkQchPzHNyU5Hw@mail.gmail.com>
Date: Tue, 27 Sep 2011 22:31:42 +0530
From: Balbir Singh <bsingharora@...il.com>
To: Glauber Costa <glommer@...allels.com>
Cc: linux-kernel@...r.kernel.org, paul@...lmenage.org,
lizf@...fujitsu.com, daniel.lezcano@...e.fr,
a.p.zijlstra@...llo.nl, jbottomley@...allels.com
Subject: Re: [RFD 3/9] Display /proc/stat information per cgroup
On Sat, Sep 24, 2011 at 3:50 AM, Glauber Costa <glommer@...allels.com> wrote:
> Each cgroup has its own file, cpu.proc.stat that will
> display the exact same format as /proc/stat. Users
> that want to have access to a per-cgroup version of
> this information, can query it for that purpose.
>
> Signed-off-by: Glauber Costa <glommer@...allels.com>
...
> +static inline void task_cgroup_account_field(struct task_struct *p,
> + cputime64_t tmp, int index)
> +{
> + struct kernel_stat *kstat;
> + struct task_group *tg = task_group(p);
> +
> + do {
> + kstat = this_cpu_ptr(tg->cpustat);
> + kstat->cpustat[index] = cputime64_add(kstat->cpustat[index],
> + tmp);
> + tg = tg->parent;
> + } while (tg);
> +}
What protects the walk (tg = tg->parent)? Could you please document it
> +
> /*
> * Account user cpu time to a process.
> * @p: the process that the cpu time gets accounted to
> @@ -3763,9 +3777,8 @@ unsigned long long thread_group_sched_runtime(struct task_struct *p)
> * @cputime_scaled: cputime scaled by cpu frequency
> */
> void account_user_time(struct task_struct *p, cputime_t cputime,
> - cputime_t cputime_scaled)
> + cputime_t cputime_scaled)
> {
> - cputime64_t *cpustat = kstat_this_cpu->cpustat;
> cputime64_t tmp;
>
> /* Add user time to process. */
> @@ -3775,10 +3788,11 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
>
> /* Add user time to cpustat. */
> tmp = cputime_to_cputime64(cputime);
> +
> if (TASK_NICE(p) > 0)
> - cpustat[NICE] = cputime64_add(cpustat[NICE], tmp);
> + task_cgroup_account_field(p, tmp, NICE);
> else
> - cpustat[USER] = cputime64_add(cpustat[USER], tmp);
> + task_cgroup_account_field(p, tmp, USER);
>
> cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
> /* Account for user time used */
> @@ -3824,7 +3838,7 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
> */
> static inline
> void __account_system_time(struct task_struct *p, cputime_t cputime,
> - cputime_t cputime_scaled, cputime64_t *target_cputime64)
> + cputime_t cputime_scaled, int index)
> {
> cputime64_t tmp = cputime_to_cputime64(cputime);
>
> @@ -3834,7 +3848,7 @@ void __account_system_time(struct task_struct *p, cputime_t cputime,
> account_group_system_time(p, cputime);
>
> /* Add system time to cpustat. */
> - *target_cputime64 = cputime64_add(*target_cputime64, tmp);
> + task_cgroup_account_field(p, tmp, index);
> cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
>
> /* Account for system time used */
> @@ -3851,8 +3865,7 @@ void __account_system_time(struct task_struct *p, cputime_t cputime,
> void account_system_time(struct task_struct *p, int hardirq_offset,
> cputime_t cputime, cputime_t cputime_scaled)
> {
> - cputime64_t *cpustat = kstat_this_cpu->cpustat;
> - cputime64_t *target_cputime64;
> + int index;
>
> if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
> account_guest_time(p, cputime, cputime_scaled);
> @@ -3860,13 +3873,13 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
> }
>
> if (hardirq_count() - hardirq_offset)
> - target_cputime64 = &cpustat[IRQ];
> + index = IRQ;
> else if (in_serving_softirq())
> - target_cputime64 = &cpustat[SOFTIRQ];
> + index = SOFTIRQ;
> else
> - target_cputime64 = &cpustat[SYSTEM];
> + index = SYSTEM;
>
> - __account_system_time(p, cputime, cputime_scaled, target_cputime64);
> + __account_system_time(p, cputime, cputime_scaled, index);
> }
>
> /*
> @@ -3941,27 +3954,29 @@ static __always_inline bool steal_account_process_tick(void)
> * softirq as those do not count in task exec_runtime any more.
> */
> static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
> - struct rq *rq)
> + struct rq *rq)
> {
> cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
> cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
> - cputime64_t *cpustat = kstat_this_cpu->cpustat;
> + struct task_group *tg;
>
> if (steal_account_process_tick())
> return;
>
> + tg = task_group(p);
> +
> if (irqtime_account_hi_update()) {
> - cpustat[IRQ] = cputime64_add(cpustat[IRQ], tmp);
> + task_cgroup_account_field(p, tmp, IRQ);
> } else if (irqtime_account_si_update()) {
> - cpustat[SOFTIRQ] = cputime64_add(cpustat[SOFTIRQ], tmp);
> + task_cgroup_account_field(p, tmp, SOFTIRQ);
> } else if (this_cpu_ksoftirqd() == p) {
> /*
> * ksoftirqd time do not get accounted in cpu_softirq_time.
> * So, we have to handle it separately here.
> * Also, p->stime needs to be updated for ksoftirqd.
> */
> - __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
> - &cpustat[SOFTIRQ]);
> + __account_system_time(p, cputime_one_jiffy,
> + one_jiffy_scaled, SOFTIRQ);
> } else if (user_tick) {
> account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
> } else if (p == rq->idle) {
> @@ -3969,8 +3984,8 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
> } else if (p->flags & PF_VCPU) { /* System time or guest time */
> account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
> } else {
> - __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
> - &cpustat[SYSTEM]);
> + __account_system_time(p, cputime_one_jiffy,
> + one_jiffy_scaled, SYSTEM);
> }
> }
>
> @@ -8038,6 +8053,7 @@ void __init sched_init(void)
> {
> int i, j;
> unsigned long alloc_size = 0, ptr;
> + struct kernel_stat *kstat;
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
> alloc_size += 2 * nr_cpu_ids * sizeof(void **);
> @@ -8092,6 +8108,18 @@ void __init sched_init(void)
> INIT_LIST_HEAD(&root_task_group.children);
> INIT_LIST_HEAD(&root_task_group.siblings);
> autogroup_init(&init_task);
> +
> + root_task_group.cpustat = alloc_percpu(struct kernel_stat);
> + /* Failing that early an allocation means we're screwed anyway */
> + BUG_ON(!root_task_group.cpustat);
> + for_each_possible_cpu(i) {
for_each_possible_cpu might be an overkill, no?
> + kstat = per_cpu_ptr(root_task_group.cpustat, i);
> + kstat->cpustat[IDLE] = 0;
> + kstat->cpustat[IDLE_BASE] = 0;
> + kstat->cpustat[IOWAIT_BASE] = 0;
> + kstat->cpustat[IOWAIT] = 0;
> + }
> +
> #endif /* CONFIG_CGROUP_SCHED */
>
> for_each_possible_cpu(i) {
> @@ -8526,6 +8554,7 @@ static void free_sched_group(struct task_group *tg)
> free_fair_sched_group(tg);
> free_rt_sched_group(tg);
> autogroup_free(tg);
> + free_percpu(tg->cpustat);
> kfree(tg);
> }
>
> @@ -8534,6 +8563,7 @@ struct task_group *sched_create_group(struct task_group *parent)
> {
> struct task_group *tg;
> unsigned long flags;
> + int i;
>
> tg = kzalloc(sizeof(*tg), GFP_KERNEL);
> if (!tg)
> @@ -8545,6 +8575,19 @@ struct task_group *sched_create_group(struct task_group *parent)
> if (!alloc_rt_sched_group(tg, parent))
> goto err;
>
> + tg->cpustat = alloc_percpu(struct kernel_stat);
> + if (!tg->cpustat)
> + goto err;
> +
> + for_each_possible_cpu(i) {
> + struct kernel_stat *kstat, *root_kstat;
> +
> + kstat = per_cpu_ptr(tg->cpustat, i);
> + root_kstat = per_cpu_ptr(root_task_group.cpustat, i);
> + kstat->cpustat[IDLE_BASE] = root_kstat->cpustat[IDLE];
> + kstat->cpustat[IOWAIT_BASE] = root_kstat->cpustat[IOWAIT];
> + }
> +
> spin_lock_irqsave(&task_group_lock, flags);
> list_add_rcu(&tg->list, &task_groups);
>
> @@ -9092,7 +9135,9 @@ int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft, struct seq_fil
> system = cputime64_add(system, kstat->cpustat[SYSTEM]);
> idle = cputime64_add(idle, root_kstat->cpustat[IDLE]);
> idle = cputime64_add(idle, arch_idle_time(i));
> + idle = cputime64_sub(idle, kstat->cpustat[IDLE_BASE]);
> iowait = cputime64_add(iowait, root_kstat->cpustat[IOWAIT]);
> + iowait = cputime64_sub(iowait, kstat->cpustat[IOWAIT_BASE]);
> irq = cputime64_add(irq, kstat->cpustat[IRQ]);
> softirq = cputime64_add(softirq, kstat->cpustat[SOFTIRQ]);
> steal = cputime64_add(steal, kstat->cpustat[STEAL]);
> @@ -9134,7 +9179,9 @@ int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft, struct seq_fil
> system = kstat->cpustat[SYSTEM];
> idle = root_kstat->cpustat[IDLE];
> idle = cputime64_add(idle, arch_idle_time(i));
> + idle = cputime64_sub(idle, kstat->cpustat[IDLE_BASE]);
> iowait = root_kstat->cpustat[IOWAIT];
> + iowait = cputime64_sub(iowait, kstat->cpustat[IOWAIT_BASE]);
> irq = kstat->cpustat[IRQ];
> softirq = kstat->cpustat[SOFTIRQ];
> steal = kstat->cpustat[STEAL];
> @@ -9205,6 +9252,10 @@ static struct cftype cpu_files[] = {
> .write_u64 = cpu_rt_period_write_uint,
> },
> #endif
> + {
> + .name = "proc.stat",
> + .read_seq_string = cpu_cgroup_proc_stat,
Looks fine to me
Balbir Singh
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