On Thu, 12 Mar 2009 16:39:24 +0530 Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> wrote: > Here is the 2nd version of the cpuacct statistics patch. Copying > linux-arch list also this time to check if archs which define > CONFIG_VIRT_CPU_ACCOUNTING are ok with this change. > > Changes for v2: > - stime and utime now exported in clock_t units instead of msecs. > - Addressed the code review comments from Balbir and Li Zefan. > - Moved to -tip tree. > > v1: > - http://lkml.org/lkml/2009/3/10/150 > > > cpuacct: Add stime and utime statistics > > Add per-cgroup cpuacct controller statistics like the system and user > time consumed by the group of tasks. > > Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Balaji Rao <balajirrao@xxxxxxxxx> > --- > Documentation/cgroups/cpuacct.txt | 17 +++++++ > kernel/sched.c | 86 +++++++++++++++++++++++++++++++++++--- > 2 files changed, 97 insertions(+), 6 deletions(-) > > --- a/Documentation/cgroups/cpuacct.txt > +++ b/Documentation/cgroups/cpuacct.txt > @@ -30,3 +30,20 @@ The above steps create a new group g1 an > process (bash) into it. CPU time consumed by this bash and its children > can be obtained from g1/cpuacct.usage and the same is accumulated in > /cgroups/cpuacct.usage also. > + > +cpuacct.stat file lists a few statistics which further divide the > +CPU time obtained by the cgroup into user and system times. Currently > +the following statistics are supported: > + > +utime: Time spent by tasks of the cgroup in user mode. > +stime: Time spent by tasks of the cgroup in kernel mode. > + > +utime and stime are in USER_HZ unit. > + > +cpuacct controller uses percpu_counter interface to collect utime and > +stime. This causes two side effects: > + > +- It is theoritically possible to see wrong values for stime and utime. > + This is because percpu_counter_read() on 32bit systems is broken. > +- It is possible to see slightly outdated values for stime and utime > + due to the batch processing nature of percpu_counter. > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -1434,10 +1434,22 @@ iter_move_one_task(struct rq *this_rq, i > struct rq_iterator *iterator); > #endif > > +/* Time spent by the tasks of the cpu accounting group executing in ... */ > +enum cpuacct_stat_index { > + CPUACCT_STAT_UTIME, /* ... user mode */ > + CPUACCT_STAT_STIME, /* ... kernel mode */ > + > + CPUACCT_STAT_NSTATS, > +}; > + > #ifdef CONFIG_CGROUP_CPUACCT > static void cpuacct_charge(struct task_struct *tsk, u64 cputime); > +static void cpuacct_update_stats(struct task_struct *tsk, > + enum cpuacct_stat_index idx, cputime_t val); > #else > static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {} > +static void cpuacct_update_stats(struct task_struct *tsk, > + enum cpuacct_stat_index idx, cputime_t val) {} > #endif "static inline" if no "inline", the complier will show warning as "this function is defined but not used.." > static inline void inc_cpu_load(struct rq *rq, unsigned long load) > @@ -4379,6 +4391,8 @@ void account_user_time(struct task_struc > cpustat->nice = cputime64_add(cpustat->nice, tmp); > else > cpustat->user = cputime64_add(cpustat->user, tmp); > + > + cpuacct_update_stats(p, CPUACCT_STAT_UTIME, cputime); > /* Account for user time used */ > acct_update_integrals(p); > } > @@ -4440,6 +4454,8 @@ void account_system_time(struct task_str > else > cpustat->system = cputime64_add(cpustat->system, tmp); > > + cpuacct_update_stats(p, CPUACCT_STAT_STIME, cputime); > + > /* Account for system time used */ > acct_update_integrals(p); > } > @@ -9723,6 +9739,7 @@ struct cpuacct { > struct cgroup_subsys_state css; > /* cpuusage holds pointer to a u64-type object on every cpu */ > u64 *cpuusage; > + struct percpu_counter cpustat[CPUACCT_STAT_NSTATS]; > struct cpuacct *parent; > }; > > @@ -9747,20 +9764,33 @@ static struct cgroup_subsys_state *cpuac > struct cgroup_subsys *ss, struct cgroup *cgrp) > { > struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL); > + int i; > > if (!ca) > - return ERR_PTR(-ENOMEM); > + goto out; > > ca->cpuusage = alloc_percpu(u64); > - if (!ca->cpuusage) { > - kfree(ca); > - return ERR_PTR(-ENOMEM); > - } > + if (!ca->cpuusage) > + goto out_free_ca; > + > + for (i = 0; i < CPUACCT_STAT_NSTATS; i++) > + if (percpu_counter_init(&ca->cpustat[i], 0)) > + goto out_free_counters; > > if (cgrp->parent) > ca->parent = cgroup_ca(cgrp->parent); > > return &ca->css; > + > +out_free_counters: > + i--; > + while (i-- >= 0) > + percpu_counter_destroy(&ca->cpustat[i]); > + free_percpu(ca->cpuusage); > +out_free_ca: > + kfree(ca); > +out: > + return ERR_PTR(-ENOMEM); > } > > /* destroy an existing cpu accounting group */ > @@ -9768,7 +9798,10 @@ static void > cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) > { > struct cpuacct *ca = cgroup_ca(cgrp); > + int i; > > + for (i = 0; i < CPUACCT_STAT_NSTATS; i++) > + percpu_counter_destroy(&ca->cpustat[i]); > free_percpu(ca->cpuusage); > kfree(ca); > } > @@ -9855,6 +9888,25 @@ static int cpuacct_percpu_seq_read(struc > return 0; > } > > +static const char *cpuacct_stat_desc[] = { > + [CPUACCT_STAT_UTIME] = "utime", > + [CPUACCT_STAT_STIME] = "stime", > +}; > + > +static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft, > + struct cgroup_map_cb *cb) > +{ > + struct cpuacct *ca = cgroup_ca(cgrp); > + int i; > + > + for (i = 0; i < CPUACCT_STAT_NSTATS; i++) { > + s64 val = percpu_counter_read(&ca->cpustat[i]); > + val = cputime_to_clock_t(val); > + cb->fill(cb, cpuacct_stat_desc[i], val); > + } > + return 0; > +} > + > static struct cftype files[] = { > { > .name = "usage", > @@ -9865,7 +9917,10 @@ static struct cftype files[] = { > .name = "usage_percpu", > .read_seq_string = cpuacct_percpu_seq_read, > }, > - > + { > + .name = "stat", > + .read_map = cpuacct_stats_show, > + }, > }; > > static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp) > @@ -9895,6 +9950,25 @@ static void cpuacct_charge(struct task_s > } > } > > +/* > + * Account the system/user time to the task's accounting group. > + */ > +static void cpuacct_update_stats(struct task_struct *tsk, > + enum cpuacct_stat_index idx, cputime_t val) > +{ > + struct cpuacct *ca; > + > + if (unlikely(!cpuacct_subsys.active)) > + return; > + > + ca = task_ca(tsk); > + > + do { > + percpu_counter_add(&ca->cpustat[idx], val); > + ca = ca->parent; > + } while (ca); > +} > + IIUC, to make sure accessing "ca" to be safe, we need some condition. (task_lock() or some other..... Could you add "why this is safe ?" as comment ? -Kame > struct cgroup_subsys cpuacct_subsys = { > .name = "cpuacct", > .create = cpuacct_create, > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
