Messages in this thread | | | From | Nikhil Rao <> | Date | Wed, 13 Oct 2010 06:46:18 -0700 | Subject | Re: [PATCH v3 2/7] sched: accumulate per-cfs_rq cpu usage |
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On Wed, Oct 13, 2010 at 6:30 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > * Bharata B Rao <bharata@linux.vnet.ibm.com> [2010-10-12 13:21:09]: > >> sched: accumulate per-cfs_rq cpu usage >> >> From: Paul Turner <pjt@google.com> >> >> Introduce account_cfs_rq_quota() to account bandwidth usage on the cfs_rq >> level versus task_groups for which bandwidth has been assigned. This is >> tracked by whether the local cfs_rq->quota_assigned is finite or infinite >> (RUNTIME_INF). >> >> For cfs_rq's that belong to a bandwidth constrained task_group we introduce >> tg_request_cfs_quota() which attempts to allocate quota from the global pool >> for use locally. Updates involving the global pool are currently protected >> under cfs_bandwidth->lock, local pools are protected by rq->lock. >> >> This patch only attempts to assign and track quota, no action is taken in the >> case that cfs_rq->quota_used exceeds cfs_rq->quota_assigned. >> >> Signed-off-by: Paul Turner <pjt@google.com> >> Signed-off-by: Nikhil Rao <ncrao@google.com> >> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> >> --- >> include/linux/sched.h | 4 ++++ >> kernel/sched.c | 13 +++++++++++++ >> kernel/sched_fair.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ >> kernel/sysctl.c | 10 ++++++++++ >> 4 files changed, 77 insertions(+) >> >> --- a/include/linux/sched.h >> +++ b/include/linux/sched.h >> @@ -1898,6 +1898,10 @@ int sched_rt_handler(struct ctl_table *t >> void __user *buffer, size_t *lenp, >> loff_t *ppos); >> >> +#ifdef CONFIG_CFS_BANDWIDTH >> +extern unsigned int sysctl_sched_cfs_bandwidth_slice; >> +#endif >> + >> extern unsigned int sysctl_sched_compat_yield; >> >> #ifdef CONFIG_RT_MUTEXES >> --- a/kernel/sched.c >> +++ b/kernel/sched.c >> @@ -1929,6 +1929,19 @@ static const struct sched_class rt_sched >> * default: 0.5s >> */ >> static u64 sched_cfs_bandwidth_period = 500000000ULL; >> + >> +/* >> + * default slice of quota to allocate from global tg to local cfs_rq pool on >> + * each refresh >> + * default: 10ms >> + */ >> +unsigned int sysctl_sched_cfs_bandwidth_slice = 10000UL; >> + >> +static inline u64 sched_cfs_bandwidth_slice(void) >> +{ >> + return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; >> +} >> + >> #endif >> >> #define sched_class_highest (&rt_sched_class) >> --- a/kernel/sched_fair.c >> +++ b/kernel/sched_fair.c >> @@ -267,6 +267,16 @@ find_matching_se(struct sched_entity **s >> >> #endif /* CONFIG_FAIR_GROUP_SCHED */ >> >> +#ifdef CONFIG_CFS_BANDWIDTH >> +static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) >> +{ >> + return &tg->cfs_bandwidth; >> +} >> + >> +static void account_cfs_rq_quota(struct cfs_rq *cfs_rq, >> + unsigned long delta_exec); >> +#endif >> + >> >> /************************************************************** >> * Scheduling class tree data structure manipulation methods: >> @@ -547,6 +557,9 @@ static void update_curr(struct cfs_rq *c >> cpuacct_charge(curtask, delta_exec); >> account_group_exec_runtime(curtask, delta_exec); >> } >> +#ifdef CONFIG_CFS_BANDWIDTH >> + account_cfs_rq_quota(cfs_rq, delta_exec); >> +#endif >> } >> >> static inline void >> @@ -1130,6 +1143,43 @@ static void yield_task_fair(struct rq *r >> } >> >> #ifdef CONFIG_CFS_BANDWIDTH >> +static u64 tg_request_cfs_quota(struct task_group *tg) >> +{ >> + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); >> + u64 delta = 0; >> + >> + if (cfs_b->runtime > 0 || cfs_b->quota == RUNTIME_INF) { > > Quick question for cfs_b->quota == RUNTIME_INF, won't cfs_b->runtime > be always > 0?
Hi Balbir,
cfs_b->runtime can be 0 if the task group exhausts its quota. cfs_b->runtime is a counter that is periodically refreshed to cfs_b->quota, and is decremented every time a cfs_rq requests a slice.
-Thanks, Nikhil
> >> + raw_spin_lock(&cfs_b->lock); >> + /* >> + * it's possible a bandwidth update has changed the global >> + * pool. >> + */ >> + if (cfs_b->quota == RUNTIME_INF) >> + delta = sched_cfs_bandwidth_slice(); >> + else { >> + delta = min(cfs_b->runtime, >> + sched_cfs_bandwidth_slice()); >> + cfs_b->runtime -= delta; >> + } >> + raw_spin_unlock(&cfs_b->lock); >> + } >> + return delta; >> +} >> + >> +static void account_cfs_rq_quota(struct cfs_rq *cfs_rq, >> + unsigned long delta_exec) >> +{ >> + if (cfs_rq->quota_assigned == RUNTIME_INF) >> + return; >> + >> + cfs_rq->quota_used += delta_exec; >> + >> + if (cfs_rq->quota_used < cfs_rq->quota_assigned) >> + return; >> + >> + cfs_rq->quota_assigned += tg_request_cfs_quota(cfs_rq->tg); >> +} >> + >> static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) >> { >> return 1; >> --- a/kernel/sysctl.c >> +++ b/kernel/sysctl.c >> @@ -384,6 +384,16 @@ static struct ctl_table kern_table[] = { >> .mode = 0644, >> .proc_handler = proc_dointvec, >> }, >> +#ifdef CONFIG_CFS_BANDWIDTH >> + { >> + .procname = "sched_cfs_bandwidth_slice_us", >> + .data = &sysctl_sched_cfs_bandwidth_slice, >> + .maxlen = sizeof(unsigned int), >> + .mode = 0644, >> + .proc_handler = proc_dointvec_minmax, >> + .extra1 = &one, >> + }, >> +#endif >> #ifdef CONFIG_PROVE_LOCKING >> { >> .procname = "prove_locking", > > -- > Three Cheers, > Balbir > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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