lkml.org 
[lkml]   [2010]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v3 2/7] sched: accumulate per-cfs_rq cpu usage
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/

\
 
 \ /
  Last update: 2010-10-13 15:49    [W:0.106 / U:0.932 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site