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Date: Tue, 12 Oct 2010 23:44:29 -0700 From: Paul Turner <pjt@...gle.com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Cc: bharata@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org, Dhaval Giani <dhaval.giani@...il.com>, Balbir Singh <balbir@...ux.vnet.ibm.com>, Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>, Srivatsa Vaddagiri <vatsa@...ibm.com>, Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>, Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Pavel Emelyanov <xemul@...nvz.org>, Herbert Poetzl <herbert@...hfloor.at>, Avi Kivity <avi@...hat.com>, Chris Friesen <cfriesen@...tel.com>, Paul Menage <menage@...gle.com>, Mike Waychison <mikew@...gle.com>, Nikhil Rao <ncrao@...gle.com> Subject: Re: [PATCH v3 3/7] sched: throttle cfs_rq entities which exceed their local quota On Tue, Oct 12, 2010 at 11:34 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote: > On Tue, 12 Oct 2010 13:22:02 +0530 > Bharata B Rao <bharata@...ux.vnet.ibm.com> wrote: > >> sched: throttle cfs_rq entities which exceed their local quota >> >> From: Paul Turner <pjt@...gle.com> >> >> In account_cfs_rq_quota() (via update_curr()) we track consumption versus a >> cfs_rq's local quota and whether there is global quota available to continue >> enabling it in the event we run out. >> >> This patch adds the required support for the latter case, throttling entities >> until quota is available to run. Throttling dequeues the entity in question >> and sends a reschedule to the owning cpu so that it can be evicted. >> >> The following restrictions apply to a throttled cfs_rq: >> - It is dequeued from sched_entity hierarchy and restricted from being >> re-enqueued. This means that new/waking children of this entity will be >> queued up to it, but not past it. >> - It does not contribute to weight calculations in tg_shares_up >> - In the case that the cfs_rq of the cpu we are trying to pull from is throttled >> it is is ignored by the loadbalancer in __load_balance_fair() and >> move_one_task_fair(). >> >> Signed-off-by: Paul Turner <pjt@...gle.com> >> Signed-off-by: Nikhil Rao <ncrao@...gle.com> >> Signed-off-by: Bharata B Rao <bharata@...ux.vnet.ibm.com> >> --- >> kernel/sched.c | 12 ++++++++ >> kernel/sched_fair.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++---- >> 2 files changed, 76 insertions(+), 6 deletions(-) >> >> --- a/kernel/sched.c >> +++ b/kernel/sched.c >> @@ -387,6 +387,7 @@ struct cfs_rq { >> #endif >> #ifdef CONFIG_CFS_BANDWIDTH >> u64 quota_assigned, quota_used; >> + int throttled; >> #endif >> #endif >> }; >> @@ -1668,6 +1669,8 @@ static void update_group_shares_cpu(stru >> } >> } >> >> +static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq); >> + > > I just curious that static-inline forward declaration is inlined ? > Hm. This function is tiny, I should just move it up, thanks. >> /* >> * Re-compute the task group their per cpu shares over the given domain. >> * This needs to be done in a bottom-up fashion because the rq weight of a >> @@ -1688,7 +1691,14 @@ static int tg_shares_up(struct task_grou >> usd_rq_weight = per_cpu_ptr(update_shares_data, smp_processor_id()); >> >> for_each_cpu(i, sched_domain_span(sd)) { >> - weight = tg->cfs_rq[i]->load.weight; >> + /* >> + * bandwidth throttled entities cannot contribute to load >> + * balance >> + */ >> + if (!cfs_rq_throttled(tg->cfs_rq[i])) >> + weight = tg->cfs_rq[i]->load.weight; >> + else >> + weight = 0; > > cpu.share and bandwidth control can't be used simultaneously or... > is this fair ? I'm not familiar with scheduler but this allows boost this tg. > Could you add a brief documentaion of a spec/feature. in the next post ? > Bandwidth control is orthogonal to shares, shares continue controls distribution of bandwidth when within quota. Bandwidth control only has 'perceivable' effect when you exceed your reservation within a quota period. What the above is doing is removing any throttled entities from the load-balancer's weight calculations (based on contribution from throttled entities) since these entities are already dequeued and cannot be balanced. Or have I misunderstood your question? > Thanks, > -Kame > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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