From: Yuyang Du <yuyang.du@intel.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Benjamin Segall <bsegall@google.com>,
Paul Turner <pjt@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Matt Fleming <matt@codeblueprint.co.uk>,
Mike Galbraith <umgwanakikbuti@gmail.com>
Subject: Re: [PATCH v1 00/10] Optimize sched avgs computation and implement flat util hierarchy
Date: Mon, 29 Aug 2016 09:37:31 +0800 [thread overview]
Message-ID: <20160829013731.GH3273@intel.com> (raw)
In-Reply-To: <474c486c-84b3-14b0-6861-336a129f7ed8@arm.com>
On Tue, Aug 23, 2016 at 04:39:51PM +0100, Dietmar Eggemann wrote:
> On 23/08/16 15:45, Vincent Guittot wrote:
> > On 23 August 2016 at 16:13, Peter Zijlstra <peterz@infradead.org> wrote:
> >> On Tue, Aug 23, 2016 at 03:28:19PM +0200, Vincent Guittot wrote:
> >>> I still wonder if using a flat util hierarchy is the right solution to
> >>> solve this problem with utilization and task group. I have noticed
> >>> exact same issues with load that generates weird task placement
> >>> decision and i think that we should probably try to solve both wrong
> >>> behavior with same mechanism. but this is not possible with flat
> >>> hierarchy for load
> >>>
> >>> Let me take an example.
> >>> TA is a always running task on CPU1 in group /root/level1/
> >>> TB wakes up on CPU0 and moves TA into group /root/level2/
> >>> Even if TA stays on CPU1, runnable_load_avg of CPU1 root cfs rq will become 0.
> >>
> >> Because while we migrate the load_avg on /root/level2, we do not
> >> propagate the load_avg up the hierarchy?
> >
> > yes. At now, the load of a cfs_rq and the load of its sched_entity
> > that represents it at parent level are disconnected
>
> I guess you say 'disconnected' because cfs_rq and se (w/ cfs_rq eq.
> se->my_q) are now independent pelt signals where as before the rewrite
> they were 'connected' for load via __update_tg_runnable_avg(),
> __update_group_entity_contrib() in __update_entity_load_avg_contrib()
> and for utilization via 'se->avg.utilization_avg_contrib =
> group_cfs_rq(se)->utilization_load_avg' in
> __update_entity_utilization_avg_contrib().
I don't understand what exactly "disconnected" means, but with respect to
group_entity's load_avg, nothing is changed essentially:
group_entity_load_avg = my_cfs_rq_load_avg / tg_load_avg * tg_shares
next prev parent reply other threads:[~2016-08-29 9:32 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-10 0:14 [PATCH v1 00/10] Optimize sched avgs computation and implement flat util hierarchy Yuyang Du
2016-08-10 0:14 ` [PATCH v1 01/10] sched/fair: Chance LOAD_AVG_MAX_N from 345 to 347 Yuyang Du
2016-08-24 16:01 ` Vincent Guittot
2016-08-29 0:07 ` Yuyang Du
2016-08-10 0:14 ` [PATCH v1 02/10] documentation: Add scheduler/sched-avg.txt Yuyang Du
2016-08-22 16:48 ` Randy Dunlap
2016-08-10 0:14 ` [PATCH v1 03/10] sched/fair: Add static to remove_entity_load_avg() Yuyang Du
2016-08-10 0:14 ` [PATCH v1 04/10] sched/fair: Rename variable names for sched averages Yuyang Du
2016-08-10 0:14 ` [PATCH v1 05/10] sched/fair: Add __always_inline compiler attribute to __accumulate_sum() Yuyang Du
2016-08-10 0:14 ` [PATCH v1 06/10] sched/fair: Optimize __update_sched_avg() Yuyang Du
2016-08-10 0:14 ` [PATCH v1 07/10] sched/fair: Remove useless 64-bit to 32-bit variable conversion Yuyang Du
2016-08-25 7:11 ` Vincent Guittot
2016-08-29 1:00 ` Yuyang Du
2016-08-10 0:14 ` [PATCH v1 08/10] sched/fair: Remove scale_load_down() for load_avg Yuyang Du
2016-08-10 0:14 ` [PATCH v1 09/10] sched/fair: Rename scale_load() and scale_load_down() Yuyang Du
2016-08-10 0:14 ` [PATCH v1 10/10] sched/fair: Implement flat hierarchical structure for util_avg Yuyang Du
2016-08-10 0:23 ` [PATCH v1 00/10] Optimize sched avgs computation and implement flat util hierarchy Yuyang Du
2016-08-22 23:26 ` Yuyang Du
2016-08-23 13:28 ` Vincent Guittot
2016-08-23 14:13 ` Peter Zijlstra
2016-08-23 14:45 ` Vincent Guittot
2016-08-23 15:39 ` Dietmar Eggemann
2016-08-29 1:37 ` Yuyang Du [this message]
2016-09-01 18:32 ` Dietmar Eggemann
2016-08-24 8:54 ` Morten Rasmussen
2016-08-24 9:48 ` Vincent Guittot
2016-08-29 19:00 ` Yuyang Du
2016-09-01 14:22 ` Morten Rasmussen
2016-08-23 19:09 ` Yuyang Du
2016-08-23 19:01 ` Yuyang Du
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