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From: Qais Yousef <qais.yousef@arm.com>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Quentin Perret <qperret@google.com>,
	Pavan Kondeti <pkondeti@codeaurora.org>,
	Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH 0/8] sched/fair: misfit task load-balance tweaks
Date: Wed, 3 Feb 2021 15:14:00 +0000	[thread overview]
Message-ID: <20210203151400.ommltjjyuok4yj5e@e107158-lin> (raw)
In-Reply-To: <20210128183141.28097-1-valentin.schneider@arm.com>

On 01/28/21 18:31, Valentin Schneider wrote:
> Hi folks,
> 
> Here is this year's series of misfit changes. On the menu:
> 
> o Patch 1 is an independent active balance cleanup
> o Patch 2 adds some more sched_asym_cpucapacity static branches
> o Patch 3 introduces yet another margin for capacity to capacity
>   comparisons
> o Patches 4-6 build on top of patch 3 and change capacity comparisons
>   throughout misfit load balancing  
> o Patches 7-8 fix some extra misfit issues I've been seeing on "real"
>   workloads.
> 
> IMO the somewhat controversial bit is patch 3, because it attempts to solve
> margin issues by... Adding another margin. This does solve issues on
> existing platforms (e.g. Pixel4), but we'll be back to square one the day
> some "clever" folks spin a platform with two different CPU capacities less than
> 5% apart.

One more margin is a cause of apprehension to me. But in this case I think it
is the appropriate thing to do now. I can't think of a scenario where this
could hurt.

Thanks

--
Qais Yousef

  parent reply	other threads:[~2021-02-03 15:17 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-28 18:31 [PATCH 0/8] sched/fair: misfit task load-balance tweaks Valentin Schneider
2021-01-28 18:31 ` [PATCH 1/8] sched/fair: Clean up active balance nr_balance_failed trickery Valentin Schneider
2021-02-03 15:14   ` Qais Yousef
2021-02-03 18:42     ` Valentin Schneider
2021-02-04 15:05       ` Qais Yousef
2021-02-05 13:51   ` Vincent Guittot
2021-02-05 14:05     ` Valentin Schneider
2021-02-05 14:34       ` Vincent Guittot
2021-01-28 18:31 ` [PATCH 2/8] sched/fair: Add more sched_asym_cpucapacity static branch checks Valentin Schneider
2021-02-03 15:14   ` Qais Yousef
2021-02-09  8:42   ` Vincent Guittot
2021-01-28 18:31 ` [PATCH 3/8] sched/fair: Tweak misfit-related capacity checks Valentin Schneider
2021-02-03 15:15   ` Qais Yousef
2021-02-03 18:42     ` Valentin Schneider
2021-02-05 14:31   ` Vincent Guittot
2021-02-05 16:59     ` Valentin Schneider
2021-02-05 17:17       ` Vincent Guittot
2021-02-05 20:07         ` Valentin Schneider
2021-02-08 15:29           ` Vincent Guittot
2021-02-08 17:49             ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 4/8] sched/fair: Use dst_cpu's capacity rather than group {min, max} capacity Valentin Schneider
2021-02-03 15:15   ` Qais Yousef
2021-01-28 18:31 ` [PATCH 5/8] sched/fair: Make check_misfit_status() only compare dynamic capacities Valentin Schneider
2021-02-03 15:15   ` Qais Yousef
2021-02-04 10:49     ` Dietmar Eggemann
2021-02-04 11:34       ` Valentin Schneider
2021-02-04 14:57         ` Dietmar Eggemann
2021-01-28 18:31 ` [PATCH 6/8] sched/fair: Filter out locally-unsolvable misfit imbalances Valentin Schneider
2021-02-03 15:16   ` Qais Yousef
2021-02-03 18:43     ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 7/8] sched/fair: Attempt misfit active balance when migration_type != migrate_misfit Valentin Schneider
2021-02-03 15:16   ` Qais Yousef
2021-02-03 18:43     ` Valentin Schneider
2021-02-04 11:44       ` Dietmar Eggemann
2021-02-04 12:22         ` Valentin Schneider
2021-02-09  8:58   ` Vincent Guittot
2021-02-09 18:19     ` Valentin Schneider
2021-01-28 18:31 ` [PATCH 8/8] sched/fair: Relax task_hot() for misfit tasks Valentin Schneider
2021-02-03 15:17   ` Qais Yousef
2021-02-08 16:21   ` Vincent Guittot
2021-02-08 18:24     ` Valentin Schneider
2021-02-09  8:56       ` Vincent Guittot
2021-02-03 15:14 ` Qais Yousef [this message]
2021-02-03 18:43   ` [PATCH 0/8] sched/fair: misfit task load-balance tweaks Valentin Schneider
2021-02-04 12:03     ` Dietmar Eggemann
2021-02-04 12:36       ` Valentin Schneider

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