From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <yuyang.du@intel.com>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org,
bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
lizefan@huawei.com, umgwanakikbuti@gmail.com
Subject: Re: [PATCH v3 6/6] sched/fair: Move (inactive) option from code to config
Date: Thu, 28 Apr 2016 11:37:33 +0200 [thread overview]
Message-ID: <20160428093733.GX3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1459829551-21625-7-git-send-email-yuyang.du@intel.com>
On Tue, Apr 05, 2016 at 12:12:31PM +0800, Yuyang Du wrote:
> The option of increased load resolution (fixed point arithmetic range) is
> unconditionally deactivated with #if 0. But since it may still be used
> somewhere (e.g., in Google), we want to keep this option.
>
> Regardless, there should be a way to express this option. Considering the
> current circumstances, the reconciliation is we define a config
> CONFIG_CFS_INCREASE_LOAD_RANGE and it depends on FAIR_GROUP_SCHED and
> 64BIT and BROKEN.
>
> Suggested-by: Ingo Molnar <mingo@kernel.org>
So I'm very tempted to simply, unconditionally, reinstate this larger
range for everything CONFIG_64BIT && CONFIG_FAIR_GROUP_SCHED.
There was but the single claim on increased power usage, nobody could
reproduce / analyze and Google has been running with this for years now.
Furthermore, it seems to be leading to the obvious problems on bigger
machines where we basically run out of precision by the sheer number of
cpus (nr_cpus ~ SCHED_LOAD_SCALE and stuff comes apart quickly).
next prev parent reply other threads:[~2016-04-28 9:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 4:12 [PATCH v3 0/6] sched/fair: Clean up sched metric definitions Yuyang Du
2016-04-05 4:12 ` [PATCH v3 1/6] sched/fair: Generalize the load/util averages resolution definition Yuyang Du
2016-05-05 9:39 ` [tip:sched/core] " tip-bot for Yuyang Du
2016-04-05 4:12 ` [PATCH v3 2/6] sched/fair: Remove SCHED_LOAD_SHIFT and SCHED_LOAD_SCALE Yuyang Du
2016-05-05 9:40 ` [tip:sched/core] sched/fair: Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT and remove SCHED_LOAD_SCALE tip-bot for Yuyang Du
2016-04-05 4:12 ` [PATCH v3 3/6] sched/fair: Add introduction to the sched load avg metrics Yuyang Du
2016-05-05 9:41 ` [tip:sched/core] sched/fair: Add detailed description " tip-bot for Yuyang Du
2016-04-05 4:12 ` [PATCH v3 4/6] sched/fair: Remove scale_load_down() for load_avg Yuyang Du
2016-04-28 10:25 ` Peter Zijlstra
2016-04-28 3:01 ` Yuyang Du
2016-04-28 19:29 ` Yuyang Du
2016-04-05 4:12 ` [PATCH v3 5/6] sched/fair: Rename scale_load() and scale_load_down() Yuyang Du
2016-04-28 9:19 ` Peter Zijlstra
2016-04-28 11:18 ` Vincent Guittot
2016-04-28 20:30 ` Yuyang Du
2016-04-05 4:12 ` [PATCH v3 6/6] sched/fair: Move (inactive) option from code to config Yuyang Du
2016-04-28 9:37 ` Peter Zijlstra [this message]
2016-04-28 9:45 ` Ingo Molnar
2016-04-28 20:34 ` Yuyang Du
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