From: Peter Zijlstra <peterz@infradead.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
Juri Lelli <juri.lelli@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC PATCH 0/7] sched: Streamline select_task_rq() & select_task_rq_fair()
Date: Mon, 6 Jan 2020 09:10:20 +0100 [thread overview]
Message-ID: <20200106081020.GL2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191211164401.5013-1-valentin.schneider@arm.com>
On Wed, Dec 11, 2019 at 04:43:54PM +0000, Valentin Schneider wrote:
> Discussion points
> =================
>
> The use of SD_LOAD_BALANCE forced me to do a few ugly things.
>
> Patch 5 is only required because the domain walk in select_task_rq_fair()
> is ceiled by the presence of SD_LOAD_BALANCE. Thing is (I also ramble about
> this in the changelog of patch 7) AFAIK this flag is set unconditionally in
> sd_init() and the only way to clear it is via the sched_domain sysctl,
> which is a SCHED_DEBUG interface. I haven't found anything with cpusets
> that would clear it; AFAICT cpusets can end up attaching the NULL domain to
> some CPUs (with sched_load_balance=0) but that's as far as this goes:
I can't find it in a hurry, but cpusets should really be able to build
stuff without LOAD_BALANCe on, otherwise it is broken.
/me digs a little into the code and finds that. no, you're right. What
cpusets does is create non-overlapping domain trees for each parition.
Which avoids the need to clear that flag.
Hmmm.. if we double check all that, I don't suppose there is anything
against simply removing that flag. Less is more etc..
prev parent reply other threads:[~2020-01-06 8:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 16:43 [RFC PATCH 0/7] sched: Streamline select_task_rq() & select_task_rq_fair() Valentin Schneider
2019-12-11 16:43 ` [RFC PATCH 1/7] sched: Add WF_TTWU, WF_EXEC wakeup flags Valentin Schneider
2019-12-11 16:43 ` [RFC PATCH 2/7] sched: Kill select_task_rq()'s sd_flag parameter Valentin Schneider
2019-12-11 16:43 ` [RFC PATCH 3/7] sched/fair: find_idlest_group(): Remove unused " Valentin Schneider
2019-12-11 16:43 ` [RFC PATCH 4/7] sched/fair: Dissociate wakeup decisions from SD flag value Valentin Schneider
2019-12-11 16:53 ` Valentin Schneider
2019-12-11 16:43 ` [RFC PATCH 5/7] sched/topology: Make {lowest/highest}_flag_domain() work with > 1 flags Valentin Schneider
2019-12-11 16:44 ` [RFC PATCH 6/7] sched/fair: Split select_task_rq_fair want_affine logic Valentin Schneider
2019-12-11 16:44 ` [RFC PATCH 7/7] sched/topology: Define and use shortcut pointers for wakeup sd_flag scan Valentin Schneider
2020-01-06 8:10 ` Peter Zijlstra [this message]
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