From: Peter Zijlstra <peterz@infradead.org>
To: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Qing Wang <wangqing7171@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Chen Yu <yu.c.chen@intel.com>,
Davi Chaves Azevedo <davichazbh@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] sched/fair: Replace random newidle_balance with Bresenham accumulator
Date: Fri, 30 Oct 2026 10:56:30 +0100 [thread overview]
Message-ID: <20261030095630.GJ2668200@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <a0dc959a-a05f-4725-86c9-1b7299d9b2a3@amd.com>
On Fri, Oct 30, 2026 at 03:16:13PM +0530, K Prateek Nayak wrote:
> Hello Qing,
>
> On 10/30/2026 2:49 PM, Qing Wang wrote:
> > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> > index 919d0fb00bd9..79c477b47510 100644
> > --- a/kernel/sched/topology.c
> > +++ b/kernel/sched/topology.c
> > @@ -2002,6 +2002,7 @@ sd_init(struct sched_domain_topology_level *tl,
> > .newidle_call = 512,
> > .newidle_success = 256,
> > .newidle_ratio = 512,
> > + .newidle_window_pos = 0,
>
> nit.
>
> I think this value should start in a way that allows newidle balance to run at
> first attempt and then stabilize. Maybe '512; is a good number if not higher?
Funnily enough, treating this as an independent variable and using a
random number works and 'fixes' the slope change problems.
next prev parent reply other threads:[~2026-10-30 9:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-30 9:19 Qing Wang
2026-10-30 9:46 ` K Prateek Nayak
2026-10-30 9:56 ` Peter Zijlstra [this message]
2026-10-30 10:22 ` Qing Wang
2026-10-30 10:39 ` Peter Zijlstra
2026-10-30 10:09 ` Qing Wang
2026-10-30 14:47 ` Kayra Cizmeci
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