linux-kernel - Re: [PATCH V3 1/2] sched: Reduce the default slice to avoid tasks getting an extra tick

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Message-Id: <20250222031945.67519-1-15645113830zzh@gmail.com>
Date: Sat, 22 Feb 2025 11:19:46 +0800
From: zihan zhou <15645113830zzh@...il.com>
To: qyousef@...alina.io
Cc: 15645113830zzh@...il.com,
	bsegall@...gle.com,
	dietmar.eggemann@....com,
	juri.lelli@...hat.com,
	linux-kernel@...r.kernel.org,
	mgorman@...e.de,
	mingo@...hat.com,
	peterz@...radead.org,
	rostedt@...dmis.org,
	vincent.guittot@...aro.org,
	vschneid@...hat.com
Subject: Re: [PATCH V3 1/2] sched: Reduce the default slice to avoid tasks getting an extra tick

> Yes. The minimum bar of modern hardware is higher now. And generally IMHO this
> value depends on workload. NR_CPUs can make an overloaded case harder, but it
> really wouldn't take much to saturate 8 CPUs compared to 2 CPUs. And from
> experience the larger the machine the larger the workload, so the worst case
> scenario of having to slice won't be in practice too much different. Especially
> many programmers look at NR_CPUs and spawn as many threads..
> 
> Besides with EAS we force packing, so we artificially force contention to save
> power.
> 
> Dynamically depending on rq->hr_nr_runnable looks attractive but I think this
> is a recipe for more confusion. We sort of had this with sched_period, the new
> fixed model is better IMHO.

Hi, It seems that I have been thinking less about things. I have been re
reading these emails recently. Can you give me the LPC links for these
discussions? I want to relearn this part seriously, such as why we don't
dynamically adjust the slice.

Thanks!