linux-kernel - Re: [PATCH v1 3/3] cgroup/rstat: introduce ratelimited rstat flushing

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Date: Thu, 18 Apr 2024 11:32:21 -1000
From: Tejun Heo <tj@...nel.org>
To: Yosry Ahmed <yosryahmed@...gle.com>
Cc: Jesper Dangaard Brouer <hawk@...nel.org>, hannes@...xchg.org,
	lizefan.x@...edance.com, cgroups@...r.kernel.org,
	longman@...hat.com, netdev@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, shakeel.butt@...ux.dev,
	kernel-team@...udflare.com,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	mhocko@...nel.org, Wei Xu <weixugc@...gle.com>
Subject: Re: [PATCH v1 3/3] cgroup/rstat: introduce ratelimited rstat flushing

Hello,

On Thu, Apr 18, 2024 at 02:22:58PM -0700, Yosry Ahmed wrote:
> Outside of this, I think it helps us add controller-specific
> optimizations. For example, I tried to generalize the thresholding
> code in the memory controller and put it in the rstat code, but I
> couldn't really have a single value representing the "pending stats"
> from all controllers. It's impossible to compare memory stats (mostly
> in pages or bytes) to cpu time stats for instance.
> 
> Similarly, with this proposal from Jesper (which I am not saying I am
> agreeing with :P), instead of having time-based ratelimiting in both
> the rstat code and the memcg code to support different thresholds, we
> could have the memory controller set a different threshold for itself.
> 
> So perhaps the lock breakdowns are not enough motivation, but if we
> start generalizing optimizations in some controllers, we may want to
> split the tree for flexibility.

I see. Yeah, that makes more sense to me.

Thanks.

-- 
tejun