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Fri, 9 Jul 2021 15:18:01 +0000 Date: Fri, 9 Jul 2021 11:17:56 -0400 From: Daniel Jordan To: Hao Lee Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, tj@kernel.org Subject: Re: [Question] Do we need remote charging for cpu and cpuacct subsys? 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dkim=pass header.d=oracle.com header.s=corp-2020-01-29 header.b=xr4GBFVd; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=PSca18f2; dmarc=pass (policy=none) header.from=oracle.com; spf=none (imf15.hostedemail.com: domain of daniel.m.jordan@oracle.com has no SPF policy when checking 205.220.165.32) smtp.mailfrom=daniel.m.jordan@oracle.com X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A9723D00009F X-Stat-Signature: x3tjs4paotnpup81gy8c7nyfq9f7cueq X-HE-Tag: 1625843887-393840 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000021, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi, [only replying now b/c I was out most of this week] On Sun, Jul 04, 2021 at 12:18:22AM +0800, Hao Lee wrote: > On Sat, Jul 3, 2021 at 4:07 AM Daniel Jordan wrote: > > So naturally, I'm curious about your use case and how it may be > > different from these others. What kworkers would you like to account? > > Thanks. We use a workqueue to perform asynchronous reclaim for cgroups. > The kworker may consume lots of CPU cycles if the cgroup memory pressure > is extremely high, so we want to charge the cpu usage to the related > cgroup for which the kworker works. Otherwise, the reclaim kworker will > steal cpu time from the system level, which breaks the resource isolation. Ok, that helps. > I also have a question here. Are the back-charging and remote charging > the same thing? Basically yes. > > The only one I'm aware of > > that's like that is net rx, where the work to process packets has to > > start before their ultimate destination, and therefore cgroup, is known. > > Sorry. Is this a typo? It seems the word "known" should be "unknown"... What I'm saying is, the work to process packets starts when the cgroup is unknown.