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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ilWBpVaz7tim4BhtPmkdQdhYCNjSuFWWWOgzt2FZgCw=; b=bYQi9IrugysS3aFilKMq1wJP0+ml/cUpbgFpu56WvZNS0RWri6sxCbyToYTNbyzyiW hFBagdDo2Gyx2P5iDV4auPMtP/prFaAtA2UBq+zG5rJ6p2/hdyYDpFrDjoJfvhO4xtMF o5kpRO+g000+xma/3jDSNtIG4Cc6esNql8lliO9npgZY/K5MT/ruPkL1h51tBZeL22GT aEEv3Svw8vDog/SeQ3l7yTTWYu6gSxM/MvMTSq4nDNvYDO84ry3RsCZmRrqewZliH7c/ PlrFU/L8mibtbBhRK+FAvD/E3CosWdRB1o1ZbkybgMF02DdXSr2lhqAbMQKJ44ZMktwT 966A== X-Gm-Message-State: AOAM533FuT6OIMxMZb82qQ6kA3E9P1TbZl5MCAOE95rGA+DXgVTpll1Y Og/uKDDxYZCQy/KRMwryT35kqmL+m85jIphnqJs= X-Google-Smtp-Source: ABdhPJzi1DpXVEX8Nlxe6yE//4t+uaInxzWKxX6RTjKSF/eOF6Rn9i3s45RxwtOWlovwZfaMxqiknpjO9NESNxwuSrc= X-Received: by 2002:a05:620a:450a:: with SMTP id t10mr11607242qkp.412.1636534087567; Wed, 10 Nov 2021 00:48:07 -0800 (PST) MIME-Version: 1.0 References: <1634278612-17055-1-git-send-email-huangzhaoyang@gmail.com> In-Reply-To: From: Zhaoyang Huang Date: Wed, 10 Nov 2021 16:47:46 +0800 Message-ID: Subject: Re: [Resend PATCH] psi : calc cfs task memstall time more precisely To: Peter Zijlstra Cc: Vincent Guittot , Dietmar Eggemann , Ke Wang , xuewen.yan@unisoc.com, Johannes Weiner , Andrew Morton , Michal Hocko , Vladimir Davydov , Zhaoyang Huang , "open list:MEMORY MANAGEMENT" , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 2C329F000211 X-Stat-Signature: q5b1ub9brhhhecr994tbctfqcd93k9ky Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=p19pENSi; spf=pass (imf11.hostedemail.com: domain of huangzhaoyang@gmail.com designates 209.85.222.178 as permitted sender) smtp.mailfrom=huangzhaoyang@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1636534088-100984 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 10, 2021 at 4:36 PM Peter Zijlstra wrote: > > On Wed, Nov 10, 2021 at 09:37:00AM +0800, Zhaoyang Huang wrote: > > On Tue, Nov 9, 2021 at 10:56 PM Peter Zijlstra wrote: > > > > > > On Tue, Nov 02, 2021 at 03:47:33PM -0400, Johannes Weiner wrote: > > > > CC peterz as well for rt and timekeeping magic > > > > > > > > On Fri, Oct 15, 2021 at 02:16:52PM +0800, Huangzhaoyang wrote: > > > > > From: Zhaoyang Huang > > > > > > > > > > In an EAS enabled system, there are two scenarios discordant to current design, > > > > > > > > > > 1. workload used to be heavy uneven among cores for sake of scheduler policy. > > > > > RT task usually preempts CFS task in little core. > > > > > 2. CFS task's memstall time is counted as simple as exit - entry so far, which > > > > > ignore the preempted time by RT, DL and Irqs. > > > > > > It ignores preemption full-stop. I don't see why RT/IRQ should be > > > special cased here. > > As Johannes comments, what we are trying to solve is mainly the > > preempted time of the CFS task by RT/IRQ, NOT the RT/IRQ themselves. > > Could you please catch up the recent reply of Dietmar, which maybe > > provide more information. > > In that case NAK. Would you please explaining if there is any constraint to prevent from doing so? We do think eliminating the preempted time is reasonable and doable as it is memory irrelevant but probably related to lack of CPU etc.