From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4096AC433EF for ; Wed, 6 Apr 2022 07:38:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8EBA06B0072; Wed, 6 Apr 2022 03:37:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 89B146B0073; Wed, 6 Apr 2022 03:37:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7623C6B0074; Wed, 6 Apr 2022 03:37:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0071.hostedemail.com [216.40.44.71]) by kanga.kvack.org (Postfix) with ESMTP id 682BA6B0072 for ; Wed, 6 Apr 2022 03:37:59 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 15682183A1EF9 for ; Wed, 6 Apr 2022 07:37:49 +0000 (UTC) X-FDA: 79325649858.29.98C1B7C Received: from mail-qv1-f41.google.com (mail-qv1-f41.google.com [209.85.219.41]) by imf18.hostedemail.com (Postfix) with ESMTP id 815421C0032 for ; Wed, 6 Apr 2022 07:37:48 +0000 (UTC) Received: by mail-qv1-f41.google.com with SMTP id b17so1624620qvf.12 for ; Wed, 06 Apr 2022 00:37:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:from:to:cc:subject:references:mime-version :content-disposition:in-reply-to; bh=d8V7VO+kcQ0mbmyy8ZkB/M+w0ELWDpQbJ0MubcHelRk=; b=jOs4/FH9L11zBGxLuILPhWUWMjiRrToNmG96XfuXI7ivphTv2rrs42hglZ/8jdDE+Y 3qV02WGwqJ1cR+/DsdkDZtCq+F+1FZGK3NahncU7Y8gDXE3ePQBNgSpws5crAynqqDyj Sj4OD7lSPJ1ELJ/Sea9K0uC+367K+Vh5e5JBJ2PSYwfwIbaG/fruHRM/kB6Kw8Le60iO yFTg8f24DypMSc8QRecDAJHYaLf1/8syeQ8IMrgDHjmycskMwLCtYA0fXqdOld6BGcCD ADLErlyGyPmqNxPT3izkjv7dT1oMHsTlDxIr5eS9XXvkS435TfloxtitO3iy/LnbDe5i 8sew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:from:to:cc:subject:references :mime-version:content-disposition:in-reply-to; bh=d8V7VO+kcQ0mbmyy8ZkB/M+w0ELWDpQbJ0MubcHelRk=; b=P5uTEXHSuCshfXNKEjJlkJsbzvBLBcgVnlOl9gPVkDqGmzFtVjEXabbKeuB0lKKxOA JCp+PY4e3TVee/W36l7xj4mKUyYOI5fAlqWKxvEm0e9/uf8svRpc76A9NOUUaeKmJAIG tDQsVLkKKA2QMf0zqQ6VGZXXSsKbPnTEaojFSA9gjA2dRDnDXleetfo0xQwIT0OfgPd4 E3t89bWPgPCZi3ELUXfBk1Vq6J+uMn8qHhTb0t881+67zBrbvB8zvhtmwJEaH1HtTh6S dcJ9srTXtKa6Ruyi8KrMVIUVeQe74B8AsNLnw3sxgycMebCzzrRzSFX1qbBBvW04Qp1f fI7Q== X-Gm-Message-State: AOAM530NfVm65P68hoyDZcpjP11HFvy++33ev8/FX3hNHpqySsm/DZZN Lw+XWlIA8hVwXG52k+3yHj0= X-Google-Smtp-Source: ABdhPJwwnFIt4rCcIgVwjIbuX+wMIjrYrcDUM+9auTHH9TsznJEiml3Zvha9G5B1PLH7bPq7N8aumw== X-Received: by 2002:a0c:ffab:0:b0:443:d915:59cc with SMTP id d11-20020a0cffab000000b00443d91559ccmr6384101qvv.44.1649230667752; Wed, 06 Apr 2022 00:37:47 -0700 (PDT) Received: from localhost ([193.203.214.57]) by smtp.gmail.com with ESMTPSA id c1-20020a05620a0ce100b0067e0cd1746fsm8806915qkj.51.2022.04.06.00.37.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 00:37:46 -0700 (PDT) Message-ID: <624d434a.1c69fb81.11e99.b2b8@mx.google.com> X-Google-Original-Message-ID: <20220406073743.GA2487892@cgel.zte@gmail.com> Date: Wed, 6 Apr 2022 07:37:43 +0000 From: CGEL To: David Hildenbrand Cc: akpm@linux-foundation.org, bsingharora@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yang Yang , Ran Xiaokai Subject: Re: [PATCH] delayacct: track delays from COW References: <20220322110444.2340748-1-yang.yang29@zte.com.cn> <9f9ddbf7-797a-58d8-2903-beacb2698329@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9f9ddbf7-797a-58d8-2903-beacb2698329@redhat.com> Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b="jOs4/FH9"; spf=pass (imf18.hostedemail.com: domain of cgel.zte@gmail.com designates 209.85.219.41 as permitted sender) smtp.mailfrom=cgel.zte@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: utng6qiwjc64utnjagwdws1cqmxy45hu X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 815421C0032 X-HE-Tag: 1649230668-337748 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, Mar 23, 2022 at 09:49:46AM +0100, David Hildenbrand wrote: > On 22.03.22 12:04, cgel.zte@gmail.com wrote: > > From: Yang Yang > > > > Delay accounting does not track the delay of COW. When tasks trigger > > much COW, it may spend a amount of time waiting for it. To get the > > impact of tasks in COW, measure the delay when it happens. This > > could help users to do tunnings, such as decide whether to use > > ksm or not. > > > > Also update tools/accounting/getdelays.c: > > > > / # ./getdelays -dl -p 231 > > print delayacct stats ON > > listen forever > > PID 231 > > > > CPU count real total virtual total delay total delay average > > 6247 1859000000 2154070021 1674255063 0.268ms > > IO count delay total delay average > > 0 0 0ms > > SWAP count delay total delay average > > 0 0 0ms > > RECLAIM count delay total delay average > > 0 0 0ms > > THRASHING count delay total delay average > > 0 0 0ms > > COMPACT count delay total delay average > > 3 72758 0ms > > COW count delay total delay average > > 3635 271567604 0ms > > You should also update Documentation/accounting/delay-accounting.rst > most probably. > > Overall LGTM and this might be of value not only for KSM but for anybody > using fork(). There will be collisions with [1], especially [2], which I > want to get in -next early after we have v5.18-rc1 (after rebasing [1] > on top of this). > > We'll have to decide if we want to also account hugetlb wp code > (hugetlb_cow), and if we want to account "unsharing" here as well under > cow (I tend to say that we want to for simplicity). For THP, we only > split and don't copy, so there isn't anything to account. > As for simplicity, what about account "PAGECOPY" instead of "COW"? "PAGECOPY" include COW and unsharing. And we may also account hugetlb wp in follow-up patches, based on this patch is sufficient reviewed. > [1] https://lore.kernel.org/r/20220315104741.63071-1-david@redhat.com > [2] https://lore.kernel.org/r/20220315104741.63071-14-david@redhat.com > > -- > Thanks, > > David / dhildenb