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 X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99D3FC433EF for ; Wed, 8 Sep 2021 03:36:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2C36160E94 for ; Wed, 8 Sep 2021 03:36:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2C36160E94 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 71C55940007; Tue, 7 Sep 2021 23:36:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6CC3C900002; Tue, 7 Sep 2021 23:36:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 59409940007; Tue, 7 Sep 2021 23:36:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0002.hostedemail.com [216.40.44.2]) by kanga.kvack.org (Postfix) with ESMTP id 4A273900002 for ; Tue, 7 Sep 2021 23:36:02 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id EBCE92BC00 for ; Wed, 8 Sep 2021 03:36:01 +0000 (UTC) X-FDA: 78562992522.30.B009B57 Received: from mail-qk1-f180.google.com (mail-qk1-f180.google.com [209.85.222.180]) by imf16.hostedemail.com (Postfix) with ESMTP id B4329F00008E for ; Wed, 8 Sep 2021 03:36:01 +0000 (UTC) Received: by mail-qk1-f180.google.com with SMTP id t4so895500qkb.9 for ; Tue, 07 Sep 2021 20:36:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=va3qLF49mXwo2qEKOYCT81K5dNv0miga50Xk8uaUMHc=; b=KdFL2XFD5/y5UwVa42KQwzyaksZ6R0j6vfMdoPNDGiqtscT87XuhFWe7Bw2HcANZPJ Kj4h3YGm+qvilaHkb4WiTwOKk1mYH32xrMTe3PLgRqupy3xMKS8uCA22um4n+ZTZtxx6 7Bv90uxICb/SeAs/zhLfY4H5x77SD2eNPaqlSCxGGXzmeqbZ8uQsgDpXanJX2LOhpNmO PiiFYAjYlZUfd6hcOM1BJJ7e5l2+6K3NDcj3WVpN8mJNIyGoiQ1SWGtB6QxcbZVaM1if rSgLKVDwk4kK94LG3C+BHpFF4Hz+WoppdBuq7neV82VuzPQQQWG/qutHVAXhPlXQbiOk VxwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=va3qLF49mXwo2qEKOYCT81K5dNv0miga50Xk8uaUMHc=; b=NnKdn1TiEc/ZscR9OV/MUwI0imIA5GukiTsp5HQqBCk0q/IR0tpX776vMcROoffa93 jB3X1kP822+K8fZqwCUSInpLNwHPWylg7hxxYt/7/q4u+hfZlX/ojDAQJlItyUJNgpe/ q1lOXSY4jCSgAJrQLLyINeL43GIerfSSGN3mPyeion6mGDNDY9L2jxcPfDEANiUTLShE 7kvZvkz28vZ94UHEvjudG7AFF0MT3hNi+nvFTHVBEjbNBcDXYWgPY50R93gvgN22b4m0 kSQllzqAl0OQt/4rCSJz5Yeis4vUtNEI204Rpr7vqH2rnuuw6MBUl+/7gTw2vRVYGC6y kARg== X-Gm-Message-State: AOAM530glWnBqTHybh05VSFqkSIlsyqdXxOWnBfkoHWRRk7itQGXkwzc hgtDIW68McGbc7y38v4p1jOoaXQE6TXDMKkfC3g= X-Google-Smtp-Source: ABdhPJx+sTzc+/ItKGf/oZR9yrZTp57Dj5D+jR/Sbww8bLVl7HyibV2aBVpWdWiaqLxp6myTzkRHi2ezPv6RJisHaFo= X-Received: by 2002:ae9:dd43:: with SMTP id r64mr1492829qkf.225.1631072160836; Tue, 07 Sep 2021 20:36:00 -0700 (PDT) MIME-Version: 1.0 References: <1631015968-9779-1-git-send-email-huangzhaoyang@gmail.com> <79c08d1d-eef5-bc15-8186-7e3367b4ebe7@suse.cz> In-Reply-To: From: Zhaoyang Huang Date: Wed, 8 Sep 2021 11:35:40 +0800 Message-ID: Subject: Re: [PATCH] mm : bail out from psi memstall after submit_bio in swap_readpage To: Johannes Weiner Cc: Vlastimil Babka , Andrew Morton , Minchan Kim , Zhaoyang Huang , "open list:MEMORY MANAGEMENT" , LKML Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=KdFL2XFD; spf=pass (imf16.hostedemail.com: domain of huangzhaoyang@gmail.com designates 209.85.222.180 as permitted sender) smtp.mailfrom=huangzhaoyang@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: bc5mctgmnc1tcn48zsanc1r8ye3ppuyu X-Rspamd-Queue-Id: B4329F00008E X-Rspamd-Server: rspam04 X-HE-Tag: 1631072161-953243 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 Tue, Sep 7, 2021 at 9:24 PM Johannes Weiner wrote: > > On Tue, Sep 07, 2021 at 08:15:30PM +0800, Zhaoyang Huang wrote: > > On Tue, Sep 7, 2021 at 8:03 PM Vlastimil Babka wrote: > > > > > > On 9/7/21 13:59, Huangzhaoyang wrote: > > > > From: Zhaoyang Huang > > > > > > > > It doesn't make sense to count IO time into psi memstall. Bail out after > > > > bio submitted. > > > > > > Isn't that the point if psi, to observe real stalls, which include IO? > > Yes, correct. > > > IO stalls could be observed within blk_io_schedule. The time cost of > > the data from block device to RAM is counted here. > > Yes, that is on purpose. The time a thread waits for swap read IO is > time in which the thread is not productive due to a lack of memory. > > For async-submitted IO, this happens in lock_page() called from > do_swap_page(). If the submitting thread directly waits after the > submit_bio(), then that should be accounted too. IMO, memstall counting should be terminated by bio submitted. blk driver fetching request and the operation on the real device shouldn't be counted in. It especially doesn't make sense in a virtualization system like XEN etc, where the blk driver is implemented via backend-frontend way that introduce memory irrelevant latency > > This patch doesn't make sense to me.