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=-2.7 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, URIBL_BLOCKED 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 F3B51C433E6 for ; Thu, 28 Jan 2021 14:31:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6938764DDB for ; Thu, 28 Jan 2021 14:31:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6938764DDB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EAB8D6B0078; Thu, 28 Jan 2021 09:31:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E5D7D6B007B; Thu, 28 Jan 2021 09:31:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D71E46B007D; Thu, 28 Jan 2021 09:31:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0202.hostedemail.com [216.40.44.202]) by kanga.kvack.org (Postfix) with ESMTP id B98056B0078 for ; Thu, 28 Jan 2021 09:31:37 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 734278249980 for ; Thu, 28 Jan 2021 14:31:37 +0000 (UTC) X-FDA: 77755422234.21.trade69_4f0b397275a0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id 2187B180442E5 for ; Thu, 28 Jan 2021 14:31:36 +0000 (UTC) X-HE-Tag: trade69_4f0b397275a0 X-Filterd-Recvd-Size: 4026 Received: from mail-lf1-f50.google.com (mail-lf1-f50.google.com [209.85.167.50]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 14:31:35 +0000 (UTC) Received: by mail-lf1-f50.google.com with SMTP id q8so7827013lfm.10 for ; Thu, 28 Jan 2021 06:31:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=U88i4bYD+2ZCQHQ1c+KWUX/qpCWETVcRAa2ygsI9PbM=; b=ktNcZy4FM+idXljNJ/QPUrrkMM+6sqAWkC4IUBuLdTFl4+6svYUZZqbz2cMaXlmXHz EfIxAjWA0aeS2bt2ise3utHgxAX7tHZ+/vUAHvdzppwUqPznb1bHVaQXDsgbWdf0S12W SFqlze+1S+3/F75pfGXibVkKoyz6djNhboBdWHWMO5LIJ/Nhtsz3tktse2zk/yuB+S+m BBGzVIbwo2C06laQw9/fDXHWo42366CQkv7YvtMZBa4qMILH7e70kws6X64g1SvTGhsu 4erWwERwvujKZOhaFwkq7sSZp83lwqVno2UHlcRtXwobChLTmU+MuBIzyaC1D4Ia6Ry/ fHIQ== 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=U88i4bYD+2ZCQHQ1c+KWUX/qpCWETVcRAa2ygsI9PbM=; b=AmTyEeL1PfJBCurfxIvGjYCH0JyubFAt3DdKGDcYJI/RW85LdMc926MtT0LsgrYzFU Eq5b4puTozrkaUzdGi8+qLXDfK/7Yh/hLSh3x08d+U1hxtOheWue9w5chRa3L4vPT7bQ 2vQFLqyZynWPvLW/fwDIhZT9MON4vav8l1hHKvzAtQohAl0eFdGOwgYYuy3AIy8d+GmX 3/b+zc0gRbJ5c6IqdBICRBjAeDcbqrfmbPnkHJBuvxcnWd6lv3BXBw3/GkaVdJCaO9Gp 0git+09fBJUNJ2LarxVkXSJOkc4z8TaTwuByMT6r4e6PRxc30enqu1JBYgQufdqGu7w+ OdTQ== X-Gm-Message-State: AOAM533cs5aytmYPYvSauFJylnQ//r7LOQCdUrXKXMdP2yB0+zmLVAHH 3aTYnF1PXh7ETVk9uGwgOTd4u1RGT6unw7dYT1I= X-Google-Smtp-Source: ABdhPJw/FG33c8uxAD7OMrDy2u2glk5wjaE+qBImvOA3IzWPa2rTRQ7MGY4krYnNoa5K0MfFL7Vl+rnFlIMA9O7XVLw= X-Received: by 2002:a19:3fcc:: with SMTP id m195mr7574839lfa.459.1611844294381; Thu, 28 Jan 2021 06:31:34 -0800 (PST) MIME-Version: 1.0 References: <20210128130411.6125-1-vvghjk1234@gmail.com> <20210128132508.GE3592@techsingularity.net> <095faeec-ecb1-77c8-6118-267d28710508@suse.cz> <20210128142257.GG3592@techsingularity.net> In-Reply-To: <20210128142257.GG3592@techsingularity.net> From: Wonhyuk Yang Date: Thu, 28 Jan 2021 23:31:23 +0900 Message-ID: Subject: Re: [PATCH v2] mm/compactoin: Fix misbehaviors of fast_find_migrateblock() To: Mel Gorman Cc: Vlastimil Babka , Andrew Morton , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" 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 Thu, Jan 28, 2021 at 11:23 PM Mel Gorman wrote: > > On Thu, Jan 28, 2021 at 03:01:27PM +0100, Vlastimil Babka wrote: > > On 1/28/21 2:50 PM, Wonhyuk Yang wrote: > > > On Thu, Jan 28, 2021 at 10:25 PM Mel Gorman wrote: > > >> > > >> As nr_scanned is post-incremented, this will still consider if the page > > >> should be used when the limit is reached. ++nr_scanned? > > > > > > Hi, > > > > > > Let's consider that limit is 4, nr_scanned is 0 and loop until reach the limit. > > > 1) pre-increment: it will search three times.(0,1,2) > > > 2) post-increment: it will search four times. (0,1,2,3) > > > > > > So you mean that searching three times is correct? > > > > 1) will match the outer loop's "nr_scanned < limit;" condition. It doesn't > > matter that much in practice, but for consistency sake, it should be 1) > > Ok, while I find it a little strange to enter the loop and then break > immediately due to the limit, it's a marginal difference and in general, > the patch makes sense. > Then, should I change post-increment to pre-increment? If so, should I send a new version? It seems like it's too tiny change...