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 62D3EC636CD for ; Fri, 10 Feb 2023 08:12:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CA4F56B010D; Fri, 10 Feb 2023 03:12:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C545F6B010E; Fri, 10 Feb 2023 03:12:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B42F06B010F; Fri, 10 Feb 2023 03:12:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id A545D6B010D for ; Fri, 10 Feb 2023 03:12:32 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 64B3914056A for ; Fri, 10 Feb 2023 08:12:32 +0000 (UTC) X-FDA: 80450665344.24.E28AA66 Received: from out-243.mta1.migadu.com (out-243.mta1.migadu.com [95.215.58.243]) by imf13.hostedemail.com (Postfix) with ESMTP id 42E2D20007 for ; Fri, 10 Feb 2023 08:12:29 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=xm7MF3M1; spf=pass (imf13.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.243 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676016750; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0iIN3s9vceowifsKNRpYFbtpERy3OAkbKuMLhL+6OCs=; b=eoE5PgvKLnS13erjYMc85IgJQn7q7z4s8+s74+hb7uBNf7xxalC92ntKEKjnfkQRDsDfvO sz9I+udcrkHB0V5CXDI6vGC8FwVhcpAsqS0CwTGx1iWP4taZ5To4648JCFBJgKuOvNl7dL IiZapgtIlob7TbCJQdlG2KS/hLRgzqE= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=xm7MF3M1; spf=pass (imf13.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.243 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676016750; a=rsa-sha256; cv=none; b=K7UWtB4xrxq41ExfcNYd8lzEeiZT/7O19mPILy7+YDNalrE4L8yvMolLxmEAnAH0XL7cxA +6rKofLE+H5jWFAWlXKpuYVFt4KaQSwUS//4GG/OUNPv2/Szfd9Fv/IDnsX1qE0l9ycElO bLAuhJg5ir6ihMQHWJLn4IZztn6a4W4= MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1676016747; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0iIN3s9vceowifsKNRpYFbtpERy3OAkbKuMLhL+6OCs=; b=xm7MF3M1UrxQOTkLJJxrLvzbdGX2ezmqbvS9gW3dvv2NWG2URyMWdtqyRk/zFHJsfCtjUO 2lC9s78TQMa8MDMu6eHYFstTI746vThdY0/yyHI0maG0q3FCDMlE2umsoqdagokbQQycxE a0qVc7I+P/SVKz4iniAWyfwPsPU4QJ8= Date: Fri, 10 Feb 2023 08:12:23 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Yajun Deng" Message-ID: <58d940aba3433bc6928e91c2272a8410@linux.dev> Subject: Re: [PATCH v2] mm/page_alloc: optimize find_suitable_fallback() and fallbacks array To: "Vlastimil Babka" , akpm@linux-foundation.org Cc: mgorman@techsingularity.net, david@redhat.com, rppt@linux.ibm.com, osalvador@suse.de, rppt@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ziy@nvidia.com In-Reply-To: References: <626a5f4c4996f57631a8e1877c7646e5@linux.dev> <494D9F5D-33A4-48B4-911B-9A75CFC9BC67@nvidia.com> <4C196D76-49A9-4B06-A51F-D8A13109DF3B@nvidia.com> <20230209101144.496144-1-yajun.deng@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 42E2D20007 X-Stat-Signature: zcb3ref3b6ewf4h73af11asm7owotee1 X-Rspam-User: X-HE-Tag: 1676016749-585423 X-HE-Meta: U2FsdGVkX189mmGDZngPJ3NQfeuQgnQfKdcAH+oaQKJx2c5FDcHL1deY8sTxBviXQ76j6ktWFPvN587yWqp27p7ea8sLl7sWuqIK7xt2u5ysuVdFf4GalOk4EcLfcMAhK95TejTXNOkUdJbCaLJnSwAXoJjtUCVKRxwdG+3xnfal2sMH/n9aPou9Kx5xuoPgEl+0rHf0GbbooAM1hqHllDnLpfG+MrCV7FCypxFTrwFekL742gGu+E+z+bXxoWOcH2jGZ5wr708qU99EV3GekMAyKy7mNL1WM/6I9UXHMHvgzQQJVrCx7ZDDZsrhIkFaJXdcP7ZDomMsraI7+mteIKJr+hoMSB+Diurt/Il7jtAGz2yerAW09oEmUAwlFdTQdP0g/EVGrxrcTJn9Hlp07Vpkfusq4QuSsF/JDluZWbWQtaFAbb8Uy+j+DU02jHh25FL78/1e4AWHDvdyJjBX22U3tFldx9ia1N11wQQn7qYoFCyvQBxdEU6ipTUKI2674Sp4rbQ4SUbwf70v8avfx3dBKFMzf0sKkMiXJJQ+CGxJBbyjbVE1EcWFMdHFRuWUgSUhgIpPZl9H+HwBTNFZ4U4GMnc1DkY1Atmqfbe8jMYPs8rSYcjNOlGBl8D/O762wMUFLWm29+DU3qWE762n7gjSjQG57diROYmcxdRF6jlPEHz4PaMkRKu20tlQJTxCiYb++FIlJ9Mq0p5AEUh7nViU52OFOxzH3PMp+vxUUknBcF3WJjGRkvce6fuDKHm/9ZlshFlDI9FHzTAyz05m+bS0H36MrR6hfcUgJvqwfnfUlGoKEFwaY4322HOTHHrgBMzcjCVypQkvY86sSwRwgU2qQWJ0NbOlniNvwcN692uYkhAKxHWWToRygkkzj3XqnlPd7+wvf5aue8AI7XI7LxdPRrt3vge9N5Tc5sLOXXkZgj1n5QXuO2y4UcQa2c+bd+DMMwq23CAvpG5CT8I z4mXGBSE zgHKoaLABLnf+1yN9RSf1pRXDaTpo3yfgzdSQTyziu3SJctlDnX4QkUM9eperdzCLO+AiC4BfD91dh99VbsiTaWRwxenwBTZ4386Oom2RQhj25lP2gVVGCQRdEuiKrjjAfGS5YORkx0TTOhNKdvBcWks4L5tQchqtx7mNn4dePSOETKNQrPqJiB0+guYN1WTGtvtkPAGkwJWdZ9E= 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: February 10, 2023 3:58 PM, "Vlastimil Babka" wrote:=0A= =0A> On 2/10/23 03:51, Yajun Deng wrote:=0A> =0A>> February 10, 2023 10:3= 3 AM, "Yajun Deng" wrote:=0A>> =0A>>> February 10,= 2023 10:14 AM, "Zi Yan" wrote:=0A>> =0A>> On 9 Feb 2023= , at 20:57, Yajun Deng wrote:=0A>> =0A>> February 9, 2023 11:50 PM, "Zi Y= an" wrote:=0A>> =0A>> On 9 Feb 2023, at 5:11, Yajun Deng= wrote:=0A>> There is no need to execute the next loop if it not return i= n the first=0A>> loop. So add a break at the end of the loop.=0A>> =0A>> = Can you explain why? If it is the case, MIGRATE_UNMOVABLE cannot fall bac= k=0A>> to MIGRATE_MOVABLE? And MIGRATE_MOVABLE cannot fall back to MIGRAT= E_UNMOVABLE?=0A>> And MIGRATE_RECLAIMABLE cannot fall back to MIGRATE_MOV= ABLE?=0A>> The return in the loop is only related to 'order', 'migratetyp= e' and 'only_stealable'=0A>> variables. Even if it execute the next loop,= it can't change the result. So the loop=0A>> can be broken if the first = loop can't return.=0A>> =0A>> OK. Got it. Would the code below look bette= r?=0A>> =0A>> for (i =3D 0; i < MIGRATE_PCPTYPES - 1 ; i++) {=0A>> fallba= ck_mt =3D fallbacks[migratetype][i];=0A>> if (free_area_empty(area, fallb= ack_mt))=0A>> continue;=0A>> }=0A>> =0A>> if (can_steal_fallback(order, m= igratetype))=0A>> *can_steal =3D true;=0A>> =0A>> if (!only_stealable || = *can_steal)=0A>> return fallback_mt;=0A>> =0A>> return -1;=0A>>> Yes, I'l= l submit a v3 patch.=0A>>> Thanks.=0A>> =0A>> I found a logical error in = your code. It should be like this:=0A>> =0A>> for (i =3D 0; i < MIGRATE_P= CPTYPES - 1 ; i++) {=0A>> fallback_mt =3D fallbacks[migratetype][i];=0A>>= if (!free_area_empty(area, fallback_mt))=0A>> break;=0A>> }=0A>> =0A>> i= f (can_steal_fallback(order, migratetype))=0A>> *can_steal =3D true;=0A>>= =0A>> if (!only_stealable || *can_steal)=0A>> return fallback_mt;=0A>> = =0A>> return -1;=0A>> =0A>> This code will modify the logic to the opposi= te.=0A> =0A> It's still wrong, IMHO. If all fallbacks have free_area_empt= y(), it will=0A> return the last one and not -1. Also will set *can_steal= in such case.=0A> =0A=0AYes, you are right.=0A=0A>> So can anyone tell m= e if I should use this code or the v2 patch?=0A> =0A> Once that bugs are = fixed, the result will probably not look much better than=0A> v2, so I do= n't mind keeping v2.=0A=0AI agree with that.