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 48FA8CDB474 for ; Mon, 16 Oct 2023 08:10:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A1A7F8D0028; Mon, 16 Oct 2023 04:10:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9CB548D0001; Mon, 16 Oct 2023 04:10:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E2418D0028; Mon, 16 Oct 2023 04:10:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7FAF28D0001 for ; Mon, 16 Oct 2023 04:10:47 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 4E49C1A0B0F for ; Mon, 16 Oct 2023 08:10:47 +0000 (UTC) X-FDA: 81350603334.13.C32DDE5 Received: from out-197.mta1.migadu.com (out-197.mta1.migadu.com [95.215.58.197]) by imf05.hostedemail.com (Postfix) with ESMTP id 5D110100005 for ; Mon, 16 Oct 2023 08:10:44 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=nnR1GG0x; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf05.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.197 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1697443845; a=rsa-sha256; cv=none; b=PJP+F4Ugyia1JxdMlPExviYL4bDHmz+4k4hmwWtmTcTeP2uLmw9eupEXy3NISUQ1tR8xnY STsmTfuYDbHmO/dKNp/aYbaadktxm9V4HfTyQ7XIWgoxyhfIAX0EVNeDeFtP8fSgtmxCIe A7PkJ2gw/bGhlv9/cVLKXqFGGu7pJjQ= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=nnR1GG0x; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf05.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.197 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1697443845; 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=Ftz3kg8fbbtLXGwBLfTxu3Gnc6ZKz1jBxA85bC9wrOk=; b=fUvvMa2mUiQqoKN7WTkgKuGxUpujIqFp/BXOYRYW5p03WQk/uHeCAuxA0j6aazd0+ZcFbB qZmRm4KSrze3fT0nFPm3wM91UD6K6QJ3e7lq5Yf6UH63qW8wuW1E062QU5PQF2KhCLH2Sa FxUg74VC1aovxZItrIhxpKQYTcsV6eA= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697443840; 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=Ftz3kg8fbbtLXGwBLfTxu3Gnc6ZKz1jBxA85bC9wrOk=; b=nnR1GG0xec5M/KvAHK28cBptgNPCmVGOaZjqotTcoVDzPs80vU8ciWHo/TiVLDz7x74rF9 cJLTrH2lARxwGUIkiSLvuS9AbZ5+yKLJ3LoWPu+cvyBMXBW1uDllFBFIZ8ddSn0U0GQ6IW TxWJp5fT9c+O1BPNTmY6OVv7uTy/oZQ= Date: Mon, 16 Oct 2023 16:10:30 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY Content-Language: en-US To: Mike Rapoport Cc: David Hildenbrand , akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230928083302.386202-1-yajun.deng@linux.dev> <20230928083302.386202-3-yajun.deng@linux.dev> <20230929083018.GU3303@kernel.org> <2f8c4741-5c7f-272d-9cef-9fda9fbc7ca6@linux.dev> <5382bf2d-5aa0-1498-8169-3248be4b5af3@linux.dev> <38cd0cb9-efe9-b98a-2768-ccb48da8b812@linux.dev> <20231013084827.GT3303@kernel.org> <1c91dd62-886d-bb05-8aee-22191a8a2d8e@linux.dev> <20231016063357.GU3303@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yajun Deng In-Reply-To: <20231016063357.GU3303@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5D110100005 X-Stat-Signature: yu9emfqewho7b88boscxg1p57acdqxus X-HE-Tag: 1697443844-977865 X-HE-Meta: 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 E0TOcoOx +daa4JJC7Zg4TJdY30Fl7U26Y2igVgMsMRbs9KfGcg45+HjbBHCDMdWLZaFdXk3jKCxem5iRKcQBoW7347qK45Sihiw3O24NER13ss5tc6mcfCJPV2kZZf0YqzcZTLrAKu1YFOv8YhB/a3Nk14zKKAdQgYhlpZ+vI5NqCT92H4pPnouvPeb0AzzLebuhIpc3TIQY2 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 2023/10/16 14:33, Mike Rapoport wrote: > On Fri, Oct 13, 2023 at 05:29:19PM +0800, Yajun Deng wrote: >> On 2023/10/13 16:48, Mike Rapoport wrote: >>> On Thu, Oct 12, 2023 at 05:53:22PM +0800, Yajun Deng wrote: >>>> On 2023/10/12 17:23, David Hildenbrand wrote: >>>>> On 10.10.23 04:31, Yajun Deng wrote: >>>>>> On 2023/10/8 16:57, Yajun Deng wrote: >>>>>>>> That looks wrong. if the page count would by pure luck be 0 >>>>>>>> already for hotplugged memory, you wouldn't clear the reserved >>>>>>>> flag. >>>>>>>> >>>>>>>> These changes make me a bit nervous. >>>>>>> Is 'if (page_count(page) || PageReserved(page))' be safer? Or do I >>>>>>> need to do something else? >>>>>>> >>>>>> How about the following if statement? But it needs to add more patch >>>>>> like v1 ([PATCH 2/4] mm: Introduce MEMINIT_LATE context). >>>>>> >>>>>> It'll be safer, but more complex. Please comment... >>>>>> >>>>>>     if (context != MEMINIT_EARLY || (page_count(page) || >>>>>> PageReserved(page)) { >>>>>> >>>>> Ideally we could make initialization only depend on the context, and not >>>>> check for count or the reserved flag. >>>>> >>>> This link is v1, >>>> https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/ >>>> >>>> If we could make initialization only depend on the context, I'll modify it >>>> based on v1. >>> Although ~20% improvement looks impressive, this is only optimization of a >>> fraction of the boot time, and realistically, how much 56 msec saves from >>> the total boot time when you boot a machine with 190G of RAM? >> There are a lot of factors that can affect the total boot time. 56 msec >> saves may be insignificant. >> >> But if we look at the boot log, we'll see there's a significant time jump. >> >> before: >> >> [    0.250334] ACPI: PM-Timer IO Port: 0x508 >> [    0.618994] Memory: 173413056K/199884452K available (18440K kernel code, >> >> after: >> >> [    0.260229] software IO TLB: area num 32. >> [    0.563497] Memory: 173413056K/199884452K available (18440K kernel code, >> Memory: >> Memory initialization is time consuming in the boot log. > You just confirmed that 56 msec is insignificant and then you send again > the improvement of ~60 msec in memory initialization. > > What does this improvement gain in percentage of total boot time? before: [   10.692708] Run /init as init process after: [   10.666290] Run /init as init process About 0.25%. The total boot time is variable, depending on how many drivers need to be initialized. > >>> I still think the improvement does not justify the churn, added complexity >>> and special casing of different code paths of initialization of struct pages. >> >> Because there is a loop, if the order is MAX_ORDER, the loop will run 1024 >> times. The following 'if' would be safer: >> >> 'if (context != MEMINIT_EARLY || (page_count(page) || >> PageReserved(page)) >> {' > No, it will not. > > As the matter of fact any condition here won't be 'safer' because it makes > the code more complex and less maintainable. > Any future change in __free_pages_core() or one of it's callers will have > to reason what will happen with that condition after the change. To avoid introducing MEMINIT_LATE context and make code simpler. This might be a better option. if (page_count(page) || PageReserved(page))