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 789C3D41C07 for ; Wed, 13 Nov 2024 06:15:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 120796B00AF; Wed, 13 Nov 2024 01:15:03 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0D0D16B00B0; Wed, 13 Nov 2024 01:15:03 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F01336B00B3; Wed, 13 Nov 2024 01:15:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id D1D066B00AF for ; Wed, 13 Nov 2024 01:15:02 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id F0D48AC096 for ; Wed, 13 Nov 2024 06:15:01 +0000 (UTC) X-FDA: 82780057584.24.8A0F4F0 Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) by imf27.hostedemail.com (Postfix) with ESMTP id 74F1340007 for ; Wed, 13 Nov 2024 06:14:16 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=QGoQpMB4; spf=pass (imf27.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=hao.ge@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=1731478266; 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=iznfGCpYbJwUp5ETkMWKQlT7qKI0pW/GHJyy2cYs/dc=; b=54pG921HD6wTZS986YGP0+HcCdxEI0m1QDpXYpL/Qyb2LlsxL3Vliif3VoHn+ihgiCONlp UlOf8NSY4cqFGb7i6EPaOlt3fh8/Ul4qZwWNA+XIZ4Hva2h2EBmLojJUArumt15yRmarey RtwiKq5/Vm2rHGMBSTm8D1TTconEsuM= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=QGoQpMB4; spf=pass (imf27.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=hao.ge@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1731478266; a=rsa-sha256; cv=none; b=WuWZBvC6nvz4gtdD6Y0vVlRabX9Taxa/CDchRzmy5BGkrrQF/ARF5cpyOyxlz2uEEGfsQX J2qQo3vBsDAOmonL1LEaM70MEmlnDPNBXFiJjew6+Nou8xlYVUXeLXrYGansbXi+frFbec xxO5hPBhpJE7vncx/Ajp0AKKZ13afJc= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1731478498; 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=iznfGCpYbJwUp5ETkMWKQlT7qKI0pW/GHJyy2cYs/dc=; b=QGoQpMB4YgFerLeeRk2DN/3v3YRAEtXtw0Dy/PjKhdfVk+Yxy8MSsCb+/d3OGU6SRkUBJZ JAKKHhnluLLmpD+YrWrlP/TT2pUZKhVEqMsdhXa7TTEIXkTiG4of7+OkslOAIA5sn7pIcP sRg4V2bHcbQrLkGuIlh083c1Qg2zeqw= Date: Wed, 13 Nov 2024 14:14:27 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] lib/alloc_tag: Remove the sysctl configuration to prevent users from disabling it at runtime To: Kent Overstreet Cc: Suren Baghdasaryan , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hao Ge References: <20241108075004.131911-1-hao.ge@linux.dev> <71703c20-8311-ce3f-fbed-27d2ec3a2c82@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Hao Ge In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 74F1340007 X-Stat-Signature: 119ftx7jt73qqroydqkcr6ecn716ui9j X-Rspam-User: X-HE-Tag: 1731478456-102695 X-HE-Meta: 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 UEhAdffz FYVyStuoDgGcAJEhXXRwbHq3sLLernr0vfjs3hGPfJVmqUfttPaYrrwRtLfNthBkiNq53a2fMS7ZMK0WM4sS1Jdcjm2N+ifb0F02gYVHIYEfGdcmTDaFQygDOs3a3ihwQZE1AMKzQk0C6WrkWEZqRCx2R3qKZMnBISBc5js86v5LV95Y9h1hTmJIXYSdipbBzE74ajWOSFH92uvMz+sLxqQFgoNlFI84ofxBI 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: List-Subscribe: List-Unsubscribe: On 11/13/24 02:14, Kent Overstreet wrote: > On Tue, Nov 12, 2024 at 11:30:39AM +0800, Hao Ge wrote: >> Hi Suren >> >> >> Firstly, please forgive me for my improper wording in the commit message. >> >> After sending it, I realized that I should have used "suggestion" instead of >> "decided". >> >> Secondly, please forgive me for taking a few days to respond. I've been >> quite busy these days. >> >> >> Let's continue to discuss this issue. >> >> >> On 11/9/24 02:16, Suren Baghdasaryan wrote: >>> On Thu, Nov 7, 2024 at 11:50 PM Hao Ge wrote: >>>> From: Hao Ge >>>> >>>> After much consideration,I have decided to remove >>>> the "mem_profiling" sysctl interface to prevent >>>> users from dynamically enabling or disabling the >>>> MEMORY ALLOCATION PROFILING feature at runtime. >>>> >>>> I have taken the following actions: I set >>>> CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y to >>>> enable memory allocation profiling by default, >>>> and then made adjustments to mem_profiling dynamically >>>> during runtime. >>>> >>>> When I ran the OOM test program, I obtained useful >>>> information that was indeed very helpful for debugging. >>>> >>>> [ 1023.065402] Memory allocations: >>>> [ 1023.065407] 12.8 GiB 6546 mm/huge_memory.c:1328 func:do_huge_pmd_anonymous_page >>>> [ 1023.065412] 873 MiB 229985 arch/arm64/mm/fault.c:986 func:vma_alloc_zeroed_movable_folio >>>> [ 1023.065415] 187 MiB 29732 mm/slub.c:2412 func:alloc_slab_page >>>> [ 1023.065418] 99.8 MiB 25560 mm/memory.c:1065 func:folio_prealloc >>>> [ 1023.065421] 47.2 MiB 3189 mm/readahead.c:434 func:ra_alloc_folio >>>> [ 1023.065424] 30.0 MiB 15 mm/khugepaged.c:1072 func:alloc_charge_folio >>>> [ 1023.065428] 28.6 MiB 514 mm/compaction.c:1880 func:compaction_alloc >>>> [ 1023.065430] 25.8 MiB 6592 mm/page_ext.c:271 func:alloc_page_ext >>>> [ 1023.065433] 25.6 MiB 6546 mm/huge_memory.c:1161 func:__do_huge_pmd_anonymous_page >>>> [ 1023.065436] 23.5 MiB 6017 mm/shmem.c:1771 func:shmem_alloc_folio >>>> >>>> After running echo 0 > /proc/sys/vm/mem_profiling >>>> and then executing the same test program, >>>> I obtained the following results >>>> >>>> [ 1156.509699] Memory allocations: >>>> [ 1156.509703] 187 MiB 29645 mm/slub.c:2412 func:alloc_slab_page >>>> [ 1156.509707] 142 MiB 9357 mm/readahead.c:434 func:ra_alloc_folio >>>> [ 1156.509710] 136 MiB 41325 arch/arm64/mm/fault.c:986 func:vma_alloc_zeroed_movable_folio >>>> [ 1156.509713] 99.7 MiB 25531 mm/memory.c:1065 func:folio_prealloc >>>> [ 1156.509716] 56.0 MiB 28 mm/huge_memory.c:1328 func:do_huge_pmd_anonymous_page >>>> [ 1156.509719] 30.0 MiB 15 mm/khugepaged.c:1072 func:alloc_charge_folio >>>> [ 1156.509723] 28.6 MiB 514 mm/compaction.c:1880 func:compaction_alloc >>>> [ 1156.509725] 26.3 MiB 7460 mm/readahead.c:264 func:page_cache_ra_unbounded >>>> [ 1156.509728] 25.8 MiB 6592 mm/page_ext.c:271 func:alloc_page_ext >>>> [ 1156.509730] 23.5 MiB 6016 mm/shmem.c:1771 func:shmem_alloc_folio >>>> >>>> Because mem_profiling was disabled by executing >>>> echo 0 > /proc/sys/vm/mem_profiling,we are unable to >>>> record memory allocation information after the disablement. >>> Naturally you are unable to track the allocations after disabling it. >>> You disabled it as root, so I assume you know what you are doing. >>> >>>> These output logs can mislead users. And similarly, the same >>>> applies to alloc_info. >>> I would understand if you made /proc/allocinfo empty after disabling >>> it to avoid confusing the user, but ripping out the ability to >>> enable/disable profiling at runtime does not make sense to me. Once >>> you collect required data, disabling profiling gets you back the >>> performance that you pay for it. There are usecases when a program on >>> a remote device periodically enables profiling for some time, records >>> the difference in allocations and then disables it. Your change breaks >>> such users. >> >> Actually, my original intention was also to make /proc/allocinfo empty when >> disabling it, >> >> but I considered the following scenario: after we disable it and clear >> /proc/allocinfo, >> >> we then start a memory-intensive application, >> >> such as our OOM (Out-Of-Memory) test program. >> >> If we later enable it again, the issue described in my commit message would >> still arise. >> >> Perhaps we need to further consider how to handle this situation. > Why would you do such a thing? > > We put a lot of effort into making memory allocation profiling cheap > enough to leave on, and I haven't seen a single complaint about > performance overhead. Hi Kent Thank you very much for your and Suren's hard work. For me, this feature is still very useful As I mentioned in my previous reply to Suren's email, I did overlook some things, and for that, I apologize. Thanks Best regards Hao