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 CDAB8CA0EE0 for ; Wed, 13 Aug 2025 16:17:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2D6AB9000A9; Wed, 13 Aug 2025 12:17:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2AE59900088; Wed, 13 Aug 2025 12:17:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1C4719000A9; Wed, 13 Aug 2025 12:17:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0B068900088 for ; Wed, 13 Aug 2025 12:17:13 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id AEA23137EAE for ; Wed, 13 Aug 2025 16:17:12 +0000 (UTC) X-FDA: 83772238704.29.B25C16C Received: from mail-qk1-f171.google.com (mail-qk1-f171.google.com [209.85.222.171]) by imf27.hostedemail.com (Postfix) with ESMTP id B477240004 for ; Wed, 13 Aug 2025 16:17:10 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=In9cU0gt; spf=pass (imf27.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.222.171 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755101830; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=y0r8lX0/1M6KsfijF5/m66QhjeQjFJTvODKoUvnEDMw=; b=2gtNNSSSIsJCn8l7FxQTZwQ5nEr0MQJSBVGlIQkJMIAqdYnd5SYj86nr1VbUN8zXVTDpY3 XMHNzKXeysmCCAuzvgEz5Lx/wZrU7BG/CSRcfX8ZN952e/bUpirPmGCevzvSbKPf7d2uDT wc9u82jrJqyPf1AsDrJR6qbTZhM0xCA= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=In9cU0gt; spf=pass (imf27.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.222.171 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755101830; a=rsa-sha256; cv=none; b=Y5mn1lB7DTRK/IuhpUOuUY7PcSd7qlL4Mb9/bUPWm2jpuJ+Vmn52CDh0HG8uwaeyPkdWgW Cs7Z/Flc34LgQb060JSGY563zABM3XE5nkIAMiX+SaAizOgW2iddNRY7c1QWAGkGsmpQaj y8/1h74a3bKvsZFU/Iz3QaEXfIh9prg= Received: by mail-qk1-f171.google.com with SMTP id af79cd13be357-7e62a1cbf82so478770185a.2 for ; Wed, 13 Aug 2025 09:17:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1755101830; x=1755706630; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=y0r8lX0/1M6KsfijF5/m66QhjeQjFJTvODKoUvnEDMw=; b=In9cU0gtUXHyMraglkh73efDg4kQUiWcRS9UcDHRsfOypYvdfeGcNL7TwAC92HDray qqvqO+jzdouTqho5qNdX/l3bR6DJr66reuAfPgyUSvW9dJqPRUetKqy+uuN2bEK0wttR UDQlk02iwI0jkocrTrB9h0XQkHYtQFcHa6nFob97kpPZxHoyM9K0JgvheXolnHba23kI i0BXSjlK9+ARF7BoRDQzrdWyYbB/hVzDiHrQJIJg4vwJe8AEZa5j6oeL4t7ZhB38dbx9 M6QPtun/EUEgEbyBljY/QBVRcWDylAywBl6vxccD2tsTqItuHL4WykvQDJFJhihpaa2A jojw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755101830; x=1755706630; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=y0r8lX0/1M6KsfijF5/m66QhjeQjFJTvODKoUvnEDMw=; b=fzzSRh7UiiZj3yIRYOMfzX437UDKuDM6i2J0HAnKMrPREAL0pNRZiUG2IzHpFWLyTU PmaOmSOUUMD+zZxCnbvvhOKaSrf7qcmNI37MMjAS68uToI/pCVAsveXIqc7hT79yi/xK KbwxCrHKjq1iOOw3GliR98yLSXnCC44PrHjf+UItAwk+wZLLDwcrLvdFZOsgMQqImTdm xG4LniUbj0VyfUdANo2UDRAvINPNr/+bUM8S0XrU6RGY8CJcLOXem+9XVMlx1NTxM1R+ iJVoYVxrD2YM7h7W8lAPd2aQf9dLec9QQeU1uGUumZx+Ky4GXA+Vx5zg29R+CDWmIXKb ntuA== X-Gm-Message-State: AOJu0YyiQjKB8Bcyd+p35A9cQNyaXAZjMvd/5mY9Zldu99dYQ9o+QRhB KeXSiOIL34gs02NgGkUhcmcKJuw1YLItlkp0d3jpmSmLNe2g5UYLFAvYVhHl1AcxaBs= X-Gm-Gg: ASbGncu7rstFWZ7QySlV2OI+PzBTwIfy95lNdkXPBVmp+7xg2eOU9zig404/3P9Zjkc jY1IjJOEWh+QDSQOEsFl+9RZy7A/NADUs5FZss4LLdEA3ub3qjYu/UgQ9JaFo4a1vRbtGO3qORj UPzDLUiISkqukAge6E/dzCbtc2osVEQSNiHpSEEHB7XXh8Y5UPNg7Q9gYHFmSGHhejJoGIgzLq/ tY1sn17oSctV9/SPq6TIc1DIlh7NdRBQUQz+70Gt9qOqNHO6Z9MPzgc/wTRDy6xhVS0VCqFTxTe aWZ2Xdw1u51V0q0qxB+Q0JSNsOFzALDJo57+ksimetoe9xgdAtpvOD067Zq+H1hw6CIaailiP9i wqvJRfsDUJxYNNwG3nnEb4g== X-Google-Smtp-Source: AGHT+IGHCZVUArn+hQTSYfm5ZLOiQRAX3EihSL5rOgIAp2pUobtvdJENs5NTWAKywrm2ri8umYv+Hw== X-Received: by 2002:a05:620a:560d:b0:7e0:e7b0:967e with SMTP id af79cd13be357-7e86522c104mr386843385a.7.1755101829593; Wed, 13 Aug 2025 09:17:09 -0700 (PDT) Received: from localhost ([2603:7000:c01:2716:929a:4aff:fe16:c778]) by smtp.gmail.com with UTF8SMTPSA id d75a77b69052e-4af230d8a21sm153187231cf.51.2025.08.13.09.17.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Aug 2025 09:17:09 -0700 (PDT) Date: Wed, 13 Aug 2025 12:17:08 -0400 From: Johannes Weiner To: Thomas Gleixner Cc: linux-mm@kvack.org, LKML , Peter Zijlstra , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , cgroups@vger.kernel.org, Andrew Morton Subject: Re: [PATCH] memcg: Optimize exit to user space Message-ID: <20250813161708.GA115258@cmpxchg.org> References: <87tt2b6zgs.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87tt2b6zgs.ffs@tglx> X-Rspamd-Queue-Id: B477240004 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: 3but1hjbzzpy3nhj6d5u47hpyjywqwts X-HE-Tag: 1755101830-346267 X-HE-Meta: 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 aTxMkjgo 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 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 Wed, Aug 13, 2025 at 04:57:55PM +0200, Thomas Gleixner wrote: > memcg uses TIF_NOTIFY_RESUME to handle reclaiming on exit to user > space. TIF_NOTIFY_RESUME is a multiplexing TIF bit, which is utilized by > other entities as well. > > This results in a unconditional mem_cgroup_handle_over_high() call for > every invocation of resume_user_mode_work(), which is a pointless > exercise as most of the time there is no reclaim work to do. > > Especially since RSEQ is used by glibc, TIF_NOTIFY_RESUME is raised > quite frequently and the empty calls show up in exit path profiling. > > Optimize this by doing a quick check of the reclaim condition before > invoking it. > > Signed-off-by: Thomas Gleixner > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Roman Gushchin > Cc: Shakeel Butt > Cc: Muchun Song > Cc: Andrew Morton Nice! Acked-by: Johannes Weiner