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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1FC47EE6B4D for ; Fri, 6 Feb 2026 20:11:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 498BC6B0089; Fri, 6 Feb 2026 15:11:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 446DC6B0092; Fri, 6 Feb 2026 15:11:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3455E6B0093; Fri, 6 Feb 2026 15:11:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 1E1EA6B0089 for ; Fri, 6 Feb 2026 15:11:58 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id B96AC8B150 for ; Fri, 6 Feb 2026 20:11:57 +0000 (UTC) X-FDA: 84415127874.30.B725C10 Received: from relay.hostedemail.com (unirelay08 [10.200.18.71]) by imf23.hostedemail.com (Postfix) with ESMTP id B6C9D140008 for ; Fri, 6 Feb 2026 20:11:55 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; arc=pass ("hostedemail.com:s=arc-20220608:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770408715; 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=mom4FxigxUqgxHxI6Kp9ws79L6QLBt12tfLMkhAQPhM=; b=2R2SIqNgZYVzltrIrgabEqyENtWZa0G4aZlwM6c3nOvnQR1fkuzzvyrRfoNo3mgdtewdRd BZNKjOd+YabSf/qnaj3x2ie9VKMXtpzWiANlaSMn30E497JmQRcCEDXoNZ4wFWG+2KW+WZ bgEm0kEKhWKTgHaYQYNz5OSJz/8XsbM= ARC-Authentication-Results: i=2; imf23.hostedemail.com; arc=pass ("hostedemail.com:s=arc-20220608:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1770408715; a=rsa-sha256; cv=pass; b=YkfepXbtsLN0IFJFQOKRh1va+yD7l3a5HIXV7rAelboF3eZb4pk1hIhAJPkhbjxZHpzS2Y EwAYyqEVyCzRx1wK7XIGwOODP5sM7Y2wZixOgs9gQWF3ufJTFj8BTPtzhl6R6NsIs+EMJ6 orFIN60jLKL4BVnp1JGIjA6heotycv0= Received: from relay.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 4561B140321 for ; Fri, 6 Feb 2026 20:11:55 +0000 (UTC) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 1588E1A02D7 for ; Fri, 6 Feb 2026 20:11:55 +0000 (UTC) X-FDA: 84415127790.26.C1BFC2F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 55FE4A0008 for ; Fri, 6 Feb 2026 20:11:53 +0000 (UTC) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770408713; 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=mom4FxigxUqgxHxI6Kp9ws79L6QLBt12tfLMkhAQPhM=; b=kncY76J/QB4kmkGq3cJHP1J7iH7eiK4mQeHzF9gq6Xo/qexkbsn8T7ApVwoug3kgQ8X1jF fYqUQ28XsAzL4OIJHd8yXbkrVxEDQ81f/3H0a3k9jm//hWRRtpUc/OPJQlJw6XlyHUv5z9 Lv7aLNzUmaJrlJplCKq4Kz8v1/An5T8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=z+sCdjyQ; spf=pass (imf25.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770408713; a=rsa-sha256; cv=none; b=tqM7ZLgO3x/RcYc/AeJCUn6F73u1I0aTQXRYsincm/tLT+RXVO6GeZ1hqd4FfM51ji9OJz DqXo9PoLK1I7OyYp7ie4grjkVhRLusbLPVE5lpfz9Qimg27rih9P19bxZVc0CJFBCnDfyw p+ySey3e31wEgGA2NSVreFHahUlIUKk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 157FB401F2; Fri, 6 Feb 2026 20:11:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF525C116C6; Fri, 6 Feb 2026 20:11:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1770408711; bh=8mYM8u1acZ5xGe1Ak0y+3i5xy3haa0EvTTtCBilST0U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=z+sCdjyQIdGmSGapZlqU23+BnFvm+eBV19oig3SG1wvDSaouD5eAGZqVmGAurEB0z kT0664BuT7Vdxd4kEZ1SXzRFtkzLQZurOoFzWGRAyzW5G284lPcuAgEQ535Lv4Wmey Bq/PxNalbxIcQTIC0/7boFsZfpuxvaUZa15Ix8Hc= Date: Fri, 6 Feb 2026 12:11:51 -0800 From: Andrew Morton To: carstengrohmann@gmx.de Cc: bugzilla-daemon@kernel.org, Kairui Song , Baoquan He , Nhat Pham , Yosry Ahmed , linux-mm@kvack.org Subject: Re: [Bug 221055] New: Hibernate image write 10x slower since commit 0ff67f990bd4 ("mm, swap: remove swap slot cache") Message-Id: <20260206121151.dea3633d1f0ded7bbf49c22e@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-HE-Meta: U2FsdGVkX1820Ie0vkXrCLFeeVwS+PuZyJL8sy2OGfFH6Xz7gsskYj2vYztZn++Dd/KFrO373Pv9AKMfJ/0Y5OxUtxc60/hrS0N1odPlw8lpjXA8J3yazlHXOE87dEzN8PDzTn2VpKzhsERpWWFi+ED6e3WDHz7wX0K5iKuQTlNgDGl38V7VVIO5QcFrG2QiDzQPOxptbvCadc3zkfpEhB4xm75P1js++cnyLuYGnJgLmcC7K9aCl7QML80jaqh0VWkSWhmlFP7+2YzDBKlhWs4bc1XSLj5Z+1raEcK9UQoOwGWpzUcmGhGdNireAityRMnjKmQ7LWgG8mX3CB1oUxjeWJJkheyIW+Rs2gX1vRsT4LbdkMhMAPor6CAvEBfJnHRwtaiPcyrwechlQlieUysrwsq1ICPx6O2Eg9IMuK4aFe8MAZwagArbkn9FrE9RDDy7SRSK0STXKE0qB468cfl7XAB8Y2JTnYMMacmzEflQ5nwQNS1cO/HoXjSP/H2ZxsygVpiCtrVSg1mk+8wJgdkdzsWs+Lz1o9FOYT0VkoSYsElytK8k4a2Y+XFzDQtXWzjpL7ZcCxdVub7+HXL5zMaAgJ2QSjVQm904VzTDbM3rsazh6M/dgucyJXi3xDUR/McyxbfKq6sdH/1VhJ9gBN3m6+pfVSZzkZ6+5otLDZwzG0j9Kcx8iCYufcQSPBCh5KG4Qb/KlhJodT8SpmqrOYLdWQ5+FNM6cyTQ8He5HYvaPH24MjpVhxS8K/vXYivFC5ll2s/px2UhTKTYyGFW8tfzMkTex0JN73CE+20U3eqixgLmdMGqxKcmvxQ9oRW/2H9dwjBCZVAzdc+wH6FzkReUexbSUHPqoRXhlfAcEWtS14jowZkArniwvVpTa8Lgnsque1Wtc7TJ9wf85gPZzfc9YTYtr+vnwkEucqyzDpU= X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B6C9D140008 X-Stat-Signature: 5refud5zyfgjec57qa6n83aiws6w3djs X-Rspam-User: X-HE-Tag-Orig: 1770408713-649919 X-HE-Tag: 1770408715-186357 X-HE-Meta: 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 kor2CVHV xwFEC3UV3sd712NGtP7P0Z5GW108FqRaEcGEgTEXzeRQRMjJ0yj0hDR7W+XLkIZjlqE2gX4dIMWkgFDZBJeLGfeRUBhmCjILl8kRN2MHp09CUqrbqFYml7yaz7U9OBxZAIWeXM31x9vYoA7WazacGjWUzYsPztBmA1EfucyipCsjptApmCBEQ+KRfk2v143oeusFPEKdKwxoDPeI+FCLytFb1/G7Jb6KX0WrKqecOt2xgzcklSnHVAcCixI0eyq4cweE63Y8rVWsJTik= 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 Fri, 06 Feb 2026 19:51:38 +0000 bugzilla-daemon@kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=221055 Dear Deity, I do wish kernel MM bugzilla would just go away. Sigh. Canned response follows: (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). > Bug ID: 221055 > Summary: Hibernate image write 10x slower since commit > 0ff67f990bd4 ("mm, swap: remove swap slot cache") > Product: Memory Management > Version: 2.5 > Hardware: All > OS: Linux > Status: NEW > Severity: normal > Priority: P3 > Component: Other > Assignee: akpm@linux-foundation.org > Reporter: carstengrohmann@gmx.de > Regression: No > > === Summary === > > Hibernate image write 10x slower since commit 0ff67f990bd4 ("mm, > swap: remove swap slot cache") Thanks for all the work you put into this. > === Description === > > Since kernel 6.15, writing the hibernate image to swap has become > approximately 10x slower. The regression was introduced by commit > 0ff67f990bd45726e0d9e91111d998e7a3595b32 ("mm, swap: remove swap slot > cache") authored by Kairui Song and merged by Andrew Morton. > > === Performance Data === > > Before (6.14) After (6.15+) > Hibernate 28-32 seconds 290-342 seconds > Effective rate ~60 MB/s ~4.5 MB/s > > The swap partition's raw sequential write speed (measured with dd) > is 255-450 MB/s, confirming the hardware is not the bottleneck. > > === Bisect Result === > > A full git bisect on the vanilla kernel repository > (git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git) > between v6.14 (good) and v6.15 (bad) with 14 iterations > consistently identified this commit: > > # first bad commit: [0ff67f990bd45726e0d9e91111d998e7a3595b32] > # mm, swap: remove swap slot cache > > The parent commit 1b7e90020eb7 ("mm, swap: use percpu cluster as > allocation fast path") is fast (28s), while 0ff67f990bd4 itself > is slow (307s). > > === Kernel Version Tests === > > Kernel Duration Result > 6.12.1-arch1-1 32 sec OK > 6.13.1-arch1-1 42 sec OK > 6.14.1-arch1-1 32 sec OK > 6.15.1-arch1-1 302 sec SLOW > 6.18.1-arch1-1 290 sec SLOW > > === Reproduction === > > 1. System with swap partition (not swap file) > 2. Boot kernel >= 6.15 > 3. Run: echo reboot > /sys/power/disk > 4. Run: echo 1 > /sys/power/pm_print_times > 5. Run: date; echo disk > /sys/power/state; date > 6. Compare hibernate duration with kernel <= 6.14 > > For best visibility of the issue, use hibernate=nocompress as > kernel parameter to disable image compression. > > === Hardware === > > - CPU: Intel Core (Ivy Bridge) > - RAM: 16 GB > - SSD: Samsung SSD 830 Series (SATA II, 3.0 Gbps) > - Swap: 20 GB partition (/dev/sda2) > - Arch Linux x86_64 > > === Kernel Log (6.18, with hibernate=nocompress) === > > PM: hibernation: hibernation entry > PM: hibernation: Preallocating image memory > PM: hibernation: Allocated 2217260 kbytes in 0.39 seconds (5685.28 MB/s) > PM: hibernation: Creating image: > PM: hibernation: Need to copy 506945 pages > PM: hibernation: Wrote 1794356 kbytes in 397.97 seconds (4.51 MB/s) > > -- > You may reply to this email to add a comment. > > You are receiving this mail because: > You are the assignee for the bug.