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 03E6BC6FD1D for ; Sat, 1 Apr 2023 11:38:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 797486B0072; Sat, 1 Apr 2023 07:38:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 746D8900002; Sat, 1 Apr 2023 07:38:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 60EA26B0075; Sat, 1 Apr 2023 07:38:42 -0400 (EDT) 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 525D46B0072 for ; Sat, 1 Apr 2023 07:38:42 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 1BCEE1A0F40 for ; Sat, 1 Apr 2023 11:38:42 +0000 (UTC) X-FDA: 80632624884.17.F447F48 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) by imf13.hostedemail.com (Postfix) with ESMTP id 219A22000B for ; Sat, 1 Apr 2023 11:38:37 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=CofTxiuE; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.174 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1680349118; 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=wcCR0zpJu7VQLniCgKfkIUTKj7puFk+BLdwp11svwwU=; b=D9kOO2jlKMz0CeT6CsOjiJwjLqWl9DRxUVnIlNeXm4T6X83kctpwNSqB7Nzk+uwd0IIWDl +AMl87pIkVIZDQiMnLKNuG8QsdymR0Hm/aerD70iWhAS5CZnMj4bU029WSw14Rt/92149b q7zwEdsfh6mSHqJWDn7iB8gXRSFk/r8= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=CofTxiuE; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.174 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680349118; a=rsa-sha256; cv=none; b=F6EWl2c1FUFJxyPqQld7xbOyKAFw5qYOUTg4dzVjNW+4e+9G47pyDHbDmD5OAFzZRKIQ2K EEOC3GqArs2+sl6rphkBHF0C0LM5NvcZtItAUMW3jF0RioxOaxkcTmbVBBRUZALac7vbj2 uyPKg5NZ1oWu8NcgL+2rM/A7MJBHXnM= Received: by mail-pl1-f174.google.com with SMTP id kc4so23815076plb.10 for ; Sat, 01 Apr 2023 04:38:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680349117; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=wcCR0zpJu7VQLniCgKfkIUTKj7puFk+BLdwp11svwwU=; b=CofTxiuEztAUH+5RKda3JyMBHaFnZUxHYxPqOVqfABsMGeDKo0aLimRaT8/9rIxVn7 RtrN07ZwK3nzsqAorzUh/HZTlSyLoUYwuZwFUHvuaA7S6RG3sBqXpBUQvlMP9/B/c61b GnPXv0Kaf4jXkKmgruFwSU1tFL2roJIfDzd/GIk74L6SL1E5gjjIdqBEKZxQGW7ID0S3 vEiJWrmVnZ1xj/y8zOEiu+HeEaD0mfqxfyONzTtMDNCJrHa+WNNOFa8XGs2/ntOC/vX5 d8igbpropDmVIuA6jT6SDdtVfVCLMIdGMxUcEsjIRHTW7LIKkG3dcQW4Sf0y8IttJejF rk+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680349117; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=wcCR0zpJu7VQLniCgKfkIUTKj7puFk+BLdwp11svwwU=; b=zZ0+QhmCeXD01lM49udM0fcWdv0ftrafr9KKioHO2PJXmfwSP8VeqvxLroAI4IfUaT 4urDRMP1Jb3Y3FPoSjQwOHBjlnnaL6dq1WrD6uQhRuCRHYhJNKTpPZgOhoQ8ngtP3/aR LvQbvo2viXPSDKCmhOkqlHRaJo8MiUuCv3zkDpQTN4GQCbkaQAG61iPbICXp+FcsZ0N1 YinK+eZRf9k2sNZmEQnmiv3ZgCE/0Z8wgCVE9w7ooWobncjNrwweXF2QQl6gtM2wokLC DoF/4Se+A6g3AcwWKuY2YJgjqzvO1vFffRWRi5WImJ8plH7A2ZeG7toGMukz3gK0Ci5n 17Sw== X-Gm-Message-State: AAQBX9cQhfN6arxMfuUa+/WR6Exvz1GAxhN5D/lWPKv3WMmRyySvgZrK Sp5QqDf1JA9hPAQlP1N5T4s= X-Google-Smtp-Source: AKy350aK6md8FixFJDpdapTWrHtnA37QUe/679Rdn27v3JS7Plt90DWk4XdnrJDa7u/grBOVmiDaeg== X-Received: by 2002:a17:902:c401:b0:1a1:b9e6:2896 with SMTP id k1-20020a170902c40100b001a1b9e62896mr42079049plk.45.1680349116938; Sat, 01 Apr 2023 04:38:36 -0700 (PDT) Received: from [192.168.0.110] ([114.29.91.56]) by smtp.gmail.com with ESMTPSA id o21-20020a170903211500b001a25fe38789sm3208959ple.60.2023.04.01.04.38.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 01 Apr 2023 04:38:36 -0700 (PDT) Message-ID: <51b8ae95-da5f-f426-feef-ff10c8c3e583@gmail.com> Date: Sat, 1 Apr 2023 20:38:39 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH] mm: remove all the slab allocators Content-Language: en-US To: Vlastimil Babka , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, patches@lists.linux.dev References: <20230401094658.11146-1-vbabka@suse.cz> From: Vlastimil Babka <42.hyeyoo@gmail.com> In-Reply-To: <20230401094658.11146-1-vbabka@suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 219A22000B X-Stat-Signature: yptg38snqs8fo379xssn4phdkfztmg75 X-HE-Tag: 1680349117-976955 X-HE-Meta: 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 bEhe989b 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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: On 4/1/2023 6:46 PM, Vlastimil Babka wrote: > As the SLOB removal is on track and the SLAB removal is planned, I have > realized - why should we stop there and not remove also SLUB? What's a > slab allocator good for in 2023? The RAM sizes are getting larger and > the modules cheaper [1]. The object constructor trick was perhaps > interesting in 1994, but not with contemporary CPUs. So all the slab > allocator does today is just adding an unnecessary layer of complexity > over the page allocator. Oh my goodness, I am on vacation now and looks like someone is pretending to be me. Probably my account was hacked. Please ignore this whole thread. > Thus, with this patch, all three slab allocators are removed, and only a > layer that passes everything to the page allocator remains in the slab.h > and mm/slab_common.c files. This will allow users to gradually > transition away and use the page allocator directly. To summarize the > advantages: > > - Less code to maintain: over 13k lines are removed by this patch, and > more could be removed if I wast^Wspent more time on this, and later as > users are transitioned from the legacy layer. This no longer needs a > separate subsystem so remove it from MAINTAINERS (I hope I can keep the > kernel.org account anyway, though). > > - Simplified MEMCG_KMEM accounting: while I was lazy and just marked it > BROKEN in this patch, it should be trivial to use the page memcg > accounting now that we use the page allocator. The per-object > accounting went through several iterations in the past and was always > complex and added overhead. Page accounting is much simpler by > comparison. > > - Simplified KASAN and friends: also was lazy in this patch so they > can't be enabled but should be easy to fix up and work just on the > page level. > > - Simpler debugging: just use debug_pagealloc=on, no need to look up the > exact syntax of the absurdly complex slub_debug parameter. > > - Speed: didn't measure, but for the page allocator we have pcplists, so > it should scale just fine. No need for the crazy SLUB's cmpxchg_double() > craziness. Maybe that thing could be now removed too? Yeah I can see > just two remaining users. > > Any downsides? Let's look at memory usage after virtme boot: > > Before (with SLUB): > Slab: 26304 kB > > After: > Slab: 295592 kB > > Well, that's not so bad, see [1]. > > [1] https://www.theregister.com/2023/03/29/dram_prices_crash/ > --- > MAINTAINERS | 15 - > include/linux/slab.h | 211 +- > include/linux/slab_def.h | 124 - > include/linux/slub_def.h | 198 -- > init/Kconfig | 2 +- > mm/Kconfig | 134 +- > mm/Makefile | 10 - > mm/slab.c | 4046 ------------------------ > mm/slab.h | 426 --- > mm/slab_common.c | 876 ++--- > mm/slob.c | 757 ----- > mm/slub.c | 6506 -------------------------------------- > 12 files changed, 228 insertions(+), 13077 deletions(-) > delete mode 100644 include/linux/slab_def.h > delete mode 100644 include/linux/slub_def.h > delete mode 100644 mm/slab.c > delete mode 100644 mm/slob.c > delete mode 100644 mm/slub.c > diff --git a/MAINTAINERS b/MAINTAINERS > index 1dc8bd26b6cf..40b05ad03cd0 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -19183,21 +19183,6 @@ F: drivers/irqchip/irq-sl28cpld.c > F: drivers/pwm/pwm-sl28cpld.c > F: drivers/watchdog/sl28cpld_wdt.c > > -SLAB ALLOCATOR > -M: Christoph Lameter > -M: Pekka Enberg > -M: David Rientjes > -M: Joonsoo Kim > -M: Andrew Morton > -M: Vlastimil Babka > -R: Roman Gushchin > -R: Hyeonggon Yoo <42.hyeyoo@gmail.com> > -L: linux-mm@kvack.org > -S: Maintained > -T: git git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git > -F: include/linux/sl?b*.h > -F: mm/sl?b