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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E4D7C4332F for ; Sat, 12 Nov 2022 01:41:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233502AbiKLBlG (ORCPT ); Fri, 11 Nov 2022 20:41:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229991AbiKLBlD (ORCPT ); Fri, 11 Nov 2022 20:41:03 -0500 Received: from esa5.hgst.iphmx.com (esa5.hgst.iphmx.com [216.71.153.144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDEE56584D for ; Fri, 11 Nov 2022 17:41:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1668217261; x=1699753261; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=kWfbDk7epBE8N+lvIUYGuQa6NGCEfO5LUkxzV91Rv/U=; b=VNBarMPfMfkH6qP8EH8oZTd3xvghcFcwIAMKcBYPAnRxCP2FU79OGPPM Schnnnv20PsVTBkuqmIjYPTov31s2GyP2yC6G6ulxX+T88bVwLGl/NJAa f5/SlCNIfCFKoJNLSz/jgzR/YX7jE9Jvs8+Ao2M4s3TmI9mpkH9RzHvee 7btveWUmWGBJLGJJBKBF8hxES/OgjoxDXoiaWGjqyDnXOKB2FmlnrU7Uw MofXlTrIjuglqZYbyEstRcLZ+jpqcGSYHfVCQ4k3qIItVOhPM0KV+xQuE 8tTBh8j0UQhd4hwP0so2DA0xeiEcvs/BalwefVLRADANuGWb/hiErq5GD A==; X-IronPort-AV: E=Sophos;i="5.96,158,1665417600"; d="scan'208";a="216094310" Received: from h199-255-45-15.hgst.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 12 Nov 2022 09:41:01 +0800 IronPort-SDR: lDNfaju6bV9TDpTB/6Pj4bpZ3DIWSLQg+z2qaS1DNwmGDZAQJmYJ1PC8jfhgH91/+dGl/q74VH yA4+Dp1/aCscLb8RZkx2jdkNHLLriLhvLJGBIRRmL8k/HqAYJmABomOegNt0pCcknWzIBJMwOt 9bpkPFoXhKA6WBFuwpuWlapX6zVgcmJi7nhnVEbM72kXfnMJvfq7ezVTS38aEicQgEc57iOCjB sBPe5yA3NwwEAhAshDzqH3Mj0AV3igXL+4qDJKXEwusaB9iW7NVAOrzODY8hA+7nAwjMjf01V9 u0s= Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 11 Nov 2022 16:54:17 -0800 IronPort-SDR: orSYoWCeCVHYUBbwJhYbX85iejdZ47IpiUzWIm2DBSU0ltyymYO9F1/eiZt0lbGjBgzy7ba1i9 NWYmS1pv3VSTeygtMGADBBDSxgxC55xLHwKzkZiN50e09charD4sR7pBQqB6msv9THPv6i908c gN3T00KIQCipgarlMZJ1Enw6zMLaXEH/tnSDyhJrGcWSyhW862juDK+5RgAzoRe9NKhkIVSHNX lISxBiQQXKbSy/P1IpLTJTsUDN6naOWT9VxZA3YYHfTt+jlyu3asBbe7MRpPxMr3hjRtU0pwbV zw4= WDCIronportException: Internal Received: from usg-ed-osssrv.wdc.com ([10.3.10.180]) by uls-op-cesaip02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 11 Nov 2022 17:41:01 -0800 Received: from usg-ed-osssrv.wdc.com (usg-ed-osssrv.wdc.com [127.0.0.1]) by usg-ed-osssrv.wdc.com (Postfix) with ESMTP id 4N8JF869d3z1RwtC for ; Fri, 11 Nov 2022 17:41:00 -0800 (PST) Authentication-Results: usg-ed-osssrv.wdc.com (amavisd-new); dkim=pass reason="pass (just generated, assumed good)" header.d=opensource.wdc.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d= opensource.wdc.com; h=content-transfer-encoding:content-type :in-reply-to:organization:from:references:to:content-language :subject:user-agent:mime-version:date:message-id; s=dkim; t= 1668217259; x=1670809260; bh=kWfbDk7epBE8N+lvIUYGuQa6NGCEfO5LUkx zV91Rv/U=; b=Xt/iwKvzhSDgTK+B4NYDMAfHOtqp1/lm6m42MJplgxGQ/MhvZcg DiL5QupgB6hf9pSwls6trrK2Go0lAWor98lJ4CXB77UDfuOK8rMfb22YZtw3Pweh pFj4HQ927gmUPDBO38wl7Ip+uoDPouRj5UdJclRCe++QlSW4WcwEB3zS5c8/17Ya YhnZhArolHjrAo5SLDsgoQhohh2WglL66ga54503AkORVEj09pZexQratT96uFEg DOJmCaIsPpNzz8oZtvgW5YPUcKo1AebpsvfRu1TW7iW9MlkGGHlIGrFDC6Iq1pLS oVQLQj32vK2wFWj3Sp1cTHoo024dHRz3qSA== X-Virus-Scanned: amavisd-new at usg-ed-osssrv.wdc.com Received: from usg-ed-osssrv.wdc.com ([127.0.0.1]) by usg-ed-osssrv.wdc.com (usg-ed-osssrv.wdc.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id gKGJAEuw1Kn6 for ; Fri, 11 Nov 2022 17:40:59 -0800 (PST) Received: from [10.225.163.43] (unknown [10.225.163.43]) by usg-ed-osssrv.wdc.com (Postfix) with ESMTPSA id 4N8JF265dcz1RvLy; Fri, 11 Nov 2022 17:40:54 -0800 (PST) Message-ID: Date: Sat, 12 Nov 2022 10:40:53 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: Deprecating and removing SLOB Content-Language: en-US To: Conor Dooley , Vlastimil Babka Cc: Pasha Tatashin , Christoph Lameter , David Rientjes , Joonsoo Kim , Pekka Enberg , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Matthew Wilcox , Roman Gushchin , Linus Torvalds , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Catalin Marinas , Rustam Kovhaev , Andrew Morton , Josh Triplett , Arnd Bergmann , Russell King , Alexander Shiyan , Aaro Koskinen , Janusz Krzysztofik , Tony Lindgren , Yoshinori Sato , Rich Felker , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "linux-arm-kernel@lists.infradead.org" , openrisc@lists.librecores.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, Geert Uytterhoeven , Conor.Dooley@microchip.com, Paul Cercueil References: From: Damien Le Moal Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/12/22 05:46, Conor Dooley wrote: > On Fri, Nov 11, 2022 at 11:33:30AM +0100, Vlastimil Babka wrote: >> On 11/8/22 22:44, Pasha Tatashin wrote: >>> On Tue, Nov 8, 2022 at 10:55 AM Vlastimil Babka wrote: >>>> >>>> Hi, >>>> >>>> as we all know, we currently have three slab allocators. As we discussed >>>> at LPC [1], it is my hope that one of these allocators has a future, and >>>> two of them do not. >>>> >>>> The unsurprising reasons include code maintenance burden, other features >>>> compatible with only a subset of allocators (or more effort spent on the >>>> features), blocking API improvements (more on that below), and my >>>> inability to pronounce SLAB and SLUB in a properly distinguishable way, >>>> without resorting to spelling out the letters. >>>> >>>> I think (but may be proven wrong) that SLOB is the easier target of the >>>> two to be removed, so I'd like to focus on it first. >>>> >>>> I believe SLOB can be removed because: >>>> >>>> - AFAIK nobody really uses it? It strives for minimal memory footprint >>>> by putting all objects together, which has its CPU performance costs >>>> (locking, lack of percpu caching, searching for free space...). I'm not >>>> aware of any "tiny linux" deployment that opts for this. For example, >>>> OpenWRT seems to use SLUB and the devices these days have e.g. 128MB >>>> RAM, not up to 16 MB anymore. I've heard anecdotes that the performance >>>> SLOB impact is too much for those who tried. Googling for >>>> "CONFIG_SLOB=y" yielded nothing useful. >>> >>> I am all for removing SLOB. >>> >>> There are some devices with configs where SLOB is enabled by default. >>> Perhaps, the owners/maintainers of those devices/configs should be >>> included into this thread: >>> >>> tatashin@soleen:~/x/linux$ git grep SLOB=y > >>> arch/riscv/configs/nommu_k210_defconfig:CONFIG_SLOB=y >>> arch/riscv/configs/nommu_k210_sdcard_defconfig:CONFIG_SLOB=y >>> arch/riscv/configs/nommu_virt_defconfig:CONFIG_SLOB=y > >> >> Turns out that since SLOB depends on EXPERT, many of those lack it so >> running make defconfig ends up with SLUB anyway, unless I miss something. >> Only a subset has both SLOB and EXPERT: >> >>> git grep CONFIG_EXPERT `git grep -l "CONFIG_SLOB=y"` > >> arch/riscv/configs/nommu_virt_defconfig:CONFIG_EXPERT=y > > I suppose there's not really a concern with the virt defconfig, but I > did check the output of `make nommu_k210_defconfig" and despite not > having expert it seems to end up CONFIG_SLOB=y in the generated .config. > > I do have a board with a k210 so I checked with s/SLOB/SLUB and it still > boots etc, but I have no workloads or w/e to run on it. I will try with SLUB over the weekend. -- Damien Le Moal Western Digital Research