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 04FE4C43219 for ; Wed, 9 Nov 2022 17:45:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231733AbiKIRpn (ORCPT ); Wed, 9 Nov 2022 12:45:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229527AbiKIRpm (ORCPT ); Wed, 9 Nov 2022 12:45:42 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60315BA8; Wed, 9 Nov 2022 09:45:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 17E57B81F53; Wed, 9 Nov 2022 17:45:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B079DC433C1; Wed, 9 Nov 2022 17:45:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668015938; bh=i7sn7z8xD6SHJEq5dmKr3bGFRNb5IIYU4SUzL9diu3w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ARGpruzLN9OuV1JYvbeHm52w2t6ttIgcwOERaZqjZsnd7VJWeUE/iSfoj625HTPs9 LjIQy4r4/9BKNBA6nWXBmpYOA6SsvVWKXtma/QrTzMUEYdJHxRYVSM9ZzUmQDzL5gE yDkr6hT/XY5diiSADUVNUIFYs+FYy1RrzAoBCPu9+EF7pWX009Q1jSYcQpTH5/jXIz UvI5GVfMJsao2fdud1mdLsEBszy13PadoZxvIu7tt2f03u7RvYE5qrnsmDSaX9P9Yh hM2ic17YHSLgzomL7XWQE7iOvMfjj1ER/bTY5pZSY9MusLUUoQPuUHwDBgI3X4tiuz SLCO2K4jannvg== Date: Wed, 9 Nov 2022 19:45:19 +0200 From: Mike Rapoport To: Aaro Koskinen Cc: Vlastimil Babka , 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 , 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 Subject: Re: Deprecating and removing SLOB Message-ID: References: <87187c52-ae48-130b-6479-ae1023915bc1@suse.cz> <20221109155008.GC307514@darkstar.musicnaut.iki.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221109155008.GC307514@darkstar.musicnaut.iki.fi> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 09, 2022 at 05:50:08PM +0200, Aaro Koskinen wrote: > Hi, > > On Wed, Nov 09, 2022 at 10:00:25AM +0100, Vlastimil Babka wrote: > > > On Tue, Nov 8, 2022 at 10:55 AM Vlastimil Babka wrote: > > >> 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: > > [...] > > > > arch/arm/configs/omap1_defconfig:CONFIG_SLOB=y > > I have been using SLUB on my OMAP1 boards with 32 MB RAM, because of > better debugging features and the memory footprint difference doesn't > really matter for my use cases. Looking at history why SLOB was added > there, it seems it came from 6cfce27c14aa ("omap1: Add omap1_defconfig") > when separate boards configs were merged, and SX1 board happened to have > SLOB in there. This board is nowadays only used in QEMU anyway. Looks like the same happened with arch/arm/configs/pxa_defconfig. XCEP board had SLOB in its defconfig and when common pxa_defconfig was created it apparently used it. Looks like the board has 64M of RAM, so dropping CONFIG_SLOB=y from arch/arm/configs/pxa_defconfig and arch/arm/configs/xcep_defconfig seems very reasonable. -- Sincerely yours, Mike.