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c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=6o0JaodUdCinHCuijBKMPPDh4qNhM3W4CwZTMs5pShU=; b=7vNIWyFESIlD0oPAkje/rTLGx59pby4FhWjrpxLcSNkAtsacD0rQjEtzar23ZHDpwm r3+D7ug2YL5W+b866VjKrs+g+ZududW/FhqwPFq4oGurW3aFEAOP9ilbfPiaxBQ94NEY MF85pCMqPl76VU6jisJjdJren6DuQZuX87wMVwFqcTLKw5EP8dAdZChOIPiSHC7UIJQh 1XDeyPfHN9RrseH5PDWDB8Ddr8Xdw04rkJ5lvw+7a8oLyRhK2d9l8UvCLsvQtNQL7AJ7 vYrhVPJaGMfDXLgJUJeBt5ryXyKjEgPb1N8i1iD0gw+Q5jegR5Q40UjLb9Z49NgDCyD+ VQdQ== X-Gm-Message-State: ACrzQf0qQi8iye29PZwnlJeV59p3tDRHw7ByRmEyf1MKJLbrnsRI60FP ueK1I49/TFtwh3iazebT1R3hdzhmX451GcrRJck= X-Google-Smtp-Source: AMsMyM5vTjPHFhQ2vYKc1ap+Gnz9Xnoi5f6pFtOuhyEULsih6osIQH75MdocdJksgvBY7Bht8TwzxWn0ElldlUKBtUU= X-Received: by 2002:a17:902:da82:b0:186:ee5a:47c7 with SMTP id j2-20020a170902da8200b00186ee5a47c7mr63072929plx.82.1668028625070; Wed, 09 Nov 2022 13:17:05 -0800 (PST) MIME-Version: 1.0 References: <87187c52-ae48-130b-6479-ae1023915bc1@suse.cz> <20221109155008.GC307514@darkstar.musicnaut.iki.fi> In-Reply-To: <20221109155008.GC307514@darkstar.musicnaut.iki.fi> From: Janusz Krzysztofik Date: Wed, 9 Nov 2022 22:16:53 +0100 Message-ID: Subject: Re: Deprecating and removing SLOB To: Vlastimil Babka , Aaro Koskinen 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 , 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 Content-Type: text/plain; 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dkim=pass header.d=gmail.com header.s=20210112 header.b=b7JdsqL9; spf=pass (imf12.hostedemail.com: domain of jmkrzyszt@gmail.com designates 209.85.216.48 as permitted sender) smtp.mailfrom=jmkrzyszt@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: o9apmau9uzqoxitgdztbcbcjhjttz18c X-HE-Tag: 1668028626-439205 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 Wednesday, 9 November 2022 16:50:08 CET 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. > > There are OMAP1 boards with only 16 MB, but support for those boards > will be removed. So from OMAP1 side, I don't think there is any real > need for SLOB anymore. Moreover, I always had issues with availability of socket buffers during USB device setup when trying to use SLOB on Amstrad Delta based on OMAP1510, the least powerful OMAP1. Then, +1 for SLOB removal. Thanks, Janusz