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 E17D2C54E58 for ; Fri, 8 Mar 2024 14:58:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6011C6B0399; Fri, 8 Mar 2024 09:58:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B2096B039A; Fri, 8 Mar 2024 09:58:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 478626B039B; Fri, 8 Mar 2024 09:58:55 -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 349946B0399 for ; Fri, 8 Mar 2024 09:58:55 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id DE022A0A2B for ; Fri, 8 Mar 2024 14:58:54 +0000 (UTC) X-FDA: 81874178988.15.63B0970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf18.hostedemail.com (Postfix) with ESMTP id 45FEA1C0012 for ; Fri, 8 Mar 2024 14:58:51 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=uq7FVr3t; spf=none (imf18.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709909933; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=MRCOxp2sbv31BAbpJibpjnZDrrTgE50xZMiMFK/G0kQ=; b=7k9XlgND4plTE1i7j8h5lyoqra0pqO+5J00l52MEesVgQQU0pq0JqhcYGUfBu9xTk5Sckv NL+KgbwkJl11e2ioKezuqt4h5gsJ/scfVYITYQtsdoWreJMvHXZZhl/D3/kF/GGi80Y1iA SWUp6/2j/3Xcmyrhs007veHEycLTUJc= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=uq7FVr3t; spf=none (imf18.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709909933; a=rsa-sha256; cv=none; b=JNCN46zqSwllg149HQxnWraC1KetaZOML52bH6HiX9AC6+hvuvUrJ2QfT6U/jTf5zz+ip4 dcT4l+ihYD0mly3uRBCjYLk4PlD+aifjRVmGUwfp47cFIBKV4GVcsrwV+eCq9J/IirFysV PRqikVf52lbNVjDWhYI4mRaqQgKIL4U= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=MRCOxp2sbv31BAbpJibpjnZDrrTgE50xZMiMFK/G0kQ=; b=uq7FVr3tlUC0CtJp10+MrwU/co K1OKl00YQZ1tGtwO58yFxe0DT1yGoa9mAfaeaUkvVuN/YQMGq5DWnjJ3CsdgAb/EahsMeEWUagDAl ru4TauvuJWPIsY7+H7+wxBVmay5E4YjoP0k0Z1dSvu6meFACQoMUf5JTAaUMv6j0AMHL5gzos/MFp vqZpEYKRDaGmrPvrYNpe7uxOfEWu8gby5EJhuKPWSlat9SohMSPW8a5qC1D0/5SdHNLM54uVqrQQW jg3413KSjoEsv4OBXzW0dbWio16UZZzF0ZQyt30g27FkDymr6RX8fweQxJQkIx51yD4Iz89FHIslS zVEaQ65A==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1ribgO-0000000BiuX-3Lmm; Fri, 08 Mar 2024 14:58:48 +0000 Date: Fri, 8 Mar 2024 14:58:48 +0000 From: Matthew Wilcox To: Kent Overstreet Cc: linux-mm@kvack.org, Vlastimil Babka , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Subject: Re: [PATCH] mm/slub: Make __ksize() faster Message-ID: References: <20240308031325.218676-1-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 45FEA1C0012 X-Rspam-User: X-Stat-Signature: mskwae4dsz5ws17dwysue67ezazecijz X-Rspamd-Server: rspam01 X-HE-Tag: 1709909931-590957 X-HE-Meta: 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 rs+NOhFU eZ2Rjkk5IqpEt4bvUIfaDkOcGZX20qKOatIZ2TqocjU4ouQmMc2xp2ohXniYHXgRqek2b6DVD6eBe+SdZY0sQEJNL7of9VtqwFMcoeaItLt8hl8WyXCbdF9pDB9ZFqF3wFZetVgUoIuLHrRI8SU4JQPCXLFgVgrkXoZl/qqrhHFspXuQ1QuQkSu5UkSQgsy/IunkOxwHpAsdBNLCTBvW3Fk4ayUqEKgnbtKLvi8c5ATtCEnZkJIxFTRXTWgVnw6fbdcvK 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, Mar 08, 2024 at 12:16:09AM -0500, Kent Overstreet wrote: > On Fri, Mar 08, 2024 at 04:48:11AM +0000, Matthew Wilcox wrote: > > On Thu, Mar 07, 2024 at 10:13:22PM -0500, Kent Overstreet wrote: > > > This steals it to make __ksize() faster; it's now a single dependent > > > load, instead of two. This is going to be important for tracking the > > > amount of memory stranded by RCU, which we want to be able to do if > > > we're going to be freeing all pagecache folios (and perhaps all folios) > > > via RCU. > > > > Do you have any measurements? I don't necessarily object, it's just > > that I would have thought we were already bringing slab->slab_cache > > into cache as part of the freeing operation. > > for kfree() yes, but for kfree_rcu() no - that'll happen significantly > later. > > I don't have measurements that it /matters/, but since we have the u32 > there now this seems like a good use for it. There are potentiually better uses for those bits. We could turn folio_test_slab() into a PageType test, freeing up a page flag.