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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADD50C47255 for ; Mon, 11 May 2020 17:02:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6B1662070B for ; Mon, 11 May 2020 17:02:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="c3U4wuy0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B1662070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E98CA90006A; Mon, 11 May 2020 13:02:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E484A900036; Mon, 11 May 2020 13:02:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D84B090006A; Mon, 11 May 2020 13:02:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0028.hostedemail.com [216.40.44.28]) by kanga.kvack.org (Postfix) with ESMTP id BEE2A900036 for ; Mon, 11 May 2020 13:02:20 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 7C4738248D52 for ; Mon, 11 May 2020 17:02:20 +0000 (UTC) X-FDA: 76805056440.27.low12_4e9cf0b824555 X-HE-Tag: low12_4e9cf0b824555 X-Filterd-Recvd-Size: 3783 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 11 May 2020 17:02:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=Hy07Ws6ek9XvAGJzrptGNVmN+sgjs2KIi/oCXeVqo9E=; b=c3U4wuy0ttwAXhwRpOyq47EcOS R6BOJ5hTKfV9cW8xiSDAIUq0HXFikJF4ynwAq2vypi9olfTDqkb8ufZMT5CdzATb4pwn0Qk9J7SPT 7BH7P/aQYee+IokeeKf35kRg9Wmd7JuXGNX9J+h1igQwb86BgPLoijcEkBNddzK2nN5fn85jy8Vyt +SJyixpxAMl+sc5RquVfvSaqZYi5y8y8ukaTlE7TPPhj7mPTbxr6gjm9iNY3oHOE346HsINHrmgF9 px9am0ZSFLIKDsibuJ5+DooCPkne6W5heGMWIZYD5BJEurvKKcpF722OXItxoehCgllZpODKHto9m mF7LkNEg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYBol-0002Do-R6; Mon, 11 May 2020 17:02:16 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id DC87C304123; Mon, 11 May 2020 19:02:12 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CBF5329D8226A; Mon, 11 May 2020 19:02:12 +0200 (CEST) Date: Mon, 11 May 2020 19:02:12 +0200 From: Peter Zijlstra To: Matthew Wilcox Cc: Joerg Roedel , Joerg Roedel , x86@kernel.org, hpa@zytor.com, Dave Hansen , Andy Lutomirski , rjw@rjwysocki.net, Arnd Bergmann , Andrew Morton , Steven Rostedt , Vlastimil Babka , Michal Hocko , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings() Message-ID: <20200511170212.GI2957@hirez.programming.kicks-ass.net> References: <20200508144043.13893-1-joro@8bytes.org> <20200508192000.GB2957@hirez.programming.kicks-ass.net> <20200508213407.GT8135@suse.de> <20200509092516.GC2957@hirez.programming.kicks-ass.net> <20200510011157.GU16070@bombadil.infradead.org> <20200511073134.GD2957@hirez.programming.kicks-ass.net> <20200511155204.GW16070@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200511155204.GW16070@bombadil.infradead.org> 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 Mon, May 11, 2020 at 08:52:04AM -0700, Matthew Wilcox wrote: > On Mon, May 11, 2020 at 09:31:34AM +0200, Peter Zijlstra wrote: > > On Sat, May 09, 2020 at 06:11:57PM -0700, Matthew Wilcox wrote: > > > Iterating an XArray (whether the entire thing > > > or with marks) is RCU-safe and faster than iterating a linked list, > > > so this should solve the problem? > > > > It can hardly be faster if you want all elements -- which is I think the > > case here. We only call into this if we change an entry, and then we > > need to propagate that change to all. > > Of course it can be faster. Iterating an array is faster than iterating > a linked list because caches. While an XArray is a segmented array > (so slower than a plain array), it's plainly going to be faster than > iterating a linked list. Fair enough, mostly also because the actual work (setting a single PTE) doesn't dominate in this case.