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 52178C636D3 for ; Mon, 30 Jan 2023 22:15:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231425AbjA3WPr (ORCPT ); Mon, 30 Jan 2023 17:15:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59398 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230098AbjA3WPq (ORCPT ); Mon, 30 Jan 2023 17:15:46 -0500 Received: from mail-io1-xd35.google.com (mail-io1-xd35.google.com [IPv6:2607:f8b0:4864:20::d35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D19F128D21 for ; Mon, 30 Jan 2023 14:15:44 -0800 (PST) Received: by mail-io1-xd35.google.com with SMTP id e2so2305472iot.11 for ; Mon, 30 Jan 2023 14:15:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=UpRPgXbzyPldfryxFZ4ysKITNhIghKFBROqanj/f/Sk=; b=Rimt7EyQJHAERbMyCMmnlRKfnzUd6ivIuLZcpvfDAKKf1XtrAzyKZgGyH4SsI1VCFl y71zP0cpkkZADufU3KMqa/2ZG7kemElm2dlXFsHsQwBCYQdp9/LMEKIABfWkxUUL24fs nOyHaogacUTLL2qE3KxiNjWzUgstTBfVOGGxj1ot6sSbvHczG4x2gEc06S02JBVFQqw/ Zk3AjJ6WbeoqERAzuBWIbsxeQKQs2RwDjQsb6pWpRLl6lHoMSOdPV/+Xz+yX9n9BFKuA +q6AWSjEehghz28No7wOXPpAhkJQIqEVkeiyYYwlAzeLcE2jfwoVSl+BSXAQkNUkoEnX jnmg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=UpRPgXbzyPldfryxFZ4ysKITNhIghKFBROqanj/f/Sk=; b=aaBHK4AOAL9D943wSBBhR0eQ+kgs5q8pHvetQz7jdDgocjcic9e8TGbwa2mqrt1KWz Jm+WVcHt+fi55/H8kHwhkLzBeXPEs/qFRN/UyPMbcwQZ1KfaZOBI18w9BGtuRUGMnhcL KU6CvGmcn2eIT09R4+/KBLXB4Awd1cgbfWRw5EgqLgcbypAr76mwaMIm9Ki6TkRchpo8 toryX1CDixwg7Pp5Lymj78JJ+qPikaDf3IOQGbRZFhARa6h75LmtKUlj73HyZuqHKUjd WevvbgQIvfm+h3IfSLINjFQyzsVtpUqAxrlxAjXYJ5bvybULzBDwkEV0ppA+orIPePJM yvzA== X-Gm-Message-State: AO0yUKUK0QJlfDRK93XCCACgpBofJmxUitshz4//V6xk7VfHYD8RIHnM ixGNfgAS6lx2sKaaP/GrmHx11g== X-Google-Smtp-Source: AK7set/tqTtKUOkSBhdUWbUnjfzdSsFonAnOVZ3meWLdw53puoZxOKpLq8oYEyvusW9O1BKkg3hUeQ== X-Received: by 2002:a5d:9d11:0:b0:718:2fa2:6648 with SMTP id j17-20020a5d9d11000000b007182fa26648mr1422084ioj.2.1675116944142; Mon, 30 Jan 2023 14:15:44 -0800 (PST) Received: from [192.168.1.94] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id q22-20020a5d8516000000b0071db3975335sm1082375ion.12.2023.01.30.14.15.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Jan 2023 14:15:43 -0800 (PST) Message-ID: Date: Mon, 30 Jan 2023 15:15:42 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [GIT PULL] iov_iter: Improve page extraction (pin or just list) Content-Language: en-US To: David Howells , John Hubbard Cc: Al Viro , Christoph Hellwig , Matthew Wilcox , Jan Kara , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Jeff Layton , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3351099.1675077249@warthog.procyon.org.uk> <3520518.1675116740@warthog.procyon.org.uk> From: Jens Axboe In-Reply-To: <3520518.1675116740@warthog.procyon.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 1/30/23 3:12 PM, David Howells wrote: > John Hubbard wrote: > >> This is something that we say when adding pin_user_pages_fast(), >> yes. I doubt that I can quickly find the email thread, but we >> measured it and weren't immediately able to come up with a way >> to make it faster. > > percpu counters maybe - add them up at the point of viewing? They are percpu, see my last email. But for every 108 changes (on my system), they will do two atomic_long_adds(). So not very useful for anything but low frequency modifications. -- Jens Axboe