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=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 7426EC4332B for ; Fri, 20 Mar 2020 09:17:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 445EE20781 for ; Fri, 20 Mar 2020 09:17:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="D4VZqvnk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726834AbgCTJRc (ORCPT ); Fri, 20 Mar 2020 05:17:32 -0400 Received: from mail-il1-f194.google.com ([209.85.166.194]:45770 "EHLO mail-il1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726654AbgCTJRb (ORCPT ); Fri, 20 Mar 2020 05:17:31 -0400 Received: by mail-il1-f194.google.com with SMTP id m9so4882445ilq.12 for ; Fri, 20 Mar 2020 02:17:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=s5yjE/VD/ici0HoXri9KyCxtUxAZijJK4qMSKaKWPS8=; b=D4VZqvnklKFyH0XWVVJo/Pr/kEQY5Fj4bYWa6AmSmMBB8qO/4hl6SE4YMOAtPPEKo1 FFUvZHy686eGguHMbV00hZyGhA3F3Of1AN8frsBzlKPVQcMB+B7Tukj1M2Vwp7dOU6Tx iQUg93a+jAjN+8IGpxGYVgYar2Wjf9yI2aEdVDjn1mRvrymspnsZuaD5zanbuB1K0OFC UDNlNv1Syyb+v86xBZMdZN5eu9KFImj44GCoIBFPZuVi4FuaoVU5dQqbvFdc995f+TG0 JyciDanu9Hv+NkQFZ7LtjnPx9XwYCT3luV6uYKFsfzKHYHBUqKcTIeqcshwvLb3vqRaX OuuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=s5yjE/VD/ici0HoXri9KyCxtUxAZijJK4qMSKaKWPS8=; b=FJ1i0fxPIzQhIez4U/Vr2VyXVJydnTViOmcJ08cQQCXXwiqFqhfDEynQMR0tX1+ELP FINlM1AnfS1Lm7TmJOEpv1tNie9jQPlaflKQiszqL7SRpKf2eO4kIn+0M1rQUeQKYWl2 X0lKG+2TSyXKcJD5YNtKGegTT07aP+0I+fehp63atOj2USzTqS9D3a9k0PBu9hCMRl9W 1TZgyNSJ2NNEEihZfc4gOhuz2WV7UcFr/4WyTWFvmz6lrNbIuXuqIGjZr4D6iknU+KXI /+QuYjymoCn20mV7UA1Qu6gZAzVErShQgXa7K9+OvivrZgu+068CVZIdSzvjn8cki4dp JYVw== X-Gm-Message-State: ANhLgQ1LHdR4JqdZE2CHxnlQx+nP/RHsnBk4IUoIw8al7qms1QQAClc7 /e3O0u9rSBVsD+LBO+H/HvbAp+Fj8gyUo+K4ZXWNSxo= X-Google-Smtp-Source: ADFU+vusRpBm4rNfGvTYBgBadB2eN25m8nlyvJ/Ghep4D00mRSg6qPP5/BS8BCLJSFX+OqDo3gsXeBag+fOVcLTcku8= X-Received: by 2002:a92:250e:: with SMTP id l14mr7161441ill.201.1584695850718; Fri, 20 Mar 2020 02:17:30 -0700 (PDT) MIME-Version: 1.0 References: <1584333244-10480-1-git-send-email-kernelfans@gmail.com> <1584333244-10480-4-git-send-email-kernelfans@gmail.com> <8d748bfe-b2b0-bb56-fb2c-71de86183ba5@nvidia.com> In-Reply-To: <8d748bfe-b2b0-bb56-fb2c-71de86183ba5@nvidia.com> From: Pingfan Liu Date: Fri, 20 Mar 2020 17:17:19 +0800 Message-ID: Subject: Re: [PATCHv6 3/3] mm/gup_benchemark: add LONGTERM_BENCHMARK test in gup fast path To: John Hubbard Cc: Linux-MM , Ira Weiny , Andrew Morton , Mike Rapoport , Dan Williams , Matthew Wilcox , "Aneesh Kumar K.V" , Christoph Hellwig , Shuah Khan , Alexander Duyck , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 20, 2020 at 6:27 AM John Hubbard wrote: > > On 3/15/20 9:34 PM, Pingfan Liu wrote: > > Introduce a PIN_FAST_LONGTERM_BENCHMARK ioctl to test longterm pin in gup fast > > path. > > 1. The subject line still has "benchemark", which should be "benchmark". > > 2. What do you really want to test? More about the use case to be tested would help. > Just another sentence. I wouldn't normally ask, but in this case the implementation > is slightly scrambled, and I can't suggest how to fix it because there's no information > in the commit log as to the use case, nor the motivation. Oh, the history about [3/3] is to verify the implementation method of [2/3]. Please refer to https://lore.kernel.org/linux-mm/20190611122935.GA9919@dhcp-128-55.nay.redhat.com/ Cite " > > I think the concern is: for the successful gup_fast case with no CMA > > pages, this patch is adding another complete loop through all the > > pages. In the fast case. > > > > If the check were instead done as part of the gup_pte_range(), then > > it would be a little more efficient for that case. > > > > As for whether it's worth it, *probably* this is too small an effect to measure. > > But in order to attempt a measurement: running fio (https://github.com/axboe/fio) > > with O_DIRECT on an NVMe drive, might shed some light. Here's an fio.conf file > > that Jan Kara and Tom Talpey helped me come up with, for related testing: " But I think now, there is no motivation for it, and can be dropped it now. Thanks, Pingfan