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=-5.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 CE465C4361B for ; Thu, 17 Dec 2020 19:24:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83BD3239ED for ; Thu, 17 Dec 2020 19:24:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727857AbgLQTXw (ORCPT ); Thu, 17 Dec 2020 14:23:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727260AbgLQTXw (ORCPT ); Thu, 17 Dec 2020 14:23:52 -0500 Received: from mail-il1-x12d.google.com (mail-il1-x12d.google.com [IPv6:2607:f8b0:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C185C061794 for ; Thu, 17 Dec 2020 11:23:12 -0800 (PST) Received: by mail-il1-x12d.google.com with SMTP id r17so26811380ilo.11 for ; Thu, 17 Dec 2020 11:23:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=6QrwC6GPjarKOSesNU/nFpqVImO7JnoCNayskjtahWs=; b=vMcj2+x04rTqDH5+w9XUka0PNQrNUvNtRXjgbQnT/B7cId8qsAMq3HpwHuVHNb4sfo 3B++5boZ3oiNv4SQ/eyuJQQWmwuEjVmpvDp7on8ka/GqK50QXG/NYYEzQ9Qj0XYpwwQ9 sPz+aPZKw3N/w2WnWOlAKLmErbB7yS70PxYnteZZswc7R4JgJLaANuwsxDtJaqc8bO+E Ja0QjMcnzO/mUJBi+GS4yQlqzNo7MziZLtazmcNlsRkNMcjfL43Srposwz3eD4pFAOak 9MUakiNsvQsAG+DPKFY5foNsVdlmATqRMTr/GO9Oy+rpChXUYltzF8E+JCEvb53GFyeE UbQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6QrwC6GPjarKOSesNU/nFpqVImO7JnoCNayskjtahWs=; b=PYB50EsiibbNoYgqAbqelGBqnI8h/nqXCiHkaMSn3XTPD+T6HRkuIuiPtyd0OgZQWm j+oCDQXJaDB/7ylr8sibJm2nolV6Z0a5Ms3X94hrBHNhTldchkthHSAEVdkyu36NYJB4 xIXTPMMvQCwHTjTo80Zg2+L4KHB5xgVyl8n8Ep3+BrKfsyihccK37/BfImG5CV4tvCL9 4N/tJEvuqFVZMW0kW1WJ9zaR9erMc7KepSf+xgRqI98ICUGRTsksPdlgpKUaA/Q81msY JlKtJwWiDpDKrxHYmtiKDrl53Zv1RYU6sIk4rtx6KZ2IuTHzKd0sZhge74xTAK0esLgh v4qg== X-Gm-Message-State: AOAM532UTJND+w2hO/fPjT1HruEt+h3b+Q6mkWeapZVJ+588X7d7m0lM fl20ehxsRDrCuA1M/RUb7EBrFizd7CED0w== X-Google-Smtp-Source: ABdhPJy4UsGPYepbuG7HgDZ6NkTIed0TVfmKPboxbGuN8uGeWesuA4HfMQ1/Q4BRWbUzFAW5vABh7g== X-Received: by 2002:a05:6e02:4ae:: with SMTP id e14mr359900ils.132.1608232991132; Thu, 17 Dec 2020 11:23:11 -0800 (PST) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id n77sm14947959iod.48.2020.12.17.11.23.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Dec 2020 11:23:10 -0800 (PST) Subject: Re: [PATCHSET 0/4] fs: Support for LOOKUP_CACHED / RESOLVE_CACHED To: Linus Torvalds Cc: linux-fsdevel , Al Viro References: <20201217161911.743222-1-axboe@kernel.dk> From: Jens Axboe Message-ID: <5ccf2292-01da-4ae5-c7e4-db34f824a5c9@kernel.dk> Date: Thu, 17 Dec 2020 12:23:09 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 12/17/20 11:09 AM, Linus Torvalds wrote: > On Thu, Dec 17, 2020 at 8:19 AM Jens Axboe wrote: >> [..] >> which shows a failed nonblock lookup, then punt to worker, and then we >> complete with fd == 4. This takes 65 usec in total. Re-running the same >> test case again: >> [..] >> shows the same request completing inline, also returning fd == 4. This >> takes 6 usec. > > I think this example needs to be part of the git history - either move > it into the individual commits, or we just need to make sure it > doesn't get lost as a cover letter and ends up part of the merge > message. I agree, and I think the best approach will depend a bit on whether Al takes the core bits, and then I'm left with just the io_uring part, or if the series goes in as a whole. In any case, I'll make sure it gets in as either the merge message, or (at the least) in the io_uring enablement of it. > Despite having seen the patch series so many times now, I'm still just > really impressed by how small and neat it is, considering the above > numbers, and considering just how problematic this case was > historically (ie I remember all the discussions we had about > nonblocking opens back in the days). > > So I continue to go "this is the RightWay(tm)" just from that. Well, that's largely thanks to your and Al's feedback. I did attempt this one time earlier, and the break through just wasn't there in terms of condensing it properly. I'm very happy with it now. -- Jens Axboe