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=-5.3 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,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 8B963C11F65 for ; Wed, 30 Jun 2021 21:22:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69BAE613E0 for ; Wed, 30 Jun 2021 21:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233771AbhF3VZX (ORCPT ); Wed, 30 Jun 2021 17:25:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229774AbhF3VZW (ORCPT ); Wed, 30 Jun 2021 17:25:22 -0400 Received: from mail-io1-xd2b.google.com (mail-io1-xd2b.google.com [IPv6:2607:f8b0:4864:20::d2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7A38C061756 for ; Wed, 30 Jun 2021 14:22:52 -0700 (PDT) Received: by mail-io1-xd2b.google.com with SMTP id g5so1319912iox.11 for ; Wed, 30 Jun 2021 14:22:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=iCjgPOwCo7A0wHxXgGL36eU2kMdzj5tjrrUzHkIGkko=; b=X7xYMydW7f26AUtV1zXOaC7V8x3bI77XEr+c6nkVociqRaYD6MasfP7uXGVMKRBiS7 Cb+edRICrPp0EIXh9KZLwyYxc9/R2ocJY3t7i2U9jBuZsE+r6F5jn1w2NGMdr0LV0gsF DCHDpCVfW/437nkxLxEso34XlKzxDkcv2zOMMkNYKSTdL+SuPXJc59sMJUww/So4dvYl rmr4LUHoY8j6DWye+2+WnMUDUgIhqjETsWDEpyiho4Hc9N8HlBomPb7l6KkVGAhwZpdg Gl0a5/U5KUOq2fJAO/CxmReTp/y7czbgmpgbH8xasZhV7ALTYdYKliPjrFlkxjgGLZUP ewFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=iCjgPOwCo7A0wHxXgGL36eU2kMdzj5tjrrUzHkIGkko=; b=QODnZJAWeGUtShwoYJyfA9DAlUnm3vgwsvyVRU3FZkln6ESdKx8Mt1v5tBW25q0J+c ZiNiC/+OoOjrLPVdONLYe9rCcDHANB+kgB5x6BzgvW/Pm+exSJnzDzYN5MaArgtr1qFE v9Z8FGM2z4++3LHMkQVjCN41vAICNKS+8bCdXSA7w/0A7Q9LxySZxQWDNk/jJ5Cd/99g ZxFxANGDqS8cd4hxiAN/ixyxtITS66vUKeyChMox6Eu57nRbBBNh7QTlGpOjo/S40X9Z eV+shLYxRHlMLKHy1VXxJ2v+OgpzK8yN5CkgccCnuYVBe9zv+AHfj1ObogilpHaAIe9V iDYA== X-Gm-Message-State: AOAM531lBfJUcjSfPEhFFVgUEadsTKKOklfG0QEhPbZVdqG9PxIfT1BK tKRFMqVsmtuCAsx2wKuB0BqgMhF8jdqbjQ== X-Google-Smtp-Source: ABdhPJzxKLZ6ld+xe+pS/J3i91s/lwMG7F+pHxO+g3+h3tsERKsiu3cW0taKu36x09s4fk4g1dc0UQ== X-Received: by 2002:a05:6602:2c4a:: with SMTP id x10mr5207497iov.96.1625088172135; Wed, 30 Jun 2021 14:22:52 -0700 (PDT) Received: from [192.168.1.134] ([198.8.77.61]) by smtp.gmail.com with ESMTPSA id g6sm12642184ilj.65.2021.06.30.14.22.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Jun 2021 14:22:51 -0700 (PDT) Subject: Re: [PATCH 3/3] io_uring: tweak io_req_task_work_add To: Pavel Begunkov , io-uring@vger.kernel.org References: <24b575ea075ae923992e9ce86b61e8b51629fd29.1625086418.git.asml.silence@gmail.com> <70c425a8-73dd-e15a-5a10-8ea640cdc7cd@kernel.dk> From: Jens Axboe Message-ID: Date: Wed, 30 Jun 2021 15:22:50 -0600 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: io-uring@vger.kernel.org On 6/30/21 3:19 PM, Pavel Begunkov wrote: > On 6/30/21 10:17 PM, Jens Axboe wrote: >> On 6/30/21 2:54 PM, Pavel Begunkov wrote: >>> Whenever possible we don't want to fallback a request. task_work_add() >>> will be fine if the task is exiting, so don't check for PF_EXITING, >>> there is anyway only a relatively small gap between setting the flag >>> and doing the final task_work_run(). >>> >>> Also add likely for the hot path. >> >> I'm not a huge fan of likely/unlikely, and in particular constructs like: >> >>> - if (test_bit(0, &tctx->task_state) || >>> + if (likely(test_bit(0, &tctx->task_state)) || >>> test_and_set_bit(0, &tctx->task_state)) >>> return 0; >> >> where the state is combined. In any case, it should be a separate >> change. If there's an "Also" paragraph in a patch, then that's also >> usually a good clue that that particular change should've been >> separate :-) > > Not sure what's wrong with likely above, but how about drop > this one then? Yep I did - we can do the exiting change separately, the commit message just needs to be clarified a bit on why it's ok to do now. And that last sentence dropped, of course. -- Jens Axboe