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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 76F53C11F65 for ; Wed, 30 Jun 2021 21:39:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4726B61474 for ; Wed, 30 Jun 2021 21:39:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231704AbhF3Vla (ORCPT ); Wed, 30 Jun 2021 17:41:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229705AbhF3Vl3 (ORCPT ); Wed, 30 Jun 2021 17:41:29 -0400 Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 307C4C061756 for ; Wed, 30 Jun 2021 14:38:59 -0700 (PDT) Received: by mail-wm1-x332.google.com with SMTP id l18-20020a1ced120000b029014c1adff1edso5425047wmh.4 for ; Wed, 30 Jun 2021 14:38:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=BhoYBYlR4YwGpZD9z6mlMPSaw63MqblQQtMK367Ndc0=; b=rHHAJatCHnMvQfPEbrkMkn2YhRaS6FqmVh8cnBSWHby0HQqhkpdV6aXT/6Mc4O3Kbd DJlvvJfEdbdZBZLKzT6pMrOY1GI8vnQMfqN7JhWseO7TEene8NGR9zW//YstLB8NnjUS d2tTN0wgs52f+OPgGEiuGa64nvGOL/YIWuo3MM8PZaZUmssc/ihuEPSLVc4cOfGwDByV MzFxjqGucJXMv49CmPe/Iw1YhVdSWS+mF6j5MgABHSIDBZ0wP2AAzOK1n+WuVAkWdfsS yl1MWpNfyN/57mDeufVoXQtD+2+vcJo81/dOYUkgLgcu4yaOnJOMZ66uO7CDYDDKyBJl 7gXg== 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=BhoYBYlR4YwGpZD9z6mlMPSaw63MqblQQtMK367Ndc0=; b=GGUkhLX0fQNZY1owZU5EdvPIrdaOfV6Lj7rCTayj6mcC9X0UocauWFCcwrJusZWo/F RUxb7SdbRK4xgH/GI47mrxw4uLogA4i5va8U5lACMO6HgU9diZ028qRr5AlVDcxf52Y2 zbQnpfKuet0WZAaRk5UfklSrr+SFtxGRYqMZUU99WqkwDkqBi68ozI/cq7MlgIJ/PuwG SnYDd1EtzPJL4tIoC7L0EtwaRxhXsqThC92C2mthpk5VI8KMLMw15vdfRNc0iBjKGAqF l43eOUBoIwi+gHxZ0G5WescZHWN3zkej95wv/l06PFX05OecYsFLLmnGcoHLfx1Lj+yZ EgFw== X-Gm-Message-State: AOAM531zqmTueqPRJquab6VNyZPhs1FOp8GCsZ8Zz2yNUPNOmbp9X9AM PvZJaJqRgBtUWLu0gZRdkfw72Zp7ecphnZbB X-Google-Smtp-Source: ABdhPJySKTN5/3aKcZ29F1UJWZH0apRJmRsil91tHR35mKUDafV9PVklhpDdw0nW5/XY7x+W6ecoJg== X-Received: by 2002:a7b:cd0d:: with SMTP id f13mr6490820wmj.89.1625089137686; Wed, 30 Jun 2021 14:38:57 -0700 (PDT) Received: from [192.168.8.197] ([85.255.233.185]) by smtp.gmail.com with ESMTPSA id c12sm22713980wrw.46.2021.06.30.14.38.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Jun 2021 14:38:56 -0700 (PDT) Subject: Re: [PATCH 3/3] io_uring: tweak io_req_task_work_add To: Jens Axboe , io-uring@vger.kernel.org References: <24b575ea075ae923992e9ce86b61e8b51629fd29.1625086418.git.asml.silence@gmail.com> <70c425a8-73dd-e15a-5a10-8ea640cdc7cd@kernel.dk> From: Pavel Begunkov Message-ID: Date: Wed, 30 Jun 2021 22:38:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 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 10:22 PM, Jens Axboe wrote: > 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 I think 1-2 is good enough for 5.14, I'll just send it for-next > just needs to be clarified a bit on why it's ok to do now. And that It should have been ok to do before those 2 patches, but haven't tracked where it lost actuality. -- Pavel Begunkov