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 C1C3BC11F65 for ; Wed, 30 Jun 2021 22:10:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACD816147E for ; Wed, 30 Jun 2021 22:10:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232836AbhF3WNI (ORCPT ); Wed, 30 Jun 2021 18:13:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232459AbhF3WNH (ORCPT ); Wed, 30 Jun 2021 18:13:07 -0400 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D509EC061756 for ; Wed, 30 Jun 2021 15:10:36 -0700 (PDT) Received: by mail-wm1-x32c.google.com with SMTP id a5-20020a7bc1c50000b02901e3bbe0939bso2705966wmj.0 for ; Wed, 30 Jun 2021 15:10:36 -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=zD2IGUHYtBe4hIYMZij30vVwJWchrWWuYMxaHm311E4=; b=rXIRp84Fr6yDmB2FNQe8VfC2JaApxzH3wIrWhuC+6LuebtsgDfOYWkCd66teG3tV3v XCJUOMmUCgTlfOJfJoU1QW8uYCVvdfEThj55E2ncFLdxJp7PzZDSMgv4mMA3i9M2APPo 48yNUjb3XlsZDSGLCvKugsPkdMuJByWOB9/Yc+VCgl2P4bYw5IG4hAp6eWU/GerMxSVY xq3FZgFzZ76kXW1rpm5jWR8FyKm7r25EpqLz9TLWU0u/46kAYWAaQwUFAmFRkUCXK2Zt aBBEgXjDVsCnfF4ENj0iKNnWa7/GRevKUt6tA0W/BwQsTXfblIgoziFUZYK4ffNYYqbl V3dw== 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=zD2IGUHYtBe4hIYMZij30vVwJWchrWWuYMxaHm311E4=; b=JZmXTK8S80N5MHYbl3bE/YRRZuXpxSKbuYAgqkX48EtE+oNfLRz4uyaaoyRMH1nH0z O7PlX/1y02udG3NpZt/WiEh1A8Pe5pTXtsrEXe7LKpvXodJ/MoQjA7Kfqwum3/TNKvVJ Nwgze7iH2bmrx3lPVhrPOHcfZJpfK7cRMCvdFwxZRmjl9YV7/JenVKAr/H5rpl9JOJN2 pVLUdLDEDWA6i5njLoBr5SYptYYB5DzC9Q9L0Qf/jvXEn2BQfoEK0YamImB9gKW4Lk1R AEvtbwB9/T0+sOjiybA9+rUFBV0MOIEIzMulgfIRxupPQhcR0Orj7ze0z75ej9AyLFlV 5UhA== X-Gm-Message-State: AOAM533NZyxh/xuo3aalV/sQ/zQ57gsOl9lniPR7BqxWRX5Ns0IHCUt0 YIQrjvAMnFgnibIgPg53tXNygjcLphImKSy5 X-Google-Smtp-Source: ABdhPJwbxOl3rpCdDUA4YzRytnh/fz64xb5wm94klbLBU1+Z1JJB8cf6tmnV+G3OobB3RYHek6vIXw== X-Received: by 2002:a7b:c0c5:: with SMTP id s5mr15313460wmh.173.1625091035358; Wed, 30 Jun 2021 15:10:35 -0700 (PDT) Received: from [192.168.8.197] ([85.255.233.185]) by smtp.gmail.com with ESMTPSA id w9sm4404048wmc.19.2021.06.30.15.10.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Jun 2021 15:10:35 -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 23:10:18 +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 10:56 PM, Jens Axboe wrote: > On 6/30/21 3:45 PM, Jens Axboe wrote: >> On 6/30/21 3:38 PM, Pavel Begunkov wrote: >>> 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. >> >> Right, I was thinking it was related to the swapping of the signal >> exit and task work run ordering. But didn't look that far yet... > > BTW, in usual testing, even just the one hunk removing the exit check > seems to result in quite a lot of memory leaks running > test/poll-mshot-update. So something is funky with the patch. I guess you're positive that patches 1-2 have nothing to do with that. Right? -- Pavel Begunkov