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=-5.4 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 6C7D0C4363A for ; Fri, 23 Oct 2020 02:24:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F296D2158C for ; Fri, 23 Oct 2020 02:24:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="wpeItj4Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S374552AbgJWCYT (ORCPT ); Thu, 22 Oct 2020 22:24:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S374550AbgJWCYT (ORCPT ); Thu, 22 Oct 2020 22:24:19 -0400 Received: from mail-pg1-x535.google.com (mail-pg1-x535.google.com [IPv6:2607:f8b0:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E52DC0613CF for ; Thu, 22 Oct 2020 19:24:19 -0700 (PDT) Received: by mail-pg1-x535.google.com with SMTP id n16so2252449pgv.13 for ; Thu, 22 Oct 2020 19:24:19 -0700 (PDT) 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=IilmWqQBIzdGRFEb8WDv/BGb6Zru01TJYp2UzzvimNo=; b=wpeItj4YfzkY9NGX9eDHOZimPqRVq75UcGTuCiNxcwnlDWgOiW57hJ3NtX0tTfJp2E x2gbYpQzowr6u+7nM+r93TWzmVJxllGDoUTgZ049kEHsNpVgR0XoNyr4ckDamD/ih83h wrS82wdQoSkFPu8fwQVOA/taOU3+U89m7ITVz3gRrXAq8FpurjLUryK6+7jU8zFmVfBl bOqk86u+zEi7/njiX3F6GTKjlUlx6FUlQf1ixvdQwrqtmllqDIuFudNIsYqinCpgCbTH WlHaXTrHm+w7bpds8L3b4oGt1U2zNH03mToy3yfk3NWzqy8UBC2j6sYRhEksUGnNfc9Y uNiQ== 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=IilmWqQBIzdGRFEb8WDv/BGb6Zru01TJYp2UzzvimNo=; b=gVlkIidp1jjXpyR4YHQX5QnuCL4b+br25iK5BNL4PWH5ZdrCofQDYucyaQ2kWiuHio 22LKR7R3SyiW4OugTFoI8IWmYDg4rXgPSbTCUAMcOgNKnrSEWY2oGWo/JiY3U5ftHDnV CuNChDJsqYZBsRgCNsG/z7H/UmRLuk1EUzOZDIG77ReVVMGnJX2eMGOyAPuLGmfqjuQF y/H8jd39vpzUcGk8e43TgvntVCuqihhZhgF0cQ+XauONHKsd+9ntuj7aiGYboEZJ5Pge LCPoY4YUMzCMYjj7SjXRziEOtnHIzy/tq6Dm4ZIU5E1S0CsKPyNRB6q/LlRNsmmH3As2 wcUQ== X-Gm-Message-State: AOAM531HICS6yHnJf5BI1fP5n7UIYJtkUC9iOtmGmS4gL9wKE43Q6BQz MQg4PH49/tttjz34wIXaYj5lCg== X-Google-Smtp-Source: ABdhPJzA5EZBSeUdXLjtYYke6gTJ/cVfed1VsTekaPVYNDWK1FLHOCtzWYTzE2/HpeO13h227ZcwHA== X-Received: by 2002:a62:a10a:0:b029:154:fd62:ba90 with SMTP id b10-20020a62a10a0000b0290154fd62ba90mr10722pff.62.1603419858432; Thu, 22 Oct 2020 19:24:18 -0700 (PDT) Received: from [192.168.1.134] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id g85sm82708pfb.4.2020.10.22.19.24.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 22 Oct 2020 19:24:17 -0700 (PDT) Subject: Re: Question on io-wq To: Hillf Danton Cc: Zhang Qiang , viro@zeniv.linux.org.uk, io-uring@vger.kernel.org, Pavel Begunkov , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <98c41fba-87fe-b08d-2c8c-da404f91ef31@windriver.com> <20201023020514.2230-1-hdanton@sina.com> From: Jens Axboe Message-ID: Date: Thu, 22 Oct 2020 20:24:16 -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: <20201023020514.2230-1-hdanton@sina.com> 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 10/22/20 8:05 PM, Hillf Danton wrote: > On Thu, 22 Oct 2020 08:08:09 -0600 Jens Axboe wrote: >> On 10/22/20 3:02 AM, Zhang,Qiang wrote: >>> >>> Hi Jens Axboe >>> >>> There are some problem in 'io_wqe_worker' thread, when the >>> 'io_wqe_worker' be create and Setting the affinity of CPUs in NUMA >>> nodes, due to CPU hotplug, When the last CPU going down, the >>> 'io_wqe_worker' thread will run anywhere. when the CPU in the node goes >>> online again, we should restore their cpu bindings? >> >> Something like the below should help in ensuring affinities are >> always correct - trigger an affinity set for an online CPU event. We >> should not need to do it for offlining. Can you test it? > > CPU affinity is intact because of nothing to do on offline, and scheduler > will move the stray workers on to the correct NUMA node if any CPU goes > online, so it's a bit hard to see what is going to be tested. Test it yourself: - Boot with > 1 NUMA node - Start an io_uring, you now get 2 workers, each affinitized to a node - Now offline all CPUs in one node - Online one or more of the CPU in that same node The end result is that the worker on the node that was offlined now has a mask of the other node, plus the newly added CPU. So your last statement isn't correct, which is what the original reporter stated. -- Jens Axboe