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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44780EE49A5 for ; Tue, 22 Aug 2023 19:49:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230299AbjHVTtz (ORCPT ); Tue, 22 Aug 2023 15:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229514AbjHVTty (ORCPT ); Tue, 22 Aug 2023 15:49:54 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD4EFCCB for ; Tue, 22 Aug 2023 12:49:52 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id d2e1a72fcca58-68a3f1d8be2so2297526b3a.3 for ; Tue, 22 Aug 2023 12:49:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692733792; x=1693338592; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=poyvuz4d7dAHCrItBaYh47AoS5CadHl5LbM0lDfEjyk=; b=fMwb16nauGn/DJmL0n4N3Np/PI2YaMt8COJh2lKCnojD+7Fniop5qct73rRH8NozAQ y563nt+jmA6qf9wZbkJSRmNqd/+17t7m1ejHA9Jv+pfP+2kOli0ZttvG6yR9c7VMcvXM 15mdnHlEKbu2VxRj2lMiXGdzbAoYrpPfkKAZrOoHplqDpMSs5pThEWW5YtSvZXwlxUWv 7BB0Q/o+HjIQWY0oQ2rjOUMSCEA4pVrDKuWIISyQSx7+WQs9d2cz9RK84IHh6ME5vcSg 6yMWzBYUI45Q5CphCCbZD3Px8ItU4VaezOsb8r3JXTCHlpo3+TMruf9sLjQ6C+/JrBPl TBiA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692733792; x=1693338592; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=poyvuz4d7dAHCrItBaYh47AoS5CadHl5LbM0lDfEjyk=; b=afp80KmNt1Hb1Za1RiRbxH01QOYQ17Ftg6l5PENZdlS0WzwhJPHzSeFsK+xBfK185K 9hoI3VmFTA14aSnkrbAh4JTSSK38527BmwJYbKx+LAwEFPAjyNcCUFc8PBzMxAGG3aZk ATPnLtFj2GqCnnqgs4qSd2FtOtLoGbT3zNiX8H/PC+3qBiKYanPn+GXzIIssrvKCvlr2 P2OnhuUbb2j5boVHk5661v6OkImb7Y6r1hoVjhtk335tynhY9gUGmQpPPcbetDmHQdHk 6fRQxNruQc+5GkaOr3m85CCGEVwDJy3PHWcxREX9nWxrLe3KaMLEBv98mzxRVDK/Wl1J oM3g== X-Gm-Message-State: AOJu0YwLIkdNZ02JqgJGUke6mf2mbSZLGfYHG92AtiYsvvXNc+twi+s2 m+AOlDmaETjrtAiD0K1jICXyrb8Fua0= X-Google-Smtp-Source: AGHT+IEItHCrIzWdBGFHJB4RoCk2XPY8yU0d8ykVbgPXPcaOyBZISzgSI1SsVorKp3y2XKQSBdOUog== X-Received: by 2002:a05:6a20:5489:b0:148:479a:eb7 with SMTP id i9-20020a056a20548900b00148479a0eb7mr14603099pzk.61.1692733792172; Tue, 22 Aug 2023 12:49:52 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:8fa0]) by smtp.gmail.com with ESMTPSA id z7-20020a633307000000b005642314f05fsm8304091pgz.1.2023.08.22.12.49.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Aug 2023 12:49:51 -0700 (PDT) Sender: Tejun Heo Date: Tue, 22 Aug 2023 09:49:49 -1000 From: Tejun Heo To: Tio Zhang Cc: linux-kernel@vger.kernel.org, jiangshanlai@gmail.com, zyhtheonly@gmail.com, zyhtheonly@yeah.net Subject: Re: [PATCH v2] workqueue: let WORKER_CPU_INTENSIVE be included in watchdog Message-ID: References: <202308142140.cf9be57a-oliver.sang@intel.com> <20230822110609.GA3702@didi-ThinkCentre-M930t-N000> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230822110609.GA3702@didi-ThinkCentre-M930t-N000> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 22, 2023 at 07:06:51PM +0800, Tio Zhang wrote: > When a pool has a worker with WORKER_CPU_INTENSIVE set but other workers > are not that busy, the pool->worklist will mostly be empty, which leads > the intensive work always having a chance of escaping from the watchdog's > check. This may cause watchdog miss finding out a forever running work > in WQ_CPU_INTENSIVE. > > Also, after commit '616db8779b1e3f93075df691432cccc5ef3c3ba0', > workers with potentially intensive works will automatically be converted > into WORKER_CPU_INTENSIVE. This might let watchdog to miss all work > potentially running forever. The watchdog is there to ensure forward progress. CPU_INTENSIVE work items don't block other work items, so I'm not sure why it should trigger the watchdog. Thanks. -- tejun