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 AC828C83F15 for ; Wed, 30 Aug 2023 19:30:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241884AbjH3Tak (ORCPT ); Wed, 30 Aug 2023 15:30:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343984AbjH3RvT (ORCPT ); Wed, 30 Aug 2023 13:51:19 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7ABA3193 for ; Wed, 30 Aug 2023 10:51:16 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id 98e67ed59e1d1-27183f4ccc1so6287a91.2 for ; Wed, 30 Aug 2023 10:51:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1693417876; x=1694022676; darn=vger.kernel.org; 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=mWxHZBHe+McomQO2YHa9mxYrBp2VqVWidmsS0Hpwi+s=; b=SN/zYNMbx+ezV1EayCdP8voonBBDg6SwlypnEjXKu8qrYWhWlTOBZkWc1VHh8qa+lJ rz0iwG4TlPbBvMFHveEiUlbKWIKAl0Z/hnKSjoE4YydXYZnHY/bdcrDinQ1+iWC3pYQf Fq1TikPEVnG8AS4e/vHOb/Wp+XvtPIfTC6lUZpFSf1HecZ7wiIxmKdOt0pL5AQ09appS tsoDK8nNvdkYZu6bg+YA7UwmKOZYFuhbve0+rGVOtLdZCPxTJilDsCCAgv2xW9IAXVEz hm4EYrLnp0rcjPTzceiugYyY5E8b++NmTPmSMFaGRhZsE2FaTLFsehtMPeDOidNN11AO p0Ig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693417876; x=1694022676; 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=mWxHZBHe+McomQO2YHa9mxYrBp2VqVWidmsS0Hpwi+s=; b=CEgC8PgPvJ70BKe8AtrUJGhXEaq/vs7JJ6EUwMb0msjPRcV1PCSF+0d568/XxUvDWs igvPVpJX8sF7wcBaSJj3HUP2QYm38H0HrHOnlNg82AkQNXc6afijbCB9xBWMiSsX82p5 lMicyJLN3bfg2GCMaKEuC08CI5Rvi4eXltccCDIoyJEbUmdo5wg1kMI2LDUZl8igUS7Q rx+eSr/iSmh5xvqYlJT1qZVZIcHK3Ex9qX60MF/m9LBcaoYH/em9GzesCrSFVu/OOIOd LHBnRalBGKj/JeIfoTuiZ++3EAWBXsHC1gM7XXLVOycf2L4MulIi9LfuDxBdL/7bSxe1 uhTA== X-Gm-Message-State: AOJu0YwUZlG2fTuDTFxYh2GVlfmrbZXQIQuMVp0RYu7tzyaWGS/iOLhs 05fsuibPFjXfC3D3Z+fr3Qbme0vGPR0= X-Google-Smtp-Source: AGHT+IFOnDLb75qnIk8shTUqbVkDhI7QMBhXtBxk+doHCAIlVlzWjbe70pnsbZITl3aGZjTkxhiRNA== X-Received: by 2002:a17:90b:196:b0:268:81c6:a01f with SMTP id t22-20020a17090b019600b0026881c6a01fmr2926973pjs.26.1693417875803; Wed, 30 Aug 2023 10:51:15 -0700 (PDT) Received: from localhost (dhcp-72-235-13-41.hawaiiantel.net. [72.235.13.41]) by smtp.gmail.com with ESMTPSA id nh5-20020a17090b364500b0026b0b4ed7b1sm1525450pjb.15.2023.08.30.10.51.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 10:51:15 -0700 (PDT) Sender: Tejun Heo Date: Wed, 30 Aug 2023 07:51:13 -1000 From: Tejun Heo To: Heiner Kallweit Cc: Linux Kernel Mailing List , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , intel-gfx@lists.freedesktop.org Subject: Re: WQ_UNBOUND warning since recent workqueue refactoring Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, (cc'ing i915 folks) On Wed, Aug 30, 2023 at 04:57:42PM +0200, Heiner Kallweit wrote: > Recently I started to see the following warning on linux-next and presumably > this may be related to the refactoring of the workqueue core code. > > [ 56.900223] workqueue: output_poll_execute [drm_kms_helper] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND > [ 56.923226] workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND > [ 97.860430] workqueue: output_poll_execute [drm_kms_helper] hogged CPU for >10000us 8 times, consider switching to WQ_UNBOUND > [ 97.884453] workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 8 times, consider switching to WQ_UNBOUND > > Adding WQ_UNBOUND to these queues didn't change the behavior. That should have made them go away as the code path isn't active at all for WQ_UNBOUND workqueues. Can you please double check? > Maybe relevant: I run the affected system headless. i915 folks, workqueue recently added debug warnings which trigger when a per-cpu work item hogs the CPU for too long - 10ms in this case. This is problematic because such work item can stall other per-cpu work items. * Is it expected for the above two work functions to occupy the CPU for over 10ms repeatedly? * If so, can we make them use an unbound workqueue instead? Thanks. -- tejun