From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads Date: Wed, 10 Jun 2015 11:07:24 +0200 Message-ID: <20150610090724.GD3644@twins.programming.kicks-ass.net> References: <1433516477-5153-1-git-send-email-pmladek@suse.cz> <1433516477-5153-10-git-send-email-pmladek@suse.cz> <20150605161021.GJ19282@twins.programming.kicks-ass.net> <20150608134810.3abd862b@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150608134810.3abd862b-f9ZlEuEWxVcJvu8Pb33WZ0EMvNT87kid@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Steven Rostedt Cc: Petr Mladek , Andrew Morton , Oleg Nesterov , Tejun Heo , Ingo Molnar , Richard Weinberger , David Woodhouse , linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Trond Myklebust , Anna Schumaker , linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Chris Mason , "Paul E. McKenney" , Thomas Gleixner , Linus Torvalds , Jiri Kosina , Borislav Petkov , Michal Hocko , live-patching-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Mon, Jun 08, 2015 at 01:48:10PM -0400, Steven Rostedt wrote: > > commit 80ed87c8a9ca0cad7ca66cf3bbdfb17559a66dcf > > Author: Peter Zijlstra > > Date: Fri May 8 14:23:45 2015 +0200 > > > > sched/wait: Introduce TASK_NOLOAD and TASK_IDLE > > > > Currently people use TASK_INTERRUPTIBLE to idle kthreads and wait for > > 'work' because TASK_UNINTERRUPTIBLE contributes to the loadavg. Having > > all idle kthreads contribute to the loadavg is somewhat silly. > > Not to mention, tasks in TASK_UNINTERRUPTIBLE state for too long will > trigger hung task detection. Right, and I had not considered that, but it turns out the hung_task detector checks p->state == TASK_UNINTERRUPTIBLE, so TASK_IDLE is indeed safe from that. From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 10 Jun 2015 11:07:24 +0200 From: Peter Zijlstra To: Steven Rostedt Subject: Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads Message-ID: <20150610090724.GD3644@twins.programming.kicks-ass.net> References: <1433516477-5153-1-git-send-email-pmladek@suse.cz> <1433516477-5153-10-git-send-email-pmladek@suse.cz> <20150605161021.GJ19282@twins.programming.kicks-ass.net> <20150608134810.3abd862b@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150608134810.3abd862b@gandalf.local.home> Cc: linux-nfs@vger.kernel.org, Borislav Petkov , Thomas Gleixner , Jiri Kosina , Richard Weinberger , Trond Myklebust , Oleg Nesterov , Petr Mladek , linux-kernel@vger.kernel.org, Michal Hocko , Chris Mason , Ingo Molnar , linux-mtd@lists.infradead.org, linux-api@vger.kernel.org, Linus Torvalds , Tejun Heo , live-patching@vger.kernel.org, Andrew Morton , "Paul E. McKenney" , David Woodhouse , Anna Schumaker List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Jun 08, 2015 at 01:48:10PM -0400, Steven Rostedt wrote: > > commit 80ed87c8a9ca0cad7ca66cf3bbdfb17559a66dcf > > Author: Peter Zijlstra > > Date: Fri May 8 14:23:45 2015 +0200 > > > > sched/wait: Introduce TASK_NOLOAD and TASK_IDLE > > > > Currently people use TASK_INTERRUPTIBLE to idle kthreads and wait for > > 'work' because TASK_UNINTERRUPTIBLE contributes to the loadavg. Having > > all idle kthreads contribute to the loadavg is somewhat silly. > > Not to mention, tasks in TASK_UNINTERRUPTIBLE state for too long will > trigger hung task detection. Right, and I had not considered that, but it turns out the hung_task detector checks p->state == TASK_UNINTERRUPTIBLE, so TASK_IDLE is indeed safe from that. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from casper.infradead.org ([85.118.1.10]:57602 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752109AbbFJJHi (ORCPT ); Wed, 10 Jun 2015 05:07:38 -0400 Date: Wed, 10 Jun 2015 11:07:24 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: Petr Mladek , Andrew Morton , Oleg Nesterov , Tejun Heo , Ingo Molnar , Richard Weinberger , David Woodhouse , linux-mtd@lists.infradead.org, Trond Myklebust , Anna Schumaker , linux-nfs@vger.kernel.org, Chris Mason , "Paul E. McKenney" , Thomas Gleixner , Linus Torvalds , Jiri Kosina , Borislav Petkov , Michal Hocko , live-patching@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads Message-ID: <20150610090724.GD3644@twins.programming.kicks-ass.net> References: <1433516477-5153-1-git-send-email-pmladek@suse.cz> <1433516477-5153-10-git-send-email-pmladek@suse.cz> <20150605161021.GJ19282@twins.programming.kicks-ass.net> <20150608134810.3abd862b@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20150608134810.3abd862b@gandalf.local.home> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Jun 08, 2015 at 01:48:10PM -0400, Steven Rostedt wrote: > > commit 80ed87c8a9ca0cad7ca66cf3bbdfb17559a66dcf > > Author: Peter Zijlstra > > Date: Fri May 8 14:23:45 2015 +0200 > > > > sched/wait: Introduce TASK_NOLOAD and TASK_IDLE > > > > Currently people use TASK_INTERRUPTIBLE to idle kthreads and wait for > > 'work' because TASK_UNINTERRUPTIBLE contributes to the loadavg. Having > > all idle kthreads contribute to the loadavg is somewhat silly. > > Not to mention, tasks in TASK_UNINTERRUPTIBLE state for too long will > trigger hung task detection. Right, and I had not considered that, but it turns out the hung_task detector checks p->state == TASK_UNINTERRUPTIBLE, so TASK_IDLE is indeed safe from that.