Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads

From: Peter Zijlstra
Date: Wed Jun 10 2015 - 05:07:47 EST


On Mon, Jun 08, 2015 at 01:48:10PM -0400, Steven Rostedt wrote:
> > commit 80ed87c8a9ca0cad7ca66cf3bbdfb17559a66dcf
> > Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > 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.
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