Messages in this thread |  | | Date | Mon, 8 Jun 2015 13:48:10 -0400 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads |
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On Fri, 5 Jun 2015 18:10:21 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, Jun 05, 2015 at 05:01:08PM +0200, Petr Mladek wrote: > > Many kthreads go into an interruptible sleep when there is nothing > > to do. They should check if anyone did not requested the kthread > > to terminate, freeze, or park in the meantime. It is easy to do > > it a wrong way. > > INTERRUPTIBLE is the wrong state to idle in for kthreads, use > TASK_IDLE. > > --- > > commit 80ed87c8a9ca0cad7ca66cf3bbdfb17559a66dcf > Author: Peter Zijlstra <peterz@infradead.org> > 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.
> > Now mostly this works OK, because kthreads have all their signals > masked. However there's a few sites where this is causing problems and > TASK_UNINTERRUPTIBLE should be used, except for that loadavg issue. > > This patch adds TASK_NOLOAD which, when combined with > TASK_UNINTERRUPTIBLE avoids the loadavg accounting. > > As most of imagined usage sites are loops where a thread wants to > idle, waiting for work, a helper TASK_IDLE is introduced. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
-- Steve
> Cc: Julian Anastasov <ja@ssi.bg> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: NeilBrown <neilb@suse.de> > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Ingo Molnar <mingo@kernel.org> > > diff --git a/include/linux/sched.h b/include/linux/sched.h
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