On 10/14/2010 11:27 AM, richard -rw- weinberger wrote:
> Hi Arjan!
>
> This commit causes some problems on UML.
>
that is extremely weird.
> The kernel freezes after a few seconds until it gets some input.
> e.g: When I run top it stops refreshing the process list until i press a
> button.
a slab timer change (to not be as critical) causing global timer
issues.... that's very obviously not a problem with this patch.
has this been seem anywhere except UML ?
> Messages like this appear:
> INFO: rcu_sched_state detected stall on CPU 0 (t=7348 jiffies)
>
> After reverting UML works fine again.
>
> commit 78b435368fcd615e695a06012cd963a556284e00
> Author: Arjan van de Ven<ar...@linux.intel.com>
> Date: Mon Jul 19 10:59:42 2010 -0700
>
> slab: use deferable timers for its periodic housekeeping
>
> slab has a "once every 2 second" timer for its housekeeping.
> As the number of logical processors is growing, its more and more
> common that this 2 second timer becomes the primary wakeup source.
>
> This patch turns this housekeeping timer into a deferable timer,
> which means that the timer does not interrupt idle, but just runs
> at the next event that wakes the cpu up.
>
> The impact is that the timer likely runs a bit later, but during the
> delay no code is running so there's not all that much reason for
> a difference in housekeeping to occur because of this delay.
>
> Signed-off-by: Arjan van de Ven<ar...@linux.intel.com>
> Signed-off-by: Pekka Enberg<penb...@cs.helsinki.fi>
>
> diff --git a/mm/slab.c b/mm/slab.c
> index e49f8f4..29aad44 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -861,7 +861,7 @@ static void __cpuinit start_cpu_timer(int cpu)
> */
> if (keventd_up()&& reap_work->work.func == NULL) {
> init_reap_node(cpu);
> - INIT_DELAYED_WORK(reap_work, cache_reap);
> + INIT_DELAYED_WORK_DEFERRABLE(reap_work, cache_reap);
> schedule_delayed_work_on(cpu, reap_work,
> __round_jiffies_relative(HZ, cpu));
> }
>
>
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