lkml.org 
[lkml]   [2018]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] mm, slab: reschedule cache_reap() on the same CPU
From
Date


On 11/04/2018 10.00, Vlastimil Babka wrote:
> cache_reap() is initially scheduled in start_cpu_timer() via
> schedule_delayed_work_on(). But then the next iterations are scheduled via
> schedule_delayed_work(), i.e. using WORK_CPU_UNBOUND.
>
> Thus since commit ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on
> wq_unbound_cpumask CPUs") there is no guarantee the future iterations will run
> on the originally intended cpu, although it's still preferred. I was able to
> demonstrate this with /sys/module/workqueue/parameters/debug_force_rr_cpu.
> IIUC, it may also happen due to migrating timers in nohz context. As a result,
> some cpu's would be calling cache_reap() more frequently and others never.
>
> This patch uses schedule_delayed_work_on() with the current cpu when scheduling
> the next iteration.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Fixes: ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs")
> CC: <stable@vger.kernel.org>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Stephen Boyd <sboyd@kernel.org>

Acked-by: Pekka Enberg <penberg@kernel.org>

> ---
> mm/slab.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 9095c3945425..a76006aae857 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -4074,7 +4074,8 @@ static void cache_reap(struct work_struct *w)
> next_reap_node();
> out:
> /* Set up the next iteration */
> - schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC));
> + schedule_delayed_work_on(smp_processor_id(), work,
> + round_jiffies_relative(REAPTIMEOUT_AC));
> }
>
> void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
>

\
 
 \ /
  Last update: 2018-04-11 12:53    [W:0.134 / U:0.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site