lkml.org 
[lkml]   [2021]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 2/3] kfence: maximize allocation wait timeout duration
From
Date

On 2021/4/21 18:51, Marco Elver wrote:
> The allocation wait timeout was initially added because of warnings due
> to CONFIG_DETECT_HUNG_TASK=y [1]. While the 1 sec timeout is sufficient
> to resolve the warnings (given the hung task timeout must be 1 sec or
> larger) it may cause unnecessary wake-ups if the system is idle.
> [1] https://lkml.kernel.org/r/CADYN=9J0DQhizAGB0-jz4HOBBh+05kMBXb4c0cXMS7Qi5NAJiw@mail.gmail.com
>
> Fix it by computing the timeout duration in terms of the current
> sysctl_hung_task_timeout_secs value.
>
> Signed-off-by: Marco Elver <elver@google.com>
> ---
> mm/kfence/core.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index 235d726f88bc..9742649f3f88 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -20,6 +20,7 @@
> #include <linux/moduleparam.h>
> #include <linux/random.h>
> #include <linux/rcupdate.h>
> +#include <linux/sched/sysctl.h>
> #include <linux/seq_file.h>
> #include <linux/slab.h>
> #include <linux/spinlock.h>
> @@ -621,7 +622,16 @@ static void toggle_allocation_gate(struct work_struct *work)
> /* Enable static key, and await allocation to happen. */
> static_branch_enable(&kfence_allocation_key);
>
> - wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ);
> + if (sysctl_hung_task_timeout_secs) {
> + /*
> + * During low activity with no allocations we might wait a
> + * while; let's avoid the hung task warning.
> + */
> + wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate),
> + sysctl_hung_task_timeout_secs * HZ / 2);
> + } else {
> + wait_event(allocation_wait, atomic_read(&kfence_allocation_gate));
> + }
>
> /* Disable static key and reset timer. */
> static_branch_disable(&kfence_allocation_key);

\
 
 \ /
  Last update: 2021-09-16 03:03    [W:0.162 / U:0.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site