On Wed, Apr 20, 2022 at 3:46 PM Hailong Tu <tuhailong@xxxxxxxxx> wrote:
>
> The timer stays active even if the reclaim mechanism is never enabled.
> It is unnecessary overhead can be completely avoided by using module_param_call() for enabled flag.
>
> Signed-off-by: Hailong Tu <tuhailong@xxxxxxxxx>
> ---
> mm/damon/reclaim.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index e34c4d0c4d93..389c4be4f62b 100644
> --- a/mm/damon/reclaim.c
> +++ b/mm/damon/reclaim.c
> @@ -28,7 +28,6 @@
> * this.
> */
> static bool enabled __read_mostly;
> -module_param(enabled, bool, 0600);
>
> /*
> * Time threshold for cold memory regions identification in microseconds.
> @@ -358,11 +357,32 @@ static void damon_reclaim_timer_fn(struct work_struct *work)
> enabled = last_enabled;
> }
>
> - schedule_delayed_work(&damon_reclaim_timer,
> + if (enabled)
> + schedule_delayed_work(&damon_reclaim_timer,
> msecs_to_jiffies(ENABLE_CHECK_INTERVAL_MS));
> }
> static DECLARE_DELAYED_WORK(damon_reclaim_timer, damon_reclaim_timer_fn);
>
> +static int enabled_show(char *buffer, const struct kernel_param *kp)
> +{
> + return sprintf(buffer, "%c\n", enabled ? 'Y' : 'N');
> +}
> +
> +static int enabled_store(const char *val,
> + const struct kernel_param *kp)
> +{
> + int rc = param_set_bool(val, kp);
> +
> + if (rc < 0)
> + return rc;
> +
> + if (enabled)
> + schedule_delayed_work(&damon_reclaim_timer, 0);
> +
> + return 0;
> +}
> +module_param_call(enabled, enabled_store, enabled_show, &enabled, 0600);
As Matthew pointed out in the previous version, you can use
param_get_bool instead of enabled_show here.
> +
> static int damon_reclaim_after_aggregation(struct damon_ctx *c)
> {
> struct damos *s;
> --
> 2.25.1
>
