Re: + mm-damon-reclaim-fix-the-timer-always-stays-active.patch added to -mm tree

[SeongJae Park <sj@kernel.org>]

On Thu, 21 Apr 2022 12:00:50 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> 
> The patch titled
>      Subject: mm/damon/reclaim: fix the timer always stays active
> has been added to the -mm tree.  Its filename is
>      mm-damon-reclaim-fix-the-timer-always-stays-active.patch
> 
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/mm-damon-reclaim-fix-the-timer-always-stays-active.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/mm-damon-reclaim-fix-the-timer-always-stays-active.patch
> 
> Before you just go and hit "reply", please:
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>    c) Ideally: find the original patch on the mailing list and do a
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> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: Hailong Tu <tuhailong@gmail.com>
> Subject: mm/damon/reclaim: fix the timer always stays active
> 
> The timer stays active even if the reclaim mechanism is never enabled.  It
> is unnecessary overhead can be completely avoided by using
> module_param_cb() for enabled flag.
> 
> Link: https://lkml.kernel.org/r/20220421125910.1052459-1-tuhailong@gmail.com
> Signed-off-by: Hailong Tu <tuhailong@gmail.com>
> Cc: SeongJae Park <sj@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Reviewed-by: SeongJae Park <sj@kernel.org>

> ---
> 
>  mm/damon/reclaim.c |   27 +++++++++++++++++++++++++--
>  1 file changed, 25 insertions(+), 2 deletions(-)
> 
> --- a/mm/damon/reclaim.c~mm-damon-reclaim-fix-the-timer-always-stays-active
> +++ a/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 +357,35 @@ static void damon_reclaim_timer_fn(struc
>  			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_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;
> +}
> +
> +static const struct kernel_param_ops enabled_param_ops = {
> +	.set = enabled_store,
> +	.get = param_get_bool,
> +};
> +
> +module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
> +MODULE_PARM_DESC(enabled,
> +	"Enable or disable DAMON_RECLAIM (default: disabled)");
> +
>  static int damon_reclaim_after_aggregation(struct damon_ctx *c)
>  {
>  	struct damos *s;
> _
> 
> Patches currently in -mm which might be from tuhailong@gmail.com are
> 
> mm-damon-reclaim-fix-the-timer-always-stays-active.patch