2022-04-22 17:42:15

by Hailong Tu

Subject: [PATCH v3] mm/damon: 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_call() for enabled flag.

Signed-off-by: Hailong Tu <[email protected]>
---
mm/damon/reclaim.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index e34c4d0c4d93..46505c501cd6 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 +357,27 @@ 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_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, param_get_bool, &enabled, 0600);
+
static int damon_reclaim_after_aggregation(struct damon_ctx *c)
{
struct damos *s;
--
2.25.1

2022-04-22 20:37:30

by SeongJae Park

Subject: Re: [PATCH v3] mm/damon: Fix the timer always stays active

Hi Hailong,


On Thu, 21 Apr 2022 09:06:41 +0800 Hailong Tu <[email protected]> wrote:

> The timer stays active even if the reclaim mechanism is never enabled.

I'd like to make it clear that this change is for DAMON_RECLAIM by making the
first part of the subject 'mm/damon/reclaim:', and adjusting above sentence.

> It is unnecessary overhead can be completely avoided by using module_param_call() for enabled flag.

Let's wrap the line at 75 columns
(https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format).

>
> Signed-off-by: Hailong Tu <[email protected]>
> ---
> mm/damon/reclaim.c | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index e34c4d0c4d93..46505c501cd6 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 +357,27 @@ 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_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, param_get_bool, &enabled, 0600);

module_param_call() is commented as obsolete. Could we use module_param_cb()
instead as suggested by the comment?

> +
> static int damon_reclaim_after_aggregation(struct damon_ctx *c)
> {
> struct damos *s;
> --
> 2.25.1
>


Thanks,
SJ