linux-kernel - 答复: [PATCH V4] mm/damon/reclaim: Fix the timer always stays active

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Message-ID: <HK0PR02MB320269261363F86222CAE2D1DEF49@HK0PR02MB3202.apcprd02.prod.outlook.com>
Date:   Thu, 21 Apr 2022 12:48:10 +0000
From:   涂海龙(Hailong) <tuhailong@...o.com>
To:     SeongJae Park <sj@...nel.org>, Hailong Tu <tuhailong@...il.com>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "gregkh@...gle.com" <gregkh@...gle.com>,
        "surenb@...gle.com" <surenb@...gle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        李春鹏(punk li) <lichunpeng@...o.com>,
        邱长平(Aaron Qiu) <aaron.qiu@...o.com>,
        范国泽(Gordon) <fanguoze@...o.com>,
        王德锁(DeSuo) <wangdesuo@...o.com>,
        李志华(Terry) <lizhihua@...o.com>
Subject: 答复: [PATCH V4] mm/damon/reclaim: Fix the timer always stays active

Hi, SJ
  OK, I will modify it according to your comments

  But I did checkpatch, there was no obvious style problem.
./scripts/checkpatch.pl --no-tree -f mm/damon/reclaim.c
total: 0 errors, 0 warnings, 425 lines checked
mm/damon/reclaim.c has no obvious style problems and is ready for submission.

Yours sincerely
Hailong

-----邮件原件-----
发件人: SeongJae Park <sj@...nel.org>
发送时间: 2022年4月21日 20:41
收件人: Hailong Tu <tuhailong@...il.com>
抄送: akpm@...ux-foundation.org; sj@...nel.org; torvalds@...ux-foundation.org; gregkh@...gle.com; surenb@...gle.com; linux-mm@...ck.org; linux-kernel@...r.kernel.org; 涂海龙(Hailong) <tuhailong@...o.com>; 李春鹏(punk li) <lichunpeng@...o.com>; 邱长平(Aaron Qiu) <aaron.qiu@...o.com>; 范国泽(Gordon) <fanguoze@...o.com>; 王德锁(DeSuo) <wangdesuo@...o.com>; 李志华(Terry) <lizhihua@...o.com>
主题: Re: [PATCH V4] mm/damon/reclaim: Fix the timer always stays active

Hi Hailong,


On Thu, 21 Apr 2022 18:05:24 +0800 Hailong Tu <tuhailong@...il.com> 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_cb() for enabled flag.

As commented to the previous version[1], let's wrap the line at 75 columns.
checkpatch.pl is also complaining.

[1] https://lore.kernel.org/linux-mm/20220421084806.72553-1-sj@kernel.org/

>
> Signed-off-by: Hailong Tu <tuhailong@...il.com>
> ---
>  mm/damon/reclaim.c | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c index
> e34c4d0c4d93..e573e3f50064 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 +357,34 @@ 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;
> +}
> +
> +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)");

I'd prefer 80 columns limit.  Could you please put the string in the next line, like below?

    MODULE_PARM_DESC(enabled,
                 "Enable or disable DAMON_RECLAIM (default: disabled)");


Thanks,
SJ

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