lkml.org 
[lkml]   [2021]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.15 061/171] mm/damon/core: fix fake load reports due to uninterruptible sleeps
    Date
    From: SeongJae Park <sj@kernel.org>

    commit 70e9274805fccfd175d0431a947bfd11ee7df40e upstream.

    Because DAMON sleeps in uninterruptible mode, /proc/loadavg reports fake
    load while DAMON is turned on, though it is doing nothing. This can
    confuse users[1]. To avoid the case, this commit makes DAMON sleeps in
    idle mode.

    [1] https://lore.kernel.org/all/11868371.O9o76ZdvQC@natalenko.name/

    Link: https://lkml.kernel.org/r/20211126145015.15862-3-sj@kernel.org
    Fixes: 2224d8485492 ("mm: introduce Data Access MONitor (DAMON)")
    Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
    Signed-off-by: SeongJae Park <sj@kernel.org>
    Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
    Cc: John Stultz <john.stultz@linaro.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    mm/damon/core.c | 14 +++++++++++---
    1 file changed, 11 insertions(+), 3 deletions(-)

    --- a/mm/damon/core.c
    +++ b/mm/damon/core.c
    @@ -357,6 +357,15 @@ int damon_start(struct damon_ctx **ctxs,
    return err;
    }

    +static void kdamond_usleep(unsigned long usecs)
    +{
    + /* See Documentation/timers/timers-howto.rst for the thresholds */
    + if (usecs > 20 * 1000)
    + schedule_timeout_idle(usecs_to_jiffies(usecs));
    + else
    + usleep_idle_range(usecs, usecs + 1);
    +}
    +
    /*
    * __damon_stop() - Stops monitoring of given context.
    * @ctx: monitoring context
    @@ -370,8 +379,7 @@ static int __damon_stop(struct damon_ctx
    ctx->kdamond_stop = true;
    mutex_unlock(&ctx->kdamond_lock);
    while (damon_kdamond_running(ctx))
    - usleep_range(ctx->sample_interval,
    - ctx->sample_interval * 2);
    + kdamond_usleep(ctx->sample_interval);
    return 0;
    }
    mutex_unlock(&ctx->kdamond_lock);
    @@ -670,7 +678,7 @@ static int kdamond_fn(void *data)
    ctx->callback.after_sampling(ctx))
    set_kdamond_stop(ctx);

    - usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
    + kdamond_usleep(ctx->sample_interval);

    if (ctx->primitive.check_accesses)
    max_nr_accesses = ctx->primitive.check_accesses(ctx);

    \
     
     \ /
      Last update: 2021-12-13 11:10    [W:4.168 / U:0.216 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site