linux-kernel - Re: [RFC PATCH v2 1/2] ceph: allow schedule_delayed() callers to set delay for workqueue

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Date:   Tue, 29 Jun 2021 12:14:37 +0200
From:   Ilya Dryomov <idryomov@...il.com>
To:     Luis Henriques <lhenriques@...e.de>
Cc:     Jeff Layton <jlayton@...nel.org>,
        Ceph Development <ceph-devel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2 1/2] ceph: allow schedule_delayed() callers to set
 delay for workqueue

On Tue, Jun 29, 2021 at 11:47 AM Luis Henriques <lhenriques@...e.de> wrote:
>
> Allow schedule_delayed() callers to explicitly set the delay value instead
> of defaulting to a 5 secs value.
>
> Signed-off-by: Luis Henriques <lhenriques@...e.de>
> ---
>  fs/ceph/mds_client.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index e5af591d3bd4..08c76bf57fb1 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -4502,13 +4502,18 @@ void inc_session_sequence(struct ceph_mds_session *s)
>  }
>
>  /*
> - * delayed work -- periodically trim expired leases, renew caps with mds
> + * delayed work -- periodically trim expired leases, renew caps with mds.  If
> + * the @delay parameter is set to 0 or if it's more than 5 secs, the default
> + * workqueue delay value of 5 secs will be used.
>   */
> -static void schedule_delayed(struct ceph_mds_client *mdsc)
> +static void schedule_delayed(struct ceph_mds_client *mdsc, unsigned long delay)
>  {
> -       int delay = 5;
> -       unsigned hz = round_jiffies_relative(HZ * delay);
> -       schedule_delayed_work(&mdsc->delayed_work, hz);
> +       unsigned long max_delay = round_jiffies_relative(HZ * 5);
> +
> +       /* 5 secs default delay */
> +       if (!delay || (delay > max_delay))
> +               delay = max_delay;
> +       schedule_delayed_work(&mdsc->delayed_work, delay);

Hi Luis,

Is there a reason to not round the non-default delay?  Does it need to
be precise?

Thanks,

                Ilya