On Thu, Oct 10, 2019 at 11:41:33AM -0400, Josef Bacik wrote:
> On Mon, Oct 07, 2019 at 04:17:41PM -0400, Dennis Zhou wrote:
> > Use the number of discardable extents to help guide our discard delay
> > interval. This value is reevaluated every transaction commit.
> >
> > Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
> > ---
> > fs/btrfs/ctree.h | 2 ++
> > fs/btrfs/discard.c | 31 +++++++++++++++++++++++++++++--
> > fs/btrfs/discard.h | 3 +++
> > fs/btrfs/extent-tree.c | 4 +++-
> > fs/btrfs/sysfs.c | 30 ++++++++++++++++++++++++++++++
> > 5 files changed, 67 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> > index 8479ab037812..b0823961d049 100644
> > --- a/fs/btrfs/ctree.h
> > +++ b/fs/btrfs/ctree.h
> > @@ -449,6 +449,8 @@ struct btrfs_discard_ctl {
> > struct list_head discard_list[BTRFS_NR_DISCARD_LISTS];
> > atomic_t discard_extents;
> > atomic64_t discardable_bytes;
> > + atomic_t delay;
> > + atomic_t iops_limit;
> > };
> >
> > /* delayed seq elem */
> > diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
> > index 75a2ff14b3c0..c7afb5f8240d 100644
> > --- a/fs/btrfs/discard.c
> > +++ b/fs/btrfs/discard.c
> > @@ -15,6 +15,11 @@
> >
> > #define BTRFS_DISCARD_DELAY (300ULL * NSEC_PER_SEC)
> >
> > +/* target discard delay in milliseconds */
> > +#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60ULL * MSEC_PER_SEC)
> > +#define BTRFS_DISCARD_MAX_DELAY (10000UL)
> > +#define BTRFS_DISCARD_MAX_IOPS (10UL)
> > +
> > static struct list_head *
> > btrfs_get_discard_list(struct btrfs_discard_ctl *discard_ctl,
> > struct btrfs_block_group_cache *cache)
> > @@ -170,10 +175,12 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
> >
> > cache = find_next_cache(discard_ctl, now);
> > if (cache) {
> > - u64 delay = 0;
> > + u64 delay = atomic_read(&discard_ctl->delay);
> >
> > if (now < cache->discard_delay)
> > - delay = nsecs_to_jiffies(cache->discard_delay - now);
> > + delay = max_t(u64, delay,
> > + nsecs_to_jiffies(cache->discard_delay -
> > + now));
>
> Small nit, instead
>
> delay = nsecs_to_jiffies(cache->discard_delay - now);
> delay = max_t(u64, delay,
> atomic_read(&discard_ctl->delay);
>
> Looks a little cleaner. Otherwise
Hmmm. Does that work if now > cache->discard_delay? I'm just worried
about the max_t with type u64.
>
> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
>
> Thanks,
>
> Josef
Thanks,
Dennis
