On Mon, Oct 07, 2019 at 04:17:42PM -0400, Dennis Zhou wrote:
> Provide an ability to rate limit based on mbps in addition to the iops
> delay calculated from number of discardable extents.
>
> Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 2 ++
> fs/btrfs/discard.c | 11 +++++++++++
> fs/btrfs/sysfs.c | 30 ++++++++++++++++++++++++++++++
> 3 files changed, 43 insertions(+)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index b0823961d049..e81f699347e0 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -447,10 +447,12 @@ struct btrfs_discard_ctl {
> spinlock_t lock;
> struct btrfs_block_group_cache *cache;
> struct list_head discard_list[BTRFS_NR_DISCARD_LISTS];
> + u64 prev_discard;
> atomic_t discard_extents;
> atomic64_t discardable_bytes;
> atomic_t delay;
> atomic_t iops_limit;
> + atomic64_t bps_limit;
> };
>
> /* delayed seq elem */
> diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
> index c7afb5f8240d..072c73f48297 100644
> --- a/fs/btrfs/discard.c
> +++ b/fs/btrfs/discard.c
> @@ -176,6 +176,13 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
> cache = find_next_cache(discard_ctl, now);
> if (cache) {
> u64 delay = atomic_read(&discard_ctl->delay);
> + s64 bps_limit = atomic64_read(&discard_ctl->bps_limit);
> +
> + if (bps_limit)
> + delay = max_t(u64, delay,
> + msecs_to_jiffies(MSEC_PER_SEC *
> + discard_ctl->prev_discard /
> + bps_limit));
I forget, are we allowed to do 0 / some value? I feel like I did this at some
point with io.latency and it panic'ed and was very confused. Maybe I'm just
misremembering.
And a similar nit, maybe we just do
u64 delay = atomic_read(&discard_ctl->delay);
u64 bps_delay = atomic64_read(&discard_ctl->bps_limit);
if (bps_delay)
bps_delay = msecs_to_jiffies(MSEC_PER_SEC * blah)
delay = max(delay, bps_delay);
Or something else. Thanks,
Josef
