On Wed, 13 Nov 2019, Coly Li wrote:
> For writeback mode, if there is no regular I/O request for a while,
> the writeback rate will be set to the maximum value (1TB/s for now).
> This is good for most of the storage workload, but there are still
> people don't what the maximum writeback rate in I/O idle time.
>
> This patch adds a sysfs interface file idle_max_writeback_rate to
> permit people to disable maximum writeback rate. Then the minimum
> writeback rate can be advised by writeback_rate_minimum in the
> bcache device's sysfs interface.
>
> Reported-by: Christian Balzer <chibi@xxxxxxx>
> Signed-off-by: Coly Li <colyli@xxxxxxx>
This fixes a bug for Christian, add cc stable?
-Eric
--
Eric Wheeler
> ---
> drivers/md/bcache/bcache.h | 1 +
> drivers/md/bcache/super.c | 1 +
> drivers/md/bcache/sysfs.c | 7 +++++++
> drivers/md/bcache/writeback.c | 4 ++++
> 4 files changed, 13 insertions(+)
>
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index 50241e045c70..9198c1b480d9 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -724,6 +724,7 @@ struct cache_set {
> unsigned int gc_always_rewrite:1;
> unsigned int shrinker_disabled:1;
> unsigned int copy_gc_enabled:1;
> + unsigned int idle_max_writeback_rate_enabled:1;
>
> #define BUCKET_HASH_BITS 12
> struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index d1352fcc6ff2..77e9869345e7 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1834,6 +1834,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
> c->congested_read_threshold_us = 2000;
> c->congested_write_threshold_us = 20000;
> c->error_limit = DEFAULT_IO_ERROR_LIMIT;
> + c->idle_max_writeback_rate_enabled = 1;
> WARN_ON(test_and_clear_bit(CACHE_SET_IO_DISABLE, &c->flags));
>
> return c;
> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
> index 627dcea0f5b6..733e2ddf3c78 100644
> --- a/drivers/md/bcache/sysfs.c
> +++ b/drivers/md/bcache/sysfs.c
> @@ -134,6 +134,7 @@ rw_attribute(expensive_debug_checks);
> rw_attribute(cache_replacement_policy);
> rw_attribute(btree_shrinker_disabled);
> rw_attribute(copy_gc_enabled);
> +rw_attribute(idle_max_writeback_rate);
> rw_attribute(gc_after_writeback);
> rw_attribute(size);
>
> @@ -747,6 +748,8 @@ SHOW(__bch_cache_set)
> sysfs_printf(gc_always_rewrite, "%i", c->gc_always_rewrite);
> sysfs_printf(btree_shrinker_disabled, "%i", c->shrinker_disabled);
> sysfs_printf(copy_gc_enabled, "%i", c->copy_gc_enabled);
> + sysfs_printf(idle_max_writeback_rate, "%i",
> + c->idle_max_writeback_rate_enabled);
> sysfs_printf(gc_after_writeback, "%i", c->gc_after_writeback);
> sysfs_printf(io_disable, "%i",
> test_bit(CACHE_SET_IO_DISABLE, &c->flags));
> @@ -864,6 +867,9 @@ STORE(__bch_cache_set)
> sysfs_strtoul_bool(gc_always_rewrite, c->gc_always_rewrite);
> sysfs_strtoul_bool(btree_shrinker_disabled, c->shrinker_disabled);
> sysfs_strtoul_bool(copy_gc_enabled, c->copy_gc_enabled);
> + sysfs_strtoul_bool(idle_max_writeback_rate,
> + c->idle_max_writeback_rate_enabled);
> +
> /*
> * write gc_after_writeback here may overwrite an already set
> * BCH_DO_AUTO_GC, it doesn't matter because this flag will be
> @@ -954,6 +960,7 @@ static struct attribute *bch_cache_set_internal_files[] = {
> &sysfs_gc_always_rewrite,
> &sysfs_btree_shrinker_disabled,
> &sysfs_copy_gc_enabled,
> + &sysfs_idle_max_writeback_rate,
> &sysfs_gc_after_writeback,
> &sysfs_io_disable,
> &sysfs_cutoff_writeback,
> diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
> index d60268fe49e1..4a40f9eadeaf 100644
> --- a/drivers/md/bcache/writeback.c
> +++ b/drivers/md/bcache/writeback.c
> @@ -122,6 +122,10 @@ static void __update_writeback_rate(struct cached_dev *dc)
> static bool set_at_max_writeback_rate(struct cache_set *c,
> struct cached_dev *dc)
> {
> + /* Don't sst max writeback rate if it is disabled */
> + if (!c->idle_max_writeback_rate_enabled)
> + return false;
> +
> /* Don't set max writeback rate if gc is running */
> if (!c->gc_mark_valid)
> return false;
> --
> 2.16.4
>
>
