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>
---
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
