From: Tang Junhui <[email protected]> Sometimes, Journal takes up a lot of CPU, we need statistics to know what's the journal is doing. So this patch provide some journal statistics: 1) reclaim: how many times the journal try to reclaim resource, usually the journal bucket or/and the pin are exhausted. 2) flush_write: how many times the journal try to flush btree node to cache device, usually the journal bucket are exhausted. 3) retry_flush_write: how many times the journal retry to flush the next btree node, usually the previous tree node have been flushed by other thread. we show these statistic by sysfs interface. Through these statistics We can totally see the status of journal module when the CPU is too high.
Signed-off-by: Tang Junhui <[email protected]> --- drivers/md/bcache/bcache.h | 5 +++++ drivers/md/bcache/journal.c | 5 +++++ drivers/md/bcache/sysfs.c | 15 +++++++++++++++ 3 files changed, 25 insertions(+) diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index abd31e8..0432e28 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -647,6 +647,11 @@ struct cache_set { atomic_long_t writeback_keys_done; atomic_long_t writeback_keys_failed; + + atomic_long_t reclaim; + atomic_long_t flush_write; + atomic_long_t retry_flush_write; + enum { ON_ERROR_UNREGISTER, ON_ERROR_PANIC, diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index 02a98dd..47fd0b8 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -372,6 +372,8 @@ static void btree_flush_write(struct cache_set *c) */ struct btree *b, *best; unsigned i; + + atomic_long_inc(&c->flush_write); retry: best = NULL; @@ -392,6 +394,7 @@ static void btree_flush_write(struct cache_set *c) if (!btree_current_write(b)->journal) { mutex_unlock(&b->write_lock); /* We raced */ + atomic_long_inc(&c->retry_flush_write); goto retry; } @@ -471,6 +474,8 @@ static void journal_reclaim(struct cache_set *c) unsigned iter, n = 0; atomic_t p; + atomic_long_inc(&c->reclaim); + while (!atomic_read(&fifo_front(&c->journal.pin))) fifo_pop(&c->journal.pin, p); diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 234b2f5..0afbf1a 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -65,6 +65,9 @@ read_attribute(state); read_attribute(cache_read_races); +read_attribute(reclaim); +read_attribute(flush_write); +read_attribute(retry_flush_write); read_attribute(writeback_keys_done); read_attribute(writeback_keys_failed); read_attribute(io_errors); @@ -543,6 +546,15 @@ static unsigned bch_average_key_size(struct cache_set *c) sysfs_print(cache_read_races, atomic_long_read(&c->cache_read_races)); + sysfs_print(reclaim, + atomic_long_read(&c->reclaim)); + + sysfs_print(flush_write, + atomic_long_read(&c->flush_write)); + + sysfs_print(retry_flush_write, + atomic_long_read(&c->retry_flush_write)); + sysfs_print(writeback_keys_done, atomic_long_read(&c->writeback_keys_done)); sysfs_print(writeback_keys_failed, @@ -729,6 +741,9 @@ static void bch_cache_set_internal_release(struct kobject *k) &sysfs_bset_tree_stats, &sysfs_cache_read_races, + &sysfs_reclaim, + &sysfs_flush_write, + &sysfs_retry_flush_write, &sysfs_writeback_keys_done, &sysfs_writeback_keys_failed, -- 1.8.3.1
