LGTM except for formatting / an extra newline (will fix) -- in my test
branch for possible 4.16
Reviewed-by: Michael Lyle <mlyle@xxxxxxxx>
On 01/26/2018 12:23 AM, tang.junhui@xxxxxxxxxx wrote:
> From: Tang Junhui <tang.junhui@xxxxxxxxxx>
>
> 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 <tang.junhui@xxxxxxxxxx>
> ---
> 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,
>
>
