On Fri, May 29, 2015 at 03:23:16PM +1000, NeilBrown wrote: > On Thu, 28 May 2015 17:33:48 -0700 Shaohua Li <shli@xxxxxx> wrote: > > > Since we have several stripe hash list, the conf->active_stripes doesn't > > determine if there is free stripe in a specific hash list, so delete the > > check. After this, the R5_INACTIVE_BLOCKED check is inappropriate. There > > is no point not to wakeup a task if there is free stripe. > > > > Signed-off-by: Shaohua Li <shli@xxxxxx> > > --- > > drivers/md/raid5.c | 6 +----- > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > > index 67626f3..4b5a03c 100644 > > --- a/drivers/md/raid5.c > > +++ b/drivers/md/raid5.c > > @@ -687,11 +687,7 @@ get_active_stripe(struct r5conf *conf, sector_t sector, > > &conf->cache_state); > > wait_event_lock_irq( > > conf->wait_for_stripe, > > - !list_empty(conf->inactive_list + hash) && > > - (atomic_read(&conf->active_stripes) > > - < (conf->max_nr_stripes * 3 / 4) > > - || !test_bit(R5_INACTIVE_BLOCKED, > > - &conf->cache_state)), > > + !list_empty(conf->inactive_list + hash), > > *(conf->hash_locks + hash)); > > clear_bit(R5_INACTIVE_BLOCKED, > > &conf->cache_state); > > Have you actually tested this? Because I do remember why I put that code in > and it made a very real performance improvement. > > The idea is that once we run out of free stripes, we wait until there a lots > available. That improves opportunities for batching. > > So I would definitely needs some performance numbers with a patch like this. I didn't realize this is related to performance. Your explaintation makes a lot of sense, please ignore this. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
