Hi Shaohua, On Thu, May 28, 2015 at 05:33:48PM -0700, Shaohua Li 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 I happened to have considered something similar but with slight different before. The stuff I came up with is to make active_stripes per stripe hash as well, with which your above concerns could be eliminated. I even wrote the code, and it became a bit uglier than I thought, what's more, I see no obvious performance benifit from it. I then gave it up and didn't sent it out for bothering you guys. Well, I wrote that code before I came up with this lock contention fix[0], it might be a different story if I wrote such code based on the fix. If you are interested, I guess I could cook it up again and do some tests. [0]: http://git.neil.brown.name/?p=md.git;a=commit;h=970e1a16559e1865b429e0ec408c9a06f2f83795 BTW, the reason I want to make active_stripes per stripe hash is to keep the semantics of holding on to wake up processes before we get 1/4 stripes available, which, IMO, is for performance consideration. And to be honest, I don't have too much clue how the performance will behave differently in such two cases. I'm gonna to do some test to figure it out, if you think that's necessary. --yliu > 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); > -- > 1.8.1 > > -- > 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 -- 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
