Messages in this thread | | | Date | Thu, 14 Jan 2010 10:46:40 +0800 | From | Gui Jianfeng <> | Subject | Re: [PATCH]cfq-iosched: don't stop async queue with async requests pending |
| |
Shaohua Li wrote: > My SSD speed of direct write is about 80m/s, while I test page writeback, > the speed can only go to 68m/s. Below patch fixes this. > It appears we missused cfq_should_idle in cfq_may_dispatch. cfq_should_idle > means a queue should idle because it's seekless sync queue or it's the last queue, > which is to maintain service tree time slice. So it doesn't mean the > last queue is always a sync queue. If the last queue is asyn queue, > we definitely shouldn't stop dispatch requests because of pending async > requests. > > Signed-off-by: Shaohua Li <shaohua.li@intel.com> > > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c > index 918c7fd..8198079 100644 > --- a/block/cfq-iosched.c > +++ b/block/cfq-iosched.c > @@ -2222,7 +2222,8 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) > /* > * Drain async requests before we start sync IO > */ > - if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) > + if (cfq_cfqq_sync(cfqq) && cfq_should_idle(cfqd, cfqq) > + && cfqd->rq_in_driver[BLK_RW_ASYNC]) > return false;
It seems only sync queue could open the idle window, so i don't think we really need this.
Thanks, Gui
| |