Messages in this thread Patch in this message | | | Date | Fri, 4 Dec 2009 16:21:20 +0800 | From | Shaohua Li <> | Subject | Re: [PATCH]cfq-iosched: make nonrot check logic consistent |
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On Thu, Dec 03, 2009 at 08:00:21PM +0800, Jens Axboe wrote: > On Thu, Dec 03 2009, Jens Axboe wrote: > > On Thu, Dec 03 2009, Shaohua Li wrote: > > > Send again, last post seems lost. > > > > > > cfq_arm_slice_timer() has logic to disable idle window for SSD device. The same > > > thing should be done at cfq_select_queue() too, otherwise we will still see > > > idle window. This makes the nonrot check logic consistent in cfq. > > > Tests in a intel SSD with low_latency knob close, below patch can triple disk > > > thoughput for muti-thread sequential read. > > > > > > Signed-off-by: Shaohua Li <shaohua.li@intel.com> > > > --- > > > block/cfq-iosched.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > Index: linux/block/cfq-iosched.c > > > =================================================================== > > > --- linux.orig/block/cfq-iosched.c 2009-11-11 13:44:00.000000000 +0800 > > > +++ linux/block/cfq-iosched.c 2009-11-11 13:45:33.000000000 +0800 > > > @@ -1215,7 +1215,8 @@ static struct cfq_queue *cfq_select_queu > > > * conditions to happen (or time out) before selecting a new queue. > > > */ > > > if (timer_pending(&cfqd->idle_slice_timer) || > > > - (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { > > > + (cfqq->dispatched && cfq_cfqq_idle_window(cfqq) > > > + && !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))) { > > > cfqq = NULL; > > > goto keep_queue; > > > } > > > > Thanks, applied to 2.6.33 queue. > > On second check, we now hide that logic in cfq_should_idle() and as such > your patch no longer applies. I suggest you re-test with -next or my > for-2.6.33 branch, it has a big number of pending CFQ updates for > 2.6.33. -next has the same issue too. Below is updated patch.
cfq_arm_slice_timer() has logic to disable idle window for SSD device. The same thing should be done at cfq_select_queue() too, otherwise we will still see idle window. This makes the nonrot check logic consistent in cfq. Tests in a intel SSD with low_latency knob close, below patch can triple disk thoughput for muti-thread sequential read.
Signed-off-by: Shaohua Li <shaohua.li@intel.com> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 08b057b..abc5206 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1795,7 +1795,8 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) return false; /* We do for queues that were marked with idle window flag. */ - if (cfq_cfqq_idle_window(cfqq)) + if (cfq_cfqq_idle_window(cfqq) && + !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) return true; /*
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