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 <[email protected]>
---
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;
}
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 <[email protected]>
> ---
> 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.
--
Jens Axboe
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 <[email protected]>
> > ---
> > 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.
--
Jens Axboe
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 <[email protected]>
> > > ---
> > > 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 <[email protected]>
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;
/*