Re: sysbench+mysql(oltp, readonly) 30% regression with 2.6.26-rc1

[Mike Galbraith <efault@gmx.de>]

On Thu, 2008-05-08 at 17:01 +0800, Zhang, Yanmin wrote:
> On Thu, 2008-05-08 at 10:00 +0200, Mike Galbraith wrote:

> > Hm.  I was doing some sysbench+postgress(oltp, ro) testing on my little
> > Q6600 box this morning, and saw a different picture.

> How many cpu are in the Q6600?

1.

> > 
> > In attached pdf, .bkl refers to Linus' BKL patch, .weight is the weight
> > fix, both are applied to git.today.  The script I used is also attached.
> With my 8-core stoakley (using mysql):
> 1) 2.6.25:
> Number of threads: 6
>     read/write requests:                 8025024 (66874.53 per sec.)
> Number of threads: 8
>     read/write requests:                 9132816 (76106.14 per sec.)
> Number of threads: 10
>     read/write requests:                 9244998 (77040.75 per sec.)
> Number of threads: 12
>     read/write requests:                 8994174 (74950.36 per sec.)
> Number of threads: 14
>     read/write requests:                 9051322 (75426.54 per sec.)
> Number of threads: 16
>     read/write requests:                 9015412 (75126.93 per sec.)
> 
> 2) 2.6.26-rc1:
> Number of threads: 6
>     read/write requests:                 5754056 (47949.87 per sec.)
> Number of threads: 8
>     read/write requests:                 6528480 (54403.29 per sec.)
> Number of threads: 10
>     read/write requests:                 6444690 (53705.16 per sec.)
> Number of threads: 12
>     read/write requests:                 6544258 (54534.23 per sec.)
> Number of threads: 14
>     read/write requests:                 6796650 (56637.65 per sec.)
> Number of threads: 16
>     read/write requests:                 6718110 (55983.18 per sec.)
> 
> 3) 2.6.26-rc1+weight
> Number of threads: 16
> 	read/write requests:                 3219076 (26824.22 per sec.)
> 
> I'm not sure if more cpu could introduce more contention in this test.

-rc1.  Do you have the fix below applied?

commit a992241de614dd2b7c97a9ba64e28c0e563f19bf
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date:   Mon May 5 23:56:17 2008 +0200

    sched: fix normalized sleeper
    
    Normalized sleeper uses calc_delta*() which requires that the rq load is
    already updated, so move account_entity_enqueue() before place_entity()
    
    Tested-by: Frans Pop <elendil@planet.nl>
    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 89fa32b..1295ddc 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -682,6 +682,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
 	 * Update run-time statistics of the 'current'.
 	 */
 	update_curr(cfs_rq);
+	account_entity_enqueue(cfs_rq, se);
 
 	if (wakeup) {
 		place_entity(cfs_rq, se, 0);
@@ -692,7 +693,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
 	check_spread(cfs_rq, se);
 	if (se != cfs_rq->curr)
 		__enqueue_entity(cfs_rq, se);
-	account_entity_enqueue(cfs_rq, se);
 }
 
 static void update_avg(u64 *avg, u64 sample)