* Re: kernel building regression on 32-rc5 kernel
[not found] <F7C8A4D3A9905B45A80E4C194793FA651553C00D3D@PDSMSX501.ccr.corp.intel.com>
@ 2009-11-03 18:32 ` Jens Axboe
2009-11-04 1:21 ` Alex Shi
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2009-11-03 18:32 UTC (permalink / raw)
To: Shi, Alex; +Cc: linux-kernel
On Tue, Nov 03 2009, Shi, Alex wrote:
> I found the kernel building will have about 20%~ 30% regressions on
> our NHM machines. My kernel build do the following things 15 times:
>
> make mrproper; echo \"3\">/proc/sys/vm/drop_caches; make defconfig;
> make -j${2timescpunumbers}
>
>
>
> Bisect found it is due to the commitment:
>
> commit a6151c3a5c8e1ff5a28450bc8d6a99a2a0add0a7
I looked over that commit and found one typo, can you check with this
patch applied?
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 069a610..5802e32 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2051,7 +2051,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
* it's a metadata request and the current queue is doing regular IO.
*/
if (rq_is_meta(rq) && !cfqq->meta_pending)
- return false;
+ return true;
/*
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
--
Jens Axboe
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: kernel building regression on 32-rc5 kernel
2009-11-03 18:32 ` kernel building regression on 32-rc5 kernel Jens Axboe
@ 2009-11-04 1:21 ` Alex Shi
2009-11-04 7:40 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Alex Shi @ 2009-11-04 1:21 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel
Yes, the performance recovered with this patch on 32-rc6 kernel.
On Wed, 2009-11-04 at 02:32 +0800, Jens Axboe wrote:
> On Tue, Nov 03 2009, Shi, Alex wrote:
> > I found the kernel building will have about 20%~ 30% regressions on
> > our NHM machines. My kernel build do the following things 15 times:
> >
> > make mrproper; echo \"3\">/proc/sys/vm/drop_caches; make defconfig;
> > make -j${2timescpunumbers}
> >
> >
> >
> > Bisect found it is due to the commitment:
> >
> > commit a6151c3a5c8e1ff5a28450bc8d6a99a2a0add0a7
>
> I looked over that commit and found one typo, can you check with this
> patch applied?
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 069a610..5802e32 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -2051,7 +2051,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
> * it's a metadata request and the current queue is doing regular IO.
> */
> if (rq_is_meta(rq) && !cfqq->meta_pending)
> - return false;
> + return true;
>
> /*
> * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: kernel building regression on 32-rc5 kernel
2009-11-04 1:21 ` Alex Shi
@ 2009-11-04 7:40 ` Jens Axboe
0 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2009-11-04 7:40 UTC (permalink / raw)
To: Alex Shi; +Cc: linux-kernel
On Wed, Nov 04 2009, Alex Shi wrote:
> On Wed, 2009-11-04 at 02:32 +0800, Jens Axboe wrote:
> > On Tue, Nov 03 2009, Shi, Alex wrote:
> > > I found the kernel building will have about 20%~ 30% regressions on
> > > our NHM machines. My kernel build do the following things 15 times:
> > >
> > > make mrproper; echo \"3\">/proc/sys/vm/drop_caches; make defconfig;
> > > make -j${2timescpunumbers}
> > >
> > >
> > >
> > > Bisect found it is due to the commitment:
> > >
> > > commit a6151c3a5c8e1ff5a28450bc8d6a99a2a0add0a7
> >
> > I looked over that commit and found one typo, can you check with this
> > patch applied?
> >
> > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> > index 069a610..5802e32 100644
> > --- a/block/cfq-iosched.c
> > +++ b/block/cfq-iosched.c
> > @@ -2051,7 +2051,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
> > * it's a metadata request and the current queue is doing regular IO.
> > */
> > if (rq_is_meta(rq) && !cfqq->meta_pending)
> > - return false;
> > + return true;
> >
> > /*
> > * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
>
> Yes, the performance recovered with this patch on 32-rc6 kernel.
Great! The patch just missed -rc6, as I had already queued it up and
asked for a pull. It's in current -git. Thanks a lot for reporting!
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* kernel building regression on 32-rc5 kernel
@ 2009-11-03 14:42 Shi, Alex
0 siblings, 0 replies; 4+ messages in thread
From: Shi, Alex @ 2009-11-03 14:42 UTC (permalink / raw)
To: linux-kernel
I found the kernel building will have about 20%~ 30% regressions on our NHM machines. My kernel build do the following things 15 times:
make mrproper; echo \"3\">/proc/sys/vm/drop_caches; make defconfig; make -j${2timescpunumbers}
Bisect found it is due to the commitment:
commit a6151c3a5c8e1ff5a28450bc8d6a99a2a0add0a7
Author: Jens Axboe <jens.axboe@oracle.com>
Date: Wed Oct 7 20:02:57 2009 +0200
cfq-iosched: apply bool value where we return 0/1
It quite makes me confused, but after reverting this patch the performance recovered. I analyzed the vmstat and "perf record" results, But did not find something strange. Just the "perf stat" shows something different.
Perf stat output of Rc5 kernel:
850121.335684 task-clock-msecs # 1.035 CPUs
867280 context-switches # 0.001 M/sec
266319 CPU-migrations # 0.000 M/sec
76663435 page-faults # 0.090 M/sec
2697372004020 cycles # 3172.926 M/sec (scaled from 100.00%)
2779762582367 instructions # 1.031 IPC (scaled from 100.00%)
14230675659 cache-references # 16.740 M/sec (scaled from 100.00%)
3048368747 cache-misses # 3.586 M/sec (scaled from 100.00%)
821.432570507 seconds time elapsed
Perf stat output of rc5 without the commit kernel:
900054.808787 task-clock-msecs # 1.237 CPUs
845152 context-switches # 0.001 M/sec
252689 CPU-migrations # 0.000 M/sec
77495232 page-faults # 0.086 M/sec
2470286471361 cycles # 2744.596 M/sec
2684134677043 instructions # 1.087 IPC
14685367142 cache-references # 16.316 M/sec
2869381827 cache-misses # 3.188 M/sec
727.415980216 seconds time elapsed
BRG
Alex
^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <F7C8A4D3A9905B45A80E4C194793FA651553C00D3D@PDSMSX501.ccr.corp.intel.com>
2009-11-03 18:32 ` kernel building regression on 32-rc5 kernel Jens Axboe
2009-11-04 1:21 ` Alex Shi
2009-11-04 7:40 ` Jens Axboe
2009-11-03 14:42 Shi, Alex
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