Re: kernel building regression on 32-rc5 kernel

[Alex Shi]

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.
> 

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