linux-kernel - Re: [patch v8 9/9] sched/tg: remove blocked_load

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Message-ID: <20130617093838.GN3204@twins.programming.kicks-ass.net>
Date:	Mon, 17 Jun 2013 11:38:38 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Alex Shi <alex.shi@...el.com>
Cc:	mingo@...hat.com, tglx@...utronix.de, akpm@...ux-foundation.org,
	bp@...en8.de, pjt@...gle.com, namhyung@...nel.org, efault@....de,
	morten.rasmussen@....com, vincent.guittot@...aro.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, mgorman@...e.de, riel@...hat.com,
	wangyun@...ux.vnet.ibm.com, Jason Low <jason.low2@...com>,
	Changlong Xie <changlongx.xie@...el.com>, sgruszka@...hat.com,
	fweisbec@...il.com
Subject: Re: [patch v8 9/9] sched/tg: remove blocked_load_avg in balance

On Fri, Jun 07, 2013 at 03:20:52PM +0800, Alex Shi wrote:
> blocked_load_avg sometime is too heavy and far bigger than runnable load
> avg, that make balance make wrong decision. So remove it.
> 
> Changlong tested this patch, found ltp cgroup stress testing get better
> performance: https://lkml.org/lkml/2013/5/23/65
> ---
> 3.10-rc1          patch1-7         patch1-8
> duration=764   duration=754   duration=750
> duration=764   duration=754   duration=751
> duration=763   duration=755   duration=751
> 
> duration means the seconds of testing cost.
> ---
> 
> And Jason also tested this patchset on his 8 sockets machine:
> https://lkml.org/lkml/2013/5/29/673
> ---
> When using a 3.10-rc2 tip kernel with patches 1-8, there was about a 40%
> improvement in performance of the workload compared to when using the
> vanilla 3.10-rc2 tip kernel with no patches. When using a 3.10-rc2 tip
> kernel with just patches 1-7, the performance improvement of the
> workload over the vanilla 3.10-rc2 tip kernel was about 25%.
> ---
> 
> Signed-off-by: Alex Shi <alex.shi@...el.com>
> Tested-by: Changlong Xie <changlongx.xie@...el.com>
> Tested-by: Jason Low <jason.low2@...com>
> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 3aa1dc0..985d47e 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1358,7 +1358,7 @@ static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
>  	struct task_group *tg = cfs_rq->tg;
>  	s64 tg_contrib;
>  
> -	tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
> +	tg_contrib = cfs_rq->runnable_load_avg;
>  	tg_contrib -= cfs_rq->tg_load_contrib;
>  
>  	if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) {

PJT ping! ;-)
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