linux-kernel - Re: [tg_shares_up rewrite v3 09/11] sched: demand based update_cfs

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Message-ID: <1289559198.2084.214.camel@laptop>
Date:	Fri, 12 Nov 2010 11:53:18 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Paul Turner <pjt@...gle.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Chris Friesen <cfriesen@...tel.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Pierre Bourdon <pbourdon@...ellency.fr>,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	Karl Rister <kmr@...ibm.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	David Miller <davem@...emloft.net>
Subject: Re: [tg_shares_up rewrite v3 09/11] sched: demand based
 update_cfs_load()

On Thu, 2010-11-11 at 19:24 -0800, Paul Turner wrote:
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> +       cfs_rq->load_unacc_exec_time += delta_exec;
> +       if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window)
> {
> +               update_cfs_load(cfs_rq);
> +               update_cfs_shares(cfs_rq, 0);

Why not:
+		cfs_rq->load_unacc_exec_time -= sysctl_sched_shares_window;

(although you probably want to read the sysctl value into a local
variable using ACCESS_ONCE() and use that for both cases).

> +       }
> +#endif
>  }
>  
>  static void update_curr(struct cfs_rq *cfs_rq)
> @@ -713,6 +724,7 @@ static void update_cfs_load(struct cfs_r
>         }
>  
>         cfs_rq->load_stamp = now;
> +       cfs_rq->load_unacc_exec_time = 0; 

and drop this one?
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