linux-kernel - Re: Bisected post-3.9 regression: Resume takes 5 times as much time as with v3.9

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Date:	Sun, 12 May 2013 18:27:17 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	paulmck@...ux.vnet.ibm.com,
	"Paul E. McKenney" <paul.mckenney@...aro.org>,
	linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>
Subject: Re: Bisected post-3.9 regression: Resume takes 5 times as much time
 as with v3.9

On Sun, May 12, 2013 at 06:13:34PM +0200, Bjørn Mork wrote:
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 6934238..2dcbf84 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -3103,9 +3103,11 @@ static int rcu_pm_notify(struct notifier_block *self,
>  {
>  	switch (action) {
>  	case PM_HIBERNATION_PREPARE:
> +	case PM_SUSPEND_PREPARE:
>  		rcu_expedited = 1;
>  		break;
> -	case PM_POST_RESTORE:
> +	case PM_POST_HIBERNATION:
> +	case PM_POST_SUSPEND:
>  		rcu_expedited = 0;
>  		break;
>  	default:

If I'm reading Documentation/power/notifiers.txt correctly, we only need
PM_HIBERNATION_PREPARE when we go to sleep (whatever hibernation method
we use) and PM_POST_HIBERNATION when we restore.

I don't think it matters for expediting RCU grace periods whether
we had an error during resume or not and I'd basically want to set
rcu_expedited to 0 unconditionally when resuming..

Hmm.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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