linux-kernel - Re: irq 16: nobody cared

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Date:	Sun, 21 Apr 2013 21:06:55 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
	tiwai@...e.de
Subject: Re: irq 16: nobody cared

On Sun, Apr 21, 2013 at 11:56:09AM -0700, Paul E. McKenney wrote:
> CONFIG_RCU_FAST_NO_HZ will definitely change the timing, for example,
> increasing grace-period durations by up to a factor of four.
>
> One way to figure out if this is the problem would be to either (1)
> apply the following patch (assuming you have no more than a few tens
> of CPUs)

Only 8 - I'm modest that way :)

> or (2) setting the sysfs rcutree.rcu_expedited variable to 1 just before
> suspending the system.
> 
> Either approach will force RCU to always use the faster expedited
> grace periods for synchronize_rcu() and friends.  They will -not- help
> if someone has open-coded synchronize_rcu() in terms of call_rcu(),
> though.

Right,

# echo 1 > /sys/kernel/rcu_expedited

helped.

No warning, no delay, 2 suspend/resume cycles back-to-back. So, a
probable fix could be to force-enable the expedited grace periods during
suspend...?

Hmmm.

Thanks.

-- 
Regards/Gruss,
    Boris.

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