linux-kernel - Re: [PATCH tip/core/rcu 01/11] rcu: Expedite grace periods during suspend/resume

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Message-ID: <20130818031717.GL28923@leaf>
Date:	Sat, 17 Aug 2013 20:17:17 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
	dipankar@...ibm.com, akpm@...ux-foundation.org,
	mathieu.desnoyers@...ymtl.ca, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, dhowells@...hat.com,
	edumazet@...gle.com, darren@...art.com, fweisbec@...il.com,
	sbw@....edu, Borislav Petkov <bp@...en8.de>,
	Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH tip/core/rcu 01/11] rcu: Expedite grace periods during
 suspend/resume

On Sat, Aug 17, 2013 at 06:37:46PM -0700, Paul E. McKenney wrote:
> From: Borislav Petkov <bp@...en8.de>
> 
> CONFIG_RCU_FAST_NO_HZ can increase grace-period durations by up to
> a factor of four, which can result in long suspend and resume times.
> Thus, this commit temporarily switches to expedited grace periods when
> suspending the box and return to normal settings when resuming.
> 
> [ paulmck: This also papers over an audio/irq bug, but hopefully that will
>   be fixed soon. ]
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

This patch still seems like a hack, and there *ought* to be a better
general solution to avoid excessive grace-period latency.  Nonetheless,
in the absence of such a solution,
Reviewed-by: Josh Triplett <josh@...htriplett.org>
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