Hi,

On Fri, Oct 19, 2012 at 04:00:27PM +0200, Peter Zijlstra wrote:

On Thu, 2012-10-18 at 08:51 +0300, Felipe Balbi wrote:

quoted

quoted

So the primary question remains: is RT runtime supposed to include the
time spent suspended?  I suspect not. 

you might be right there, though we need Thomas or Peter to answer :-s 

re, sorry both tglx and I have been traveling, he still is, I'm trying
to play catch-up :-)

Anyway, yeah I'm somewhat surprised the clock is 'running' when the
machine isn't. From what I could gather, this is !x86 hardware, right?

x86 explicitly makes sure our clocks are 'stopped' during suspend, see
commit cd7240c0b900eb6d690ccee088a6c9b46dae815a.

Can you do something similar for ARM? A quick look at
arch/arm/kernel/sched_clock.c shows there's already suspend/resume
hooks, do they do the wrong thing?

if I understand correctly, then below should be enough. I did't test it
though:

diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 87ba8dd..c9260e6 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c

@@ -116,7 +116,7 @@ int __init omap_init_clocksource_32k(void __iomem *vbase)
 		return ret;
 	}
 
-	setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
+	setup_sched_clock_needs_suspend(omap_32k_read_sched_clock, 32, 32768);
 	register_persistent_clock(NULL, omap_read_persistent_clock);
 	pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
 

Russell, would you have any comments here ? Should we make sure all ARMs
call setup_sched_clock_needs_suspend() and 'stop' counting during
suspend ?

I will test the above diff tomorrow, unless you have any other (better)
idea on how to deal with the problem.

cheers

-- 
balbi
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