linux-kernel - Re: [tip:timers/urgent] tick: Fix oneshot broadcast setup really

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Message-ID: <87lils3t3q.fsf@turtle.gmx.de>
Date:	Thu, 19 Apr 2012 12:37:29 +0200
From:	Sven Joachim <svenjoac@....de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>, mingo@...nel.org,
	hpa@...or.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, rjw@...k.pl,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:timers/urgent] tick: Fix oneshot broadcast setup really

Am 19.04.2012 um 10:29 schrieb Thomas Gleixner:

> On Wed, 18 Apr 2012, Suresh Siddha wrote:
>> On Wed, 2012-04-18 at 17:31 +0200, Thomas Gleixner wrote:
>> From: Suresh Siddha <suresh.b.siddha@...el.com>
>> Subject: tick: Fix the spurious broadcast timer ticks
>> 
>> During resume, tick_resume_broadcast() programs the broadcast timer
>> in oneshot mode unconditionally. On the platforms where broadcast timer
>> is not really required, this will generate spurious broadcast timer ticks
>> upon resume. For example, on the always running apic timer platforms with
>> HPET, I see spurious hpet tick once every ~5minutes (which is the 32-bit
>> hpet counter wraparound time).
>> 
>> Similar to boot time, during resume make the oneshot mode setting of
>> the broadcast clock event device conditional on the state of active broadcast
>> users. 
>> 
>> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
>
> Sven, Santosh, can you confirm that this works for you on top of the
> other two patches?

Works for me, thanks.

>> ---
>>  kernel/time/tick-broadcast.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>> 
>> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
>> index bf57abd..766cd82 100644
>> --- a/kernel/time/tick-broadcast.c
>> +++ b/kernel/time/tick-broadcast.c
>> @@ -346,7 +346,8 @@ int tick_resume_broadcast(void)
>>  						     tick_get_broadcast_mask());
>>  			break;
>>  		case TICKDEV_MODE_ONESHOT:
>> -			broadcast = tick_resume_broadcast_oneshot(bc);
>> +			if (!cpumask_empty(tick_get_broadcast_mask()))
>> +				broadcast = tick_resume_broadcast_oneshot(bc);
>>  			break;
>>  		}
>>  	}

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