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From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Con Kolivas <kernel@kolivas.org>
Cc: tony@atomide.com, tuukka.tikkanen@elektrobit.com, akpm@osdl.org,
	johnstul@us.ibm.com, linux-kernel@vger.kernel.org, ak@muc.de,
	george@mvista.com
Subject: Re: [ck] [PATCH] dynamic-tick patch modified for SMP
Date: Tue, 16 Aug 2005 18:49:42 +0530	[thread overview]
Message-ID: <20050816131942.GD8608@in.ibm.com> (raw)
In-Reply-To: <200508160230.52860.kernel@kolivas.org>

On Tue, Aug 16, 2005 at 02:30:51AM +1000, Con Kolivas wrote:
> Time definitely was lost the longer the machine was running.

I think I found the reason for time drift. Basically cur_timer->mark_offset
doesnt expect to be called from non-timer interrupt handler. Hence it drops
one jiffy from the lost count. I fixed this in some "crude" fashion and time
has not drifted so far or is pretty much close to what it was in pre-smp 
version.  Will find a neat way to fix this and post a patch soon.

> You mean disable it at runtime or not compile it in at all? Disabling it at 
> runtime caused what I described to you as PIT mode (long stalls etc).

I think I have recreated this on a machine here. Disabling 
CONFIG_DYN_TICK_APIC at compile-time didnt seem to make any difference. Will 
look at this problem next.


-- 


Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017

  reply	other threads:[~2005-08-16 13:20 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-12 20:19 [PATCH] dynamic-tick patch modified for SMP Srivatsa Vaddagiri
2005-08-13  1:35 ` [ck] " Con Kolivas
2005-08-13  6:51   ` Con Kolivas
2005-08-13 11:37     ` Srivatsa Vaddagiri
2005-08-13 14:53       ` Con Kolivas
2005-08-13 16:46         ` Srivatsa Vaddagiri
2005-08-14  0:18           ` Con Kolivas
2005-08-14  4:15             ` Kyle Moffett
2005-08-15 15:47               ` Srivatsa Vaddagiri
2005-08-15 16:39                 ` john stultz
2005-08-16  2:11                   ` Srivatsa Vaddagiri
2005-08-15 15:35             ` Srivatsa Vaddagiri
2005-08-15 16:30               ` Con Kolivas
2005-08-16 13:19                 ` Srivatsa Vaddagiri [this message]
2005-08-16 13:23                   ` Con Kolivas
2005-08-17  7:53                     ` Tony Lindgren

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