From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Date: Wed, 15 Mar 2006 14:34:41 +0100
Subject: Re: [Xenomai-core] Synchronising TSC and periodic timer
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Jan Kiszka wrote:
 > Likely too simple: The periodic IRQ seems to pop up on every CPU so that
 > the TSC could be recorded, but will this happen synchronously? At least
 > we will see (IRQ) jitters, and those jitters could already create in the
 > single-CPU case a non-monotonic clock...

I do not know how this issue is solved in Linux, but there seem to be a
simple solution: before adding the tsc offset to the last tick time,
this tsc offset should be compared with the tick duration in tsc
counts; if it is greater, then replace with the tick duration in tsc.

-- 


					    Gilles Chanteperdrix.