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From: Milan Svoboda <msvoboda@ra.rockwell.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: posix-timers overrun broken?
Date: Thu, 8 Feb 2007 08:55:01 +0100	[thread overview]
Message-ID: <OFB812AC35.7E514449-ONC125727C.0029AA85-C125727C.002B65DA@ra.rockwell.com> (raw)

> On Wed, 2007-02-07 at 14:36 +0100, Milan Svoboda wrote:
> > But if the next interrupt arrives before function collect_signal is 
called 
> > to actually deliver the
> > siginfo_t to userspace, the si.overrun is cleared in posix_timer_event 
and 
> > we have just forgotten
> > one overrun...
> > 
> > Am I wrong?
> 
> Yes. posix_timer_event() is only called when the timer expires the first
> time. When the signal has been queued, the timer is not rearmed and the
> overrun is calculated in the actual signal delivery path, which calls
> do_schedule_next_timer().

Ok understand.

So it seems to me that drivers/char/mmtimer.c is wrong. It is
driver to additional hardware timers and mmtimer exports them as a posix 
timer.
When interrupt happens, they call posix_timer_event and set hardware 
interrupt
to the next tick. I use the same practise in my driver and found
that overruns are reported wrongly.

How to plug "external" source of ticks to the posix timers?

As far as I know current HRT doesn't allow us to use more sources of
ticks together, only one is selected, correct?

Milan




             reply	other threads:[~2007-02-08  7:54 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-08  7:55 Milan Svoboda [this message]
  -- strict thread matches above, loose matches on Subject: below --
2007-02-07 13:36 Milan Svoboda
2007-02-07 16:14 ` Thomas Gleixner

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