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Re: [PATCH 0/2] Alchemy: fix interrupt routing

To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH 0/2] Alchemy: fix interrupt routing
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 5 Dec 2007 19:12:08 +0000
Cc: Manuel Lauss <manuel.lauss@fh-hagenberg.at>, linux-mips@linux-mips.org
In-reply-to: <4756F494.8090207@ru.mvista.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <200712051908.18780.sshtylyov@ru.mvista.com> <4756D42E.9040609@fh-hagenberg.at> <20071205182353.GC10697@linux-mips.org> <4756F494.8090207@ru.mvista.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.17 (2007-11-01)
On Wed, Dec 05, 2007 at 09:57:24PM +0300, Sergei Shtylyov wrote:

>    It works:

> 41 total events, 5.109 events/sec

That's the expected behaviour, good.

One of the remaining problems on some platforms with tickless kernels is
that not all clocksource / clockevent driver combinations are playing
nicely with each other.  You can switch the clocksource driver manually
at runtime.  First let's see what clocksource we have:

  # cd /sys/devices/system/clocksource/clocksource0/
  # cat available_clocksource 
  MIPS pit jiffies 
  # cat current_clocksource 
  MIPS 

MIPS is the CP0 count register.  pit is the i8259 and jiffies simply counts
interrupts like in the old days so has problems with lost timer interrupts
and generally not such a great idea for tickless.  You should be able to
switch between all these drivers by something like:

  # echo jiffies > current_clocksource
  Time: jiffies clocksource has been installed.
  #

Try switching between all the available clocksources a few times to see if
that's working right also.

   Ralf

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