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

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH 0/2] Alchemy: fix interrupt routing
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Wed, 05 Dec 2007 22:22:20 +0300
Cc: Manuel Lauss <manuel.lauss@fh-hagenberg.at>, linux-mips@linux-mips.org
In-reply-to: <20071205191208.GA12547@linux-mips.org>
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Ralf Baechle 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

   I only have MIPS and jiffies of course. :-)

# 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.

   It died after I selected jiffies.

   Ralf

WBR, Sergei

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