Timer interrupt on Linux 3.0.3

Vineeth vneethv at gmail.com
Wed Sep 21 16:56:00 EST 2011


>> What was the issue?  You really should try to make this work rather than
>> hack around it.

what we found was the decrementer is not generating an exception when it
becomes 0. and the timebase registers are not getting incremented too. The
exceptions are enabled in MSR registers.

we are using embedded60x port of linux3.0.3; we've written the dts file with
proper clock-frequency/timebase-frequency values.

Do you think we might've missed some configuration in the timer perspective
?


On Fri, Sep 16, 2011 at 10:33 PM, Scott Wood <scottwood at freescale.com>wrote:

> On 09/16/2011 06:43 AM, Vineeth wrote:
> > Hi,
> >
> > We are porting Linux on MPC7410 based board. As there was some issue
> > with the processor DECrementer and timebase registers,
>
> What was the issue?  You really should try to make this work rather than
> hack around it.
>
> > lately we moved to Linux 3.0.3. What we found was even without a proper
> > timer, the kernel with initramfs worked (except the calls like
> > sleep,delay ofcourse); Is there any major difference in the scheduler ?
> > or the way context switch happens ? is it not depended on the timer
> > interrupt or the timer ??
>
> If your timer is broken then you won't get timeslice expiration, but
> basic scheduling should still work.  Most scheduling (depending on type
> of load, of course) will be triggered by processes blocking or being
> woken up by I/O, not timeslice expiration.
>
> -Scott
>
>
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