trouble locating code that increments jiffies (arm)

Dave Hylands dhylands at gmail.com
Wed May 11 15:13:21 EDT 2011


Hi Chris,

On Wed, May 11, 2011 at 6:22 AM,  <chris at basementcode.com> wrote:
>  Hi list,
>
>  I've been looking for the code that increments the jiffies variable as
>  well as the code that connects a timer interrupt to the function that
>  increments the variable. I'm working with the ARM architecture in case
>  that makes a difference. I was also wondering, how many jiffies are
>  there? Right now I'm finding that if I disable the local timer for the
>  boot CPU (during boot) the jiffies variable stop incrementing. I always
>  assumed the global timer was supposed to increment a single jiffies
>  variable. I'm working with an old, modified, version of QEMU so I'm
>  leaning towards a QEMU bug for this problem.

It's updated here:
<http://lxr.linux.no/linux+v2.6.38/kernel/timer.c#L1304>

The machine description has a .timer entry, which points to a timer
initialization function. We use clock events, so it gets tied in
through there.

Sorry for being vague - I'm only mildly familiar with that particular code.

There is some documentation and background over here:
<http://lxr.linux.no/linux+v2.6.38/Documentation/timers/highres.txt>

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com



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