trouble locating code that increments jiffies (arm)

trouble locating code that increments jiffies (arm)

[chris at basementcode.com]

 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.

 Thanks,
 -C

trouble locating code that increments jiffies (arm)

[Dave Hylands]

Hi Chris,

On Wed, May 11, 2011 at 6:22 AM,  <chris@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