* trouble locating code that increments jiffies (arm)
@ 2011-05-11 13:22 chris at basementcode.com
2011-05-11 19:13 ` Dave Hylands
0 siblings, 1 reply; 2+ messages in thread
From: chris at basementcode.com @ 2011-05-11 13:22 UTC (permalink / raw)
To: kernelnewbies
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* trouble locating code that increments jiffies (arm)
2011-05-11 13:22 trouble locating code that increments jiffies (arm) chris at basementcode.com
@ 2011-05-11 19:13 ` Dave Hylands
0 siblings, 0 replies; 2+ messages in thread
From: Dave Hylands @ 2011-05-11 19:13 UTC (permalink / raw)
To: kernelnewbies
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
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2011-05-11 13:22 trouble locating code that increments jiffies (arm) chris at basementcode.com
2011-05-11 19:13 ` Dave Hylands
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