Re: At a loss: Kernel 2.6.19-rt15 with ixp425

[Sven-Thorsten Dietrich <thebigcorporation@gmail.com>]

On Tue, 2010-06-08 at 12:17 -0600, Eric W Anderson wrote:
> Hello All,

Hi Eric,

2.6.19 is very very old.

What is preventing you from a Kernel upgrade?

Sven


> 
> I can't figure out (or haven't figured out) how to get actual high-resolution
> timers on the above platform.  I'm kind of stuck with 2.6.19, unfortunately.
> I've applied the -rt patch to stock 2.6.19, merged in some random patches to
> support my hardware, and gotten it to boot. But, here's what confuses me:  I
> have the hrtimer API, but my actual clock resolution is still shown as  10ms.
> 
>   root@patty:/# cat /proc/timer_list 
>   Timer List Version: v0.1
>   HRTIMER_MAX_CLOCK_BASES: 2
>   now at 2766685920305 nsecs
>   
>   cpu: 0
>    clock 0:
>     .index:      0
>     .resolution: 10000000 nsecs
>     .get_time:   ktime_get_real
>   active timers:
>    clock 1:
>     .index:      1
>     .resolution: 10000000 nsecs
>     .get_time:   ktime_get
>   active timers:
>    #0: <c4615ec8>, hrtimer_wakeup
>    # expires at 2766802147358 nsecs [in 116227053 nsecs]
>    #1: <c4615ec8>, it_real_fn
>    # expires at 2767494816966 nsecs [in 808896661 nsecs]
>    #2: <c4615ec8>, it_real_fn
>    # expires at 3642163204498 nsecs [in 875477284193 nsecs]
>    #3: <c4615ec8>, it_real_fn
>    # expires at 3643403169278 nsecs [in 876717248973 nsecs]
> 
> Additionally, I don't see CONFIG_HIGH_RES_TIMERS anywhere in my kernel
> menuconfig.  I've added a patch from Kevin Hilman and Milan Svoboda
> (http://lkml.indiana.edu/hypermail/linux/kernel/0607.1/2343.html) which
> purports to enable a high-resolution clock event source for this board, but
> that doesn't seem to change anything. 
> 
> I think I don't properly understand the preempt_rt / hrtimers /
> board-specific-bits ecosystem here.  What are the bits and pieces I need in
> order to have high-resolution timers on this platform?
> 
> Many, many thanks,
> Eric Anderson
> 
>