probe hrtimer testing

[William Cohen]

Stone, Joshua I wrote:
> On Tuesday, May 23, 2006 10:57 AM, William Cohen wrote:
> 
>>Looking over the test coverage results recently posted, one of the
>>places that is lacking in testing is the probes for hrtimer. Josh,
>>does anyone have some tests for that area of the translator? It would
>>do a lot to improve the test coverage of tapsets.cxx.
> 
> 
> The hrtimer is not tested because it's not complete.  I ran into a
> problem with needing exported symbols from the kernel, and LKML rejected
> my request.  So until support is added to the kernel ABI for using
> hrtimers, the code I added will be unusable.
> 
> I checked it in as part of normal development, in hopes that the ABI
> would get resolved.  Since hrtimers are still not exported, perhaps I
> should remove the code.  Would it be sufficient for your coverage tests
> if I just blocked out the code with "#ifdef ENABLE_HRTIMER"?

I wouldn't bother with the #ifdef.

> If anyone has an interest in seeing the hrtimers work in SystemTap,
> please speak up.  If there's enough interest, then maybe we can go back
> to LKML to try to get it enabled in the ABI.
> 
> 
> Josh

In the 2.6.17-rc4 kernel it looks like hrtimer is used by 
kernel/itimer.c. Is there a particular benefit explicitly using the 
hrtimer rather than going through the normal timer mechanism? Are there 
other modules that could use the hrtimer directly?

-Will