Hi all,
Just to complete the info. I have repeated a similar test (SMP and
scaling frequency disabled in the BIOS, TSC clock) with another function:
If I measure the attached function with CLOCK_THREAD_CPUTIME_ID, I keep
getting variable timing results. The execution of this function takes
about 400 usecs in my system. Having called it more than 10_000 times,
most of the measures are within 100 usecs from this value. This range
makes sense to me. But I have found a few measures (less than 10 out of
10_000) which are over 1100 usecs, which it's a bit suspicious. Since
this clock just takes the execution time associated to a single thread
(no preemption time should be included) and the function's execution
time could be considered as "constant", it seems that something is going
wrong with this kind of clock.
Any idea?
Thanks
Hector
PS: Ubuntu 2.6.24.-25-rt is based on 2.6.24.7-rt27 patch (link
<http://packages.ubuntu.com/hardy-updates/linux-restricted-modules-2.6.24-25-rt>)
void make_job ()
{
long temp = 0;
int index, index2 = 0;
for (index = 0; index < 5000; index ++) {
temp += index;
if (index%97 == 0) {
for (index2 = 0; index2 < 1000; index2 ++) {
temp +=index;
}
}
}
}
Uwe Kleine-König escribió:
On Tue, Dec 01, 2009 at 10:32:28AM -0200, Luis Claudio R. Goncalves wrote:
Along with that, the latest version for 2.6.24, IIRC, was 2.6.24.7-rt27.
So, it sounds like you are using older versions of old software.
The version scheme of Ubuntu doesn't allow to read the used rt patch
from the kernel version. The Ubuntu version used is 2.6.24-25-rt. This
only means something like: The 25th Ubuntu revision of the 2.6.24
kernel in the rt feature set.
Best regards
Uwe
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
