Poor performance with POSIX threads

[Pedro Sevilla]

After migrating from a DCE-thread-based
application on HP-UX 10.20 to POSIX threads
on HP-UX 11.00, we've noticed a big
increase on CPU usage.

Is there any option to care about when
migrating from DCE to POSIX that could affect
performance?

We've used Quantify to look for problems and
a function from libc called ___kwakeup is
responsible for more than 70% of CPU time.
That seems to be related with mutexs. Do
they have a different behaviour when using
POSIX threads?

Thanks in advance for your answers.

[Steven Gillard_2 · Accepted solution]

The thing to remember about DCE threads is that they were user level threads, so your process could only use up to 100% of one CPU. On HPUX 11 you have kernel threads, which means different threads in your process can be running simultaneously on multiple CPU's. This can result in higher CPU utilisation if your application is being pushed hard enough. Is your application is performing better now or worse?

Regards,
Steve