Robust Futexes status

From: david singleton
Date: Sun Oct 23 2005 - 15:52:18 EST



Inaky Perez-Gonzalez has a wonderful suite of performance, stress and
functionality tests for the fusyn pthreads mutex package.

I've been able to use this test suite to measure robust futex performance with very little
change. The posix test suite compiles cleanly against the nptl header files and libararies,
which is very good news. It means we got the header files and libraries right.

The following are three graphs on the pthread mutex ownership change latency test
for all three flavors of kernel, PREEMPT_NONE, PREEMPT_DESKTOP and PREEMPT_RT,
using the realtime preemption patch-2.6.14-rc5-rt5. The ownership_change_latency
test ran unchanged, modulo changing the clock-id for the real time clock in the run script.

The graphs are just to show relative performance for the different flavor kernels. The
kernel's perform quite closely regardless of the 'flavor' of kernel. The kernels have quite a few
debugging options turned so I can look for any problems so performance is not optimal.

It appears the robust futex functionality is healthy in all flavors of kernel.



David

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