tlug: Timing in Linux and 686 Cache

[Manuel Chakravarty <chak@example.com>]

Hi!

I have two probably not easy to answer questions:

* Does anybody have an idea whether it is possible in Linux to time the
  execution of user-level code below a resolution of 10ms?  Using the function
  `getrusage', a resolution of 10ms is the best that I can get.  Is there
  anything better?

* Is there a OS function that lets me invalidate the data cache of the
  processor?  If not, does anybody know which `asm' section achieves this
  effect for a MMX Pentium Pro?

For the curious: We are trying to time some cache effects on a Pentium Pro
machine.  With a resolution of 10ms, we have to use a loop, repeating the test
to measure the accumulated runtime.  Without invalidating the cache at the
beginning of the loop, the results are probably distorted.

Thanks for any tips!

Manuel
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