On Tue, 27 Jul 2010, John Baldwin wrote:

On Tuesday, July 27, 2010 8:43:00 am pluknet wrote:

What is a status of "options PERFMON" on amd64?
Looking at cvs I see amd64/include/perfmon.h was never here.

PERFMON in general is obsoleted by hwpmc(4) which is far more useful and
featureful.  It should probably just be axed.

Nothing should just be axed.

hwpmc(4) is far too featureful for me, yet perfmon(4) still does things
for me that hwpmc cannot do:
- from userland, without using the library, try undocumented unnamed
  counters.  There are a few useful ones for k7.  E.g.:
    0xc8 (k8-fr-retired-near-returns) and
    0xc9 (k8-fr-retired-near-returns-mispredicted)
  are k8-only according to hwpmc and amd docs, but also work on my k7
  (after a 4-line fix for perfmon on kx).
- in the kernel count, events at the level of individual functions, non-
  statistically using high resolution kernel profiling.  This may result
  in more time spent counting than doing useful work, but provides
  high resolution.

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