To: perfctr-devel@lists.sourceforge.net
Subject: perfctr-2.0-pre6 released

perfctr-2.0-pre6 is now available at the usual place:
<http://www.csd.uu.se/~mikpe/linux/perfctr/>.

This version has three important bug fixes, and updated
patches for kernels 2.4.7/2.4.7-ac1.

I'm going to take one last(?) look at data layout and cache-line
usage in critical paths. Unless I can find any clear improvements,
this version will become perfctr-2.0 final sometime next week.

Version 2.0-pre6, 2001-07-27
- Sampling bug fix for SMP. Normally processes are suspended and
  resumed many times per second, but on SMP machines it is possible
  for a process to run for a long time without being suspended.
  Since sampling is performed at the suspend and resume actions,
  a performance counter may wrap around more than once between
  sampling points. When this occurs, the accumulated counts will
  be highly variable and much lower than expected.
  A software timer is now used to ensure that sampling deadlines
  aren't missed on SMP machines.
- Bug fix in the x86 "redirect call" backpatching routine.
- Bug fix in the internal debugging code (CONFIG_PERFCTR_DEBUG).
- Minor performance tweak for the P5/P5MMX read counters procedures.
- To avoid undetected data layout mismatches, the user-space library
  now checks the data layout version field in a virtual perfctr when
  it is being mmap:ed into the user's address space.

/ Mikael Pettersson