To: perfctr-devel@lists.sourceforge.net, perfapi-devel@nacse.org
Subject: perfctr-2.0 released (finally!)

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

The most important change since 2.0-pre6 is that interrupt-mode
virtual perfctrs now work again.

There are also some API changes due to internal data-structure
rearrangements and cleanups. These were originally part of an
attempt to optimise cache-line usage. That didn't give any
improvements in my testing, but I kept the core changes as they
lead to a cleaner API.

Since so many people seem unwilling to use standard kernels as
opposed to vendor-hacked kernels, I now include a kernel patch
for the 2.4.3-12 (update) RedHat 7.1 kernel.

Version 2.0, 2001-08-08
- Resurrected partial support for interrupt-mode virtual perfctrs.
  virtual.c permits a single i-mode perfctr, in addition to TSC
  and a number of a-mode perfctrs. BUG: The i-mode PMC must be last,
  which constrains CPUs like the P6 where we currently restrict
  the pmc_map[] to be the identity mapping. (Not a problem for
  K7 since it is symmetric, or P4 since it is expected to use a
  non-identity pmc_map[].)
- Bug fix in perfctr_cpu_update_control(), to prevent a failed attempt
  to update the control from leaving the object in an inconsistent state.

Version 2.0-pre7, 2001-08-07
- Updated user-space library:
  * Coding tweaks to attempt to make gcc (various versions) generate
    better code. (Not entirely successful. May have to resort to
    hand-written assembly code.)
  * New vperfctr_read_ctrs() sampling procedure.
  * New perfctr_print_info() helper procedure.
- Updated example applications:
  * Use the library's perfctr_print_info() for consistent output.
  * Counts are now printed in decimal, not hex.
  * 'perfex' now checks for data layout mismatch when the child
    process' virtual perfctr is mmap:ed into user space.
  * 'self' uses the new vperfctr_read_ctrs() sampling procedure.
  * 'signal' compiles again.
- Cleaned up the driver's debugging code.
- Internal driver rearrangements. The low-level driver (x86) now handles
  sampling/suspending/resuming counters. Merged counter state (sums and
  start values) and CPU control data to a single "CPU state" object.
  This simplifies the high-level drivers, and permits some optimisations
  in the low-level driver by avoiding the need to buffer tsc/pmc samples
  in memory before updating the accumulated sums (not yet implemented).
- Removed WinChip "fake TSC" support. The user-space library can now
  sample with slightly less overhead on sane processors.

/ Mikael Pettersson