tree c9003cd927ed878412e89a59db0138b6b701b629
parent 6e63ea4b0b14ff5fb8a3ca704fcda7d28b95f079
author Jason Yeh <jason.yeh@amd.com> 1247053778 +0200
committer Robert Richter <robert.richter@amd.com> 1248100433 +0200

oprofile: Implement performance counter multiplexing

The number of hardware counters is limited. The multiplexing feature
enables OProfile to gather more events than counters are provided by
the hardware. This is realized by switching between events at an user
specified time interval.

A new file (/dev/oprofile/time_slice) is added for the user to specify
the timer interval in ms. If the number of events to profile is higher
than the number of hardware counters available, the patch will
schedule a work queue that switches the event counter and re-writes
the different sets of values into it. The switching mechanism needs to
be implemented for each architecture to support multiplexing. This
patch only implements AMD CPU support, but multiplexing can be easily
extended for other models and architectures.

There are follow-on patches that rework parts of this patch.

Signed-off-by: Jason Yeh <jason.yeh@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>