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>
diff --git a/arch/Kconfig b/arch/Kconfig
index 99193b1..beea3cc 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -30,6 +30,18 @@
If unsure, say N.
+config OPROFILE_EVENT_MULTIPLEX
+ bool "OProfile multiplexing support (EXPERIMENTAL)"
+ default n
+ depends on OPROFILE && X86
+ help
+ 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.
+
+ If unsure, say N.
+
config HAVE_OPROFILE
bool