Commit 018df72d authored by Mike Frysinger's avatar Mike Frysinger Committed by Ingo Molnar
Browse files

perf_counter: Start documenting HAVE_PERF_COUNTERS requirements



Help out arch porters who want to support perf counters by listing some
basic requirements.
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1244827063-24046-1-git-send-email-vapier@gentoo.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 974802ea
......@@ -936,6 +936,8 @@ config AIO
config HAVE_PERF_COUNTERS
bool
help
See tools/perf/design.txt for details.
menu "Performance Counters"
......
......@@ -440,3 +440,18 @@ by this process or by another, and doesn't affect any counters that
this process has created on other processes. It only enables or
disables the group leaders, not any other members in the groups.
Arch requirements
-----------------
If your architecture does not have hardware performance metrics, you can
still use the generic software counters based on hrtimers for sampling.
So to start with, in order to add HAVE_PERF_COUNTERS to your Kconfig, you
will need at least this:
- asm/perf_counter.h - a basic stub will suffice at first
- support for atomic64 types (and associated helper functions)
- set_perf_counter_pending() implemented
If your architecture does have hardware capabilities, you can override the
weak stub hw_perf_counter_init() to register hardware counters.
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