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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

init/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -936,6 +936,8 @@ config AIO 


config HAVE_PERF_COUNTERS

	bool

	help

	  See tools/perf/design.txt for details.



menu "Performance Counters"

tools/perf/design.txt

+15 −0
Original line number Diff line number Diff line
@@ -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.