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authorMike Frysinger <vapier@gentoo.org>2009-06-12 13:17:43 -0400
committerIngo Molnar <mingo@elte.hu>2009-06-12 19:37:30 +0200
commit018df72dd01576ab199c6129233cdeaf1409958b (patch)
tree1561017056cc1289e373b094d72ba41a4382308b
parent974802eaa1afdc87e00821df7020a2b3c6fee623 (diff)
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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: Mike 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: Ingo Molnar <mingo@elte.hu>
-rw-r--r--init/Kconfig2
-rw-r--r--tools/perf/design.txt15
2 files changed, 17 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index c649657e225..d3a50967c33 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -936,6 +936,8 @@ config AIO
config HAVE_PERF_COUNTERS
bool
+ help
+ See tools/perf/design.txt for details.
menu "Performance Counters"
diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index 860e116d979..f71e0d245cb 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -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.