[PATCH] trace: reorder perf_event_context to remove alignment padding on 64 bit builds

[PATCH] trace: reorder perf_event_context to remove alignment padding on 64 bit builds

[Richard Kennedy]

Remove 8 bytes of alignment padding from perf_event_context on 64 bit
builds which shrinks its size to 192 bytes allowing it to fit into one
fewer cache lines and into a smaller slab.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
---
patch against v2.6.38-rc7
compiled and tested on x86_64

regards
Richard



diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index dda5b0a..59792fe 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -846,8 +846,8 @@ enum perf_event_context_type {
  * Used as a container for task events and CPU events as well:
  */
 struct perf_event_context {
-	enum perf_event_context_type	type;
 	struct pmu			*pmu;
+	enum perf_event_context_type	type;
 	/*
 	 * Protect the states of the events in the list,
 	 * nr_active, and the list:

[tip:perf/urgent] perf: Reorder & optimize perf_event_context to remove alignment padding on 64 bit builds

[tip-bot for Richard Kennedy]

Commit-ID:  ee643c4179c3a18b018de3a4c07a7bb3a75c8e4e
Gitweb:     http://git.kernel.org/tip/ee643c4179c3a18b018de3a4c07a7bb3a75c8e4e
Author:     Richard Kennedy <richard@rsk.demon.co.uk>
AuthorDate: Mon, 7 Mar 2011 15:46:59 +0000
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 16 Mar 2011 14:04:14 +0100

perf: Reorder & optimize perf_event_context to remove alignment padding on 64 bit builds

Remove 8 bytes of alignment padding from perf_event_context on 64 bit
builds which shrinks its size to 192 bytes allowing it to fit into one
fewer cache lines and into a smaller slab.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1299512819.2039.5.camel@castor.rsk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/linux/perf_event.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 614615b..f495c01 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -878,8 +878,8 @@ enum perf_event_context_type {
  * Used as a container for task events and CPU events as well:
  */
 struct perf_event_context {
-	enum perf_event_context_type	type;
 	struct pmu			*pmu;
+	enum perf_event_context_type	type;
 	/*
 	 * Protect the states of the events in the list,
 	 * nr_active, and the list: