[PATCH] perf events: remove 64bit alignment padding from perf_event_context

[PATCH] perf events: remove 64bit alignment padding from perf_event_context

[Richard Kennedy]

Reorder perf_event_context to remove 8 bytes of 64 bit alignment padding
shrinking its size to 192 bytes, allowing it to fit into a smaller slab
and use one fewer cache lines.


Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>

---

patch against v3.0-rc2
compiled & tested on x86_64

regards
Richard


diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3412684..9d5b3d5 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -919,8 +919,8 @@ struct perf_event_context {
 	u64				parent_gen;
 	u64				generation;
 	int				pin_count;
-	struct rcu_head			rcu_head;
 	int				nr_cgroups; /* cgroup events present */
+	struct rcu_head			rcu_head;
 };
 
 /*

Re: [PATCH] perf events: remove 64bit alignment padding from perf_event_context

[Peter Zijlstra]

On Tue, 2011-06-07 at 16:33 +0100, Richard Kennedy wrote:
> Reorder perf_event_context to remove 8 bytes of 64 bit alignment padding
> shrinking its size to 192 bytes, allowing it to fit into a smaller slab
> and use one fewer cache lines.
> 
> 
> Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>

Nice, thanks!

[tip:perf/core] perf: Remove 64-bit alignment padding from perf_event_context

[tip-bot for Richard Kennedy]

Commit-ID:  28009ce4a8130af7260a9271901b4419834ad152
Gitweb:     http://git.kernel.org/tip/28009ce4a8130af7260a9271901b4419834ad152
Author:     Richard Kennedy <richard@rsk.demon.co.uk>
AuthorDate: Tue, 7 Jun 2011 16:33:38 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 1 Jul 2011 11:06:32 +0200

perf: Remove 64-bit alignment padding from perf_event_context

Reorder perf_event_context to remove 8 bytes of 64 bit alignment padding
shrinking its size to 192 bytes, allowing it to fit into a smaller slab
and use one fewer cache lines.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1307460819.1950.5.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 e76a410..2f7b5d4 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -894,8 +894,8 @@ struct perf_event_context {
 	u64				parent_gen;
 	u64				generation;
 	int				pin_count;
-	struct rcu_head			rcu_head;
 	int				nr_cgroups; /* cgroup events present */
+	struct rcu_head			rcu_head;
 };
 
 /*