[tip:tracing/core] tracing/events: change the type of __str_loc_item to unsigned short

[tip-bot for Li Zefan]

Commit-ID:  b0aae68cc5508f3c2fbf728988c954db4c8b8a53
Gitweb:     http://git.kernel.org/tip/b0aae68cc5508f3c2fbf728988c954db4c8b8a53
Author:     Li Zefan <lizf@xxxxxxxxxxxxxx>
AuthorDate: Thu, 21 May 2009 13:59:18 +0800
Committer:  Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Tue, 26 May 2009 00:15:21 +0200

tracing/events: change the type of __str_loc_item to unsigned short

When defining a dynamic size string, we add __str_loc_##item to the
trace entry, and it stores the location of the actual string in
entry->_str_data[]

'unsigned short' should be sufficient to store this information, thus
we save 2 bytes per dyn-size string in the ring buffer.

[ Impact: reduce memory occupied by dyn-size strings in ring buffer ]

Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
LKML-Reference: <4A14EDB6.2050507@xxxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>


---
 include/trace/ftrace.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index edb02bc..b5ff2e8 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -25,7 +25,7 @@
 #define __field(type, item)		type	item;
 
 #undef __string
-#define __string(item, src)		int	__str_loc_##item;
+#define __string(item, src)		unsigned short	__str_loc_##item;
 
 #undef TP_STRUCT__entry
 #define TP_STRUCT__entry(args...) args
--
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