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Subject[tip:tracing/core] tracing/events: change the type of __str_loc_item to unsigned short
Commit-ID:  b0aae68cc5508f3c2fbf728988c954db4c8b8a53
Gitweb: http://git.kernel.org/tip/b0aae68cc5508f3c2fbf728988c954db4c8b8a53
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Thu, 21 May 2009 13:59:18 +0800
Committer: Frederic Weisbecker <fweisbec@gmail.com>
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@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A14EDB6.2050507@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>


---
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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