[PATCH] tracing/events: change the type of __str_loc_item to unsignedshort

[Li Zefan]

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>
---
 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
-- 1.5.4.rc3 
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