[PATCH 3/3] perf: Limit callchains to 127

[Arun Sharma]

Stack depth of 255 seems excessive, given that copy_from_user_nmi()
could be slow.

Signed-off-by: Arun Sharma <asharma@xxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 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 ddbb6a9..d1e71c1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -609,7 +609,7 @@ struct perf_guest_info_callbacks {
 #include <linux/sysfs.h>
 #include <asm/local.h>
 
-#define PERF_MAX_STACK_DEPTH		255
+#define PERF_MAX_STACK_DEPTH		127
 
 struct perf_callchain_entry {
 	__u64				nr;
-- 
1.7.8.4

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