From 750912fa366312e9c5bc83eab352898a26750401 Mon Sep 17 00:00:00 2001 From: David Sharp Date: Wed, 8 Dec 2010 13:46:47 -0800 Subject: tracing: Add an 'overwrite' trace_option. Add an "overwrite" trace_option for ftrace to control whether the buffer should be overwritten on overflow or not. The default remains to overwrite old events when the buffer is full. This patch adds the option to instead discard newest events when the buffer is full. This is useful to get a snapshot of traces just after enabling traces. Dropping the current event is also a simpler code path. Signed-off-by: David Sharp LKML-Reference: <1291844807-15481-1-git-send-email-dhsharp@google.com> Signed-off-by: Steven Rostedt --- Documentation/trace/ftrace.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation/trace') diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 67f1cc47325..1ebc24cf9a5 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -454,6 +454,11 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6] latencies, as described in "Latency trace format". + overwrite - This controls what happens when the trace buffer is + full. If "1" (default), the oldest events are + discarded and overwritten. If "0", then the newest + events are discarded. + ftrace_enabled -------------- -- cgit v1.2.3-18-g5258