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authorSteven Rostedt <srostedt@redhat.com>2009-04-15 16:53:47 -0400
committerIngo Molnar <mingo@elte.hu>2009-04-17 17:03:28 +0200
commitd1b182a8d49ed6416325b4e0a1cb0f17cd4e702a (patch)
treef482bfba39828503f32ed994829d2d3cd6b81bfe /include/linux/ring_buffer.h
parente6187007d6c365b551c69ea3df46f06fd1c8bd19 (diff)
tracing/events/ring-buffer: expose format of ring buffer headers to users
Currently, every thing needed to read the binary output from the ring buffers is available, with the exception of the way the ring buffers handles itself internally. This patch creates two special files in the debugfs/tracing/events directory: # cat /debug/tracing/events/header_page field: u64 timestamp; offset:0; size:8; field: local_t commit; offset:8; size:8; field: char data; offset:16; size:4080; # cat /debug/tracing/events/header_event type : 2 bits len : 3 bits time_delta : 27 bits array : 32 bits padding : type == 0 time_extend : type == 1 data : type == 3 This is to allow a userspace app to see if the ring buffer format changes or not. [ Impact: allow userspace apps to know of ringbuffer format changes ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ring_buffer.h')
-rw-r--r--include/linux/ring_buffer.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index f0aa486d131..fac8f1ac6f4 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -166,6 +166,11 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
size_t len, int cpu, int full);
+struct trace_seq;
+
+int ring_buffer_print_entry_header(struct trace_seq *s);
+int ring_buffer_print_page_header(struct trace_seq *s);
+
enum ring_buffer_flags {
RB_FL_OVERWRITE = 1 << 0,
};