[PATCH] blktrace: add timestamp message

This adds a new timestamp message to blktrace, giving the timeofday when
we starting tracing. This helps user space correlate block trace events
with eg an application strace.

This requires a (compatible) update to blkparse. The changed blkparse
is still able to process traces generated by older kernels, and older
versions of blkparse should silently ignore the new records (because
they have a pid of 0).

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index b99a714fcac..3680ff9a30e 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -50,6 +50,15 @@ enum blktrace_act {
 };
 
 /*
+ * Notify events.
+ */
+enum blktrace_notify {
+        __BLK_TN_PROCESS = 0,           /* establish pid/name mapping */
+        __BLK_TN_TIMESTAMP,             /* include system clock */
+};
+
+
+/*
  * Trace actions in full. Additionally, read or write is masked
  */
 #define BLK_TA_QUEUE            (__BLK_TA_QUEUE | BLK_TC_ACT(BLK_TC_QUEUE))
@@ -68,6 +77,9 @@ enum blktrace_act {
 #define BLK_TA_BOUNCE           (__BLK_TA_BOUNCE)
 #define BLK_TA_REMAP            (__BLK_TA_REMAP | BLK_TC_ACT(BLK_TC_QUEUE))
 
+#define BLK_TN_PROCESS          (__BLK_TN_PROCESS | BLK_TC_ACT(BLK_TC_NOTIFY))
+#define BLK_TN_TIMESTAMP        (__BLK_TN_TIMESTAMP | BLK_TC_ACT(BLK_TC_NOTIFY))
+
 #define BLK_IO_TRACE_MAGIC      0x65617400
 #define BLK_IO_TRACE_VERSION    0x07