perf data: Document directory format header: HEADER_DIR_FORMAT

We forgot to update the perf.data file format document for the
HEADER_DIR_FORMAT header, do it now from comments in the patch
introducing it.

Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Alexey Budankov <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Chong Jiang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Simon Que <[email protected]>
Fixes: 258031c017c3 ("perf header: Add DIR_FORMAT feature to describe directory data")
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index 600999f89c6d..6375e6fb8bac 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -302,6 +302,23 @@ One uint64_t for the clockid frequency, specified, for instance, via 'perf
 record -k' (see clock_gettime()), to enable timestamps derived metrics
 conversion into wall clock time on the reporting stage.
 
+	HEADER_DIR_FORMAT = 24,
+
+The data files layout is described by HEADER_DIR_FORMAT feature.  Currently it
+holds only version number (1):
+
+  uint64_t version;
+
+The current version holds only version value (1) means that data files:
+
+- Follow the 'data.*' name format.
+
+- Contain raw events data in standard perf format as read from kernel (and need
+  to be sorted)
+
+Future versions are expected to describe different data files layout according
+to special needs.
+
         HEADER_BPF_PROG_INFO = 25,
 
 struct bpf_prog_info_linear, which contains detailed information about