[tip:perf/core] perf/core: Add a flag for partial AUX records

[tip-bot for Alexander Shishkin <tipbot@zytor.com>]

Commit-ID:  ae0c2d995d648d5165545d5e05e2869642009b38
Gitweb:     http://git.kernel.org/tip/ae0c2d995d648d5165545d5e05e2869642009b38
Author:     Alexander Shishkin <alexander.shishkin@linux.intel.com>
AuthorDate: Mon, 20 Feb 2017 15:33:51 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 16 Mar 2017 09:51:11 +0100

perf/core: Add a flag for partial AUX records

The Intel PT driver needs to be able to communicate partial AUX transactions,
that is, transactions with gaps in data for reasons other than no room
left in the buffer (i.e. truncated transactions). Therefore, this condition
does not imply a wakeup for the consumer.

To this end, add a new "partial" AUX flag.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20170220133352.17995-4-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/uapi/linux/perf_event.h | 1 +
 kernel/events/ring_buffer.c     | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index bec0aad..d09a9cd 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -915,6 +915,7 @@ enum perf_callchain_context {
  */
 #define PERF_AUX_FLAG_TRUNCATED		0x01	/* record was truncated to fit */
 #define PERF_AUX_FLAG_OVERWRITE		0x02	/* snapshot from overwrite mode */
+#define PERF_AUX_FLAG_PARTIAL		0x04	/* record contains gaps */
 
 #define PERF_FLAG_FD_NO_GROUP		(1UL << 0)
 #define PERF_FLAG_FD_OUTPUT		(1UL << 1)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 9654e55..2831480 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -424,8 +424,8 @@ err:
  */
 void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
 {
+	bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED);
 	struct ring_buffer *rb = handle->rb;
-	bool wakeup = !!handle->aux_flags;
 	unsigned long aux_head;
 
 	/* in overwrite mode, driver provides aux_head via handle */