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>

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index bec0aad0e15cd3798f6858038d661b1b1ce1b3bc..d09a9cd021b1230730d23eefd0c149df51852c93 100644 (file)
--- 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 9654e55c38d6dbba7af8db7100a0a9919b498a9e..2831480c63a28b8e9b8cee1c0b30968860b3fcd0 100644 (file)
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -424,8 +424,8 @@ void *perf_aux_output_begin(struct perf_output_handle *handle,
  */
 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 */