perf intel-pt: Add support for lookahead

Implement the lookahead callback to let the decoder access subsequent
buffers. intel_pt_lookahead() manages the buffer lifetime and calls the
decoder for each buffer until the decoder returns a non-zero value.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190604130017.31207-11-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 4a61c73..3e3a013 100644 (file)
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -278,7 +278,63 @@ static int intel_pt_get_buffer(struct intel_pt_queue *ptq,
        return 0;
 }
 
-/* This function assumes data is processed sequentially only */
+/* Do not drop buffers with references - refer intel_pt_get_trace() */
+static void intel_pt_lookahead_drop_buffer(struct intel_pt_queue *ptq,
+                                          struct auxtrace_buffer *buffer)
+{
+       if (!buffer || buffer == ptq->buffer || buffer == ptq->old_buffer)
+               return;
+
+       auxtrace_buffer__drop_data(buffer);
+}
+
+/* Must be serialized with respect to intel_pt_get_trace() */
+static int intel_pt_lookahead(void *data, intel_pt_lookahead_cb_t cb,
+                             void *cb_data)
+{
+       struct intel_pt_queue *ptq = data;
+       struct auxtrace_buffer *buffer = ptq->buffer;
+       struct auxtrace_buffer *old_buffer = ptq->old_buffer;
+       struct auxtrace_queue *queue;
+       int err = 0;
+
+       queue = &ptq->pt->queues.queue_array[ptq->queue_nr];
+
+       while (1) {
+               struct intel_pt_buffer b = { .len = 0 };
+
+               buffer = auxtrace_buffer__next(queue, buffer);
+               if (!buffer)
+                       break;
+
+               err = intel_pt_get_buffer(ptq, buffer, old_buffer, &b);
+               if (err)
+                       break;
+
+               if (b.len) {
+                       intel_pt_lookahead_drop_buffer(ptq, old_buffer);
+                       old_buffer = buffer;
+               } else {
+                       intel_pt_lookahead_drop_buffer(ptq, buffer);
+                       continue;
+               }
+
+               err = cb(&b, cb_data);
+               if (err)
+                       break;
+       }
+
+       if (buffer != old_buffer)
+               intel_pt_lookahead_drop_buffer(ptq, buffer);
+       intel_pt_lookahead_drop_buffer(ptq, old_buffer);
+
+       return err;
+}
+
+/*
+ * This function assumes data is processed sequentially only.
+ * Must be serialized with respect to intel_pt_lookahead()
+ */
 static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data)
 {
        struct intel_pt_queue *ptq = data;
@@ -827,6 +883,7 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
 
        params.get_trace = intel_pt_get_trace;
        params.walk_insn = intel_pt_walk_next_insn;
+       params.lookahead = intel_pt_lookahead;
        params.data = ptq;
        params.return_compression = intel_pt_return_compression(pt);
        params.branch_enable = intel_pt_branch_enable(pt);