3 files changed, 30 insertions, 4 deletions

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 258a5274099d..7ccceadcd9f8 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -732,7 +732,7 @@ static s64 perf_kvm__mmap_read_idx(struct perf_kvm_stat *kvm, int idx,
 			return -1;
 		}
 
-		err = perf_session_queue_event(kvm->session, event, &sample, 0);
+		err = perf_session_queue_event(kvm->session, event, &kvm->tool, &sample, 0);
 		/*
 		 * FIXME: Here we can't consume the event, as perf_session_queue_event will
 		 *        point to it, and it'll get possibly overwritten by the kernel.
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 8d4538c91076..bd2483b6b446 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -14,6 +14,7 @@
 #include "util.h"
 #include "cpumap.h"
 #include "perf_regs.h"
+#include "asm/bug.h"
 
 static int perf_session__open(struct perf_session *session)
 {
@@ -456,6 +457,7 @@ struct ordered_event {
 enum oe_flush {
 	OE_FLUSH__FINAL,
 	OE_FLUSH__ROUND,
+	OE_FLUSH__HALF,
 };
 
 static void perf_session_free_sample_buffers(struct perf_session *session)
@@ -637,6 +639,23 @@ static int ordered_events__flush(struct perf_session *s, struct perf_tool *tool,
 		oe->next_flush = ULLONG_MAX;
 		break;
 
+	case OE_FLUSH__HALF:
+	{
+		struct ordered_event *first, *last;
+		struct list_head *head = &oe->events;
+
+		first = list_entry(head->next, struct ordered_event, list);
+		last = oe->last;
+
+		/* Warn if we are called before any event got allocated. */
+		if (WARN_ONCE(!last || list_empty(head), "empty queue"))
+			return 0;
+
+		oe->next_flush  = first->timestamp;
+		oe->next_flush += (last->timestamp - first->timestamp) / 2;
+		break;
+	}
+
 	case OE_FLUSH__ROUND:
 	default:
 		break;
@@ -699,7 +718,8 @@ static int process_finished_round(struct perf_tool *tool,
 }
 
 int perf_session_queue_event(struct perf_session *s, union perf_event *event,
-				    struct perf_sample *sample, u64 file_offset)
+			     struct perf_tool *tool, struct perf_sample *sample,
+			     u64 file_offset)
 {
 	struct ordered_events *oe = &s->ordered_events;
 	u64 timestamp = sample->time;
@@ -714,6 +734,11 @@ int perf_session_queue_event(struct perf_session *s, union perf_event *event,
 	}
 
 	new = ordered_events__new(oe, timestamp);
+	if (!new) {
+		ordered_events__flush(s, tool, OE_FLUSH__HALF);
+		new = ordered_events__new(oe, timestamp);
+	}
+
 	if (!new)
 		return -ENOMEM;
 
@@ -1121,7 +1146,7 @@ static s64 perf_session__process_event(struct perf_session *session,
 		return ret;
 
 	if (tool->ordered_events) {
-		ret = perf_session_queue_event(session, event, &sample,
+		ret = perf_session_queue_event(session, event, tool, &sample,
 					       file_offset);
 		if (ret != -ETIME)
 			return ret;
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index e2fbaf2567e1..a09e3c8d825a 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -67,7 +67,8 @@ int perf_session__process_events(struct perf_session *session,
 				 struct perf_tool *tool);
 
 int perf_session_queue_event(struct perf_session *s, union perf_event *event,
-			     struct perf_sample *sample, u64 file_offset);
+			     struct perf_tool *tool, struct perf_sample *sample,
+			     u64 file_offset);
 
 void perf_tool__fill_defaults(struct perf_tool *tool);