[PATCH 08/19] perf tools: Flush ordered events in case of allocation failure

[Jiri Olsa <jolsa@kernel.org>]

In previous patches we added a limit for ordered events
queue allocation size. If we reach this size we need to
flush (part of) the queue to get some free buffers.

The current functionality is not affected, because the
limit is hard coded to (u64) -1. The configuration code
for size will come in following patches.

Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/builtin-kvm.c  |  2 +-
 tools/perf/util/session.c | 29 +++++++++++++++++++++++++++--
 tools/perf/util/session.h |  3 ++-
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index f8a561643753..f687228850d2 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 ebb87318c073..64c58e6f0923 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -15,6 +15,7 @@
 #include "cpumap.h"
 #include "perf_regs.h"
 #include "vdso.h"
+#include "asm/bug.h"
 
 static int perf_session__open(struct perf_session *session)
 {
@@ -458,6 +459,7 @@ 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)
@@ -639,6 +641,23 @@ 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;
@@ -701,7 +720,8 @@ 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;
@@ -716,6 +736,11 @@ 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 int 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);
 
-- 
1.8.3.1