perf kvm: Option to print events that exceed a duration

This is useful to spot high latency blips. It is normal for HLT reasons
to have long exit times, so strip those from the duration check.

v2: changed threshold to duration per acme's request

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Runzhen Wang <runzhen@linux.vnet.ibm.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1375926999-75129-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 21 insertions, 4 deletions

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 2ceec817a2fb..fa2f3d79886a 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -106,6 +106,7 @@ struct perf_kvm_stat {
         u64 total_time;
         u64 total_count;
         u64 lost_events;
+        u64 duration;
 
         const char *pid_str;
         struct intlist *pid_list;
@@ -473,7 +474,7 @@ static bool update_kvm_event(struct kvm_event *event, int vcpu_id,
 static bool handle_end_event(struct perf_kvm_stat *kvm,
                              struct vcpu_event_record *vcpu_record,
                              struct event_key *key,
-                             u64 timestamp)
+                             struct perf_sample *sample)
 {
         struct kvm_event *event;
         u64 time_begin, time_diff;
@@ -510,12 +511,24 @@ static bool handle_end_event(struct perf_kvm_stat *kvm,
         vcpu_record->start_time = 0;
 
         /* seems to happen once in a while during live mode */
-        if (timestamp < time_begin) {
+        if (sample->time < time_begin) {
                 pr_debug("End time before begin time; skipping event.\n");
                 return true;
         }
 
-        time_diff = timestamp - time_begin;
+        time_diff = sample->time - time_begin;
+
+        if (kvm->duration && time_diff > kvm->duration) {
+                char decode[32];
+
+                kvm->events_ops->decode_key(kvm, &event->key, decode);
+                if (strcmp(decode, "HLT")) {
+                        pr_info("%" PRIu64 " VM %d, vcpu %d: %s event took %" PRIu64 "usec\n",
+                                 sample->time, sample->pid, vcpu_record->vcpu_id,
+                                 decode, time_diff/1000);
+                }
+        }
+
         return update_kvm_event(event, vcpu, time_diff);
 }
 
@@ -562,7 +575,7 @@ static bool handle_kvm_event(struct perf_kvm_stat *kvm,
                 return handle_begin_event(kvm, vcpu_record, &key, sample->time);
 
         if (kvm->events_ops->is_end_event(evsel, sample, &key))
-                return handle_end_event(kvm, vcpu_record, &key, sample->time);
+                return handle_end_event(kvm, vcpu_record, &key, sample);
 
         return true;
 }
@@ -1429,6 +1442,8 @@ static int kvm_events_live(struct perf_kvm_stat *kvm,
                 OPT_STRING('k', "key", &kvm->sort_key, "sort-key",
                         "key for sorting: sample(sort by samples number)"
                         " time (sort by avg time)"),
+                OPT_U64(0, "duration", &kvm->duration,
+                    "show events other than HALT that take longer than duration usecs"),
                 OPT_END()
         };
         const char * const live_usage[] = {
@@ -1467,6 +1482,8 @@ static int kvm_events_live(struct perf_kvm_stat *kvm,
                         usage_with_options(live_usage, live_options);
         }
 
+        kvm->duration *= NSEC_PER_USEC;   /* convert usec to nsec */
+
         /*
          * target related setups
          */