[PATCH 11/11] perf kvm top: limit guest kernel info message to once

[David Ahern]

'perf kvm top' shows a continual flurry of:
    Can't find guest [5201]'s kernel information

if it can't find the guest info and with a lot of VMs running a user
has no chance of reading them all. Limit message to once per guest.

Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 tools/perf/builtin-top.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 1706dc9..6285374 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -706,8 +706,18 @@ static void perf_event__process_sample(struct perf_tool *tool,
 	int err;
 
 	if (!machine && perf_guest) {
-		pr_err("Can't find guest [%d]'s kernel information\n",
-			event->ip.pid);
+		static struct strlist *seen;
+		char pidstr[8];
+
+		if (!seen)
+			seen = strlist__new(true, NULL);
+
+		scnprintf(pidstr, sizeof(pidstr), "%d", event->ip.pid);
+		if (!strlist__has_entry(seen, pidstr)) {
+			pr_err("Can't find guest [%d]'s kernel information\n",
+				event->ip.pid);
+			strlist__add(seen, pidstr);
+		}
 		return;
 	}
 
-- 
1.7.10.1

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