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Message-Id: <1434527812-17051-1-git-send-email-kan.liang@intel.com>
Date: Wed, 17 Jun 2015 03:56:51 -0400
From: kan.liang@...el.com
To: acme@...nel.org
Cc: linux-kernel@...r.kernel.org, dsahern@...il.com,
ying.huang@...el.com, andi@...stfloor.org,
Kan Liang <kan.liang@...el.com>
Subject: [PATCH V3 1/2] perf,tools: add time out to force stop proc map processing
From: Kan Liang <kan.liang@...el.com>
System wide sampling like 'perf top' or 'perf record -a' read all
threads /proc/xxx/maps before sampling. If there are any threads which
generating a keeping growing huge maps, perf will do infinite loop
during synthesizing. Nothing will be sampled.
This patch fixes this issue by adding per-thread timeout to force stop
this kind of endless proc map processing.
PERF_RECORD_MISC_MMAP_TIME_OUT is introduced to indicate that the mmap
record are truncated by time out. User will get warning notification
when truncated mmap records are detected.
Reported-by: Huang, Ying <ying.huang@...el.com>
Signed-off-by: Kan Liang <kan.liang@...el.com>
---
Changes since V1
- Add warning message for time out.
Changes since V2
- Handle time out warning in perf_session__warn_about_errors
- Configurable time out (patch 2/2)
include/uapi/linux/perf_event.h | 4 ++++
tools/perf/util/event.c | 18 ++++++++++++++++++
tools/perf/util/event.h | 1 +
tools/perf/util/session.c | 11 +++++++++++
4 files changed, 34 insertions(+)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 613ed9a..b3904ba 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -566,6 +566,10 @@ struct perf_event_mmap_page {
#define PERF_RECORD_MISC_GUEST_USER (5 << 0)
/*
+ * Indicates that /proc/PID/maps parsing are truncated by time out.
+ */
+#define PERF_RECORD_MISC_MMAP_TIME_OUT (1 << 12)
+/*
* PERF_RECORD_MISC_MMAP_DATA and PERF_RECORD_MISC_COMM_EXEC are used on
* different events so can reuse the same bit position.
*/
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 793b150..ac6cf2a 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -213,6 +213,8 @@ static int perf_event__synthesize_fork(struct perf_tool *tool,
return 0;
}
+#define MMAP_TIMEOUT (50 * 1000000ULL)
+
int perf_event__synthesize_mmap_events(struct perf_tool *tool,
union perf_event *event,
pid_t pid, pid_t tgid,
@@ -222,6 +224,8 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
{
char filename[PATH_MAX];
FILE *fp;
+ unsigned long long t;
+ bool timeout = false;
int rc = 0;
if (machine__is_default_guest(machine))
@@ -240,6 +244,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
}
event->header.type = PERF_RECORD_MMAP2;
+ t = rdclock();
while (1) {
char bf[BUFSIZ];
@@ -253,6 +258,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
if (fgets(bf, sizeof(bf), fp) == NULL)
break;
+ if ((rdclock() - t) > MMAP_TIMEOUT) {
+ pr_warning("Reading %s time out.\n", filename);
+ timeout = true;
+ goto out;
+ }
+
/* ensure null termination since stack will be reused. */
strcpy(execname, "");
@@ -301,6 +312,10 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
event->header.misc |= PERF_RECORD_MISC_MMAP_DATA;
}
+out:
+ if (timeout)
+ event->header.misc |= PERF_RECORD_MISC_MMAP_TIME_OUT;
+
if (!strcmp(execname, ""))
strcpy(execname, anonstr);
@@ -319,6 +334,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
rc = -1;
break;
}
+
+ if (timeout)
+ break;
}
fclose(fp);
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 5dc51ad..39868f5 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -265,6 +265,7 @@ struct events_stats {
u32 nr_unknown_id;
u32 nr_unprocessable_samples;
u32 nr_auxtrace_errors[PERF_AUXTRACE_ERROR_MAX];
+ u32 nr_proc_map_timeout;
};
struct attr_event {
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 88d87bf..8561d8b 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1041,6 +1041,8 @@ static int machines__deliver_event(struct machines *machines,
case PERF_RECORD_MMAP:
return tool->mmap(tool, event, sample, machine);
case PERF_RECORD_MMAP2:
+ if (event->header.misc & PERF_RECORD_MISC_MMAP_TIME_OUT)
+ ++evlist->stats.nr_proc_map_timeout;
return tool->mmap2(tool, event, sample, machine);
case PERF_RECORD_COMM:
return tool->comm(tool, event, sample, machine);
@@ -1337,6 +1339,15 @@ static void perf_session__warn_about_errors(const struct perf_session *session)
ui__warning("%u out of order events recorded.\n", oe->nr_unordered_events);
events_stats__auxtrace_error_warn(stats);
+
+ if (stats->nr_proc_map_timeout != 0) {
+ ui__warning("%d map information files for pre-existing threads were\n"
+ "not processed, if there are samples for addresses they\n"
+ "will not be resolved, you may find out which are these\n"
+ "threads by running with -v and redirecting the output\n"
+ "to a file.\n",
+ stats->nr_proc_map_timeout);
+ }
}
volatile int session_done;
--
1.8.3.1
--
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