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Commit 930e6fcd authored Jun 17, 2015 by Kan Liang Committed by Arnaldo Carvalho de Melo Jun 19, 2015

perf tools: Add time out to force stop proc map processing



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_PROC_MAP_PARSE_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: Ying Huang <ying.huang@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ying Huang <ying.huang@intel.com>
Link: http://lkml.kernel.org/r/1434549071-25611-1-git-send-email-kan.liang@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent c05676c0

include/uapi/linux/perf_event.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -565,6 +565,10 @@ struct perf_event_mmap_page {
		#define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0)
		#define PERF_RECORD_MISC_GUEST_USER (5 << 0)

		/*
		* Indicates that /proc/PID/maps parsing are truncated by time out.
		*/
		#define PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT (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.

tools/perf/util/event.c

+18 −0

Original line number	Diff line number	Diff line
		@@ -213,6 +213,8 @@ static int perf_event__synthesize_fork(struct perf_tool *tool,
		return 0;
		}

		#define PROC_MAP_PARSE_TIMEOUT (500 * 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 truncation = 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) > PROC_MAP_PARSE_TIMEOUT) {
		pr_warning("Reading %s time out.\n", filename);
		truncation = 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 (truncation)
		event->header.misc \|= PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT;

		if (!strcmp(execname, ""))
		strcpy(execname, anonstr);

		@@ -319,6 +334,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
		rc = -1;
		break;
		}

		if (truncation)
		break;
		}

		fclose(fp);

tools/perf/util/event.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 {

tools/perf/util/session.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -1064,6 +1064,8 @@ 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_PROC_MAP_PARSE_TIMEOUT)
		++evlist->stats.nr_proc_map_timeout;
		return tool->mmap2(tool, event, sample, machine);
		case PERF_RECORD_COMM:
		return tool->comm(tool, event, sample, machine);
		@@ -1360,6 +1362,15 @@ 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);
		}
		}

		static int perf_session__flush_thread_stack(struct thread *thread,