diff --git a/tools/perf/Documentation/perf-kvm.txt b/tools/perf/Documentation/perf-kvm.txt
index 6252e77..6a5bb2b 100644
--- a/tools/perf/Documentation/perf-kvm.txt
+++ b/tools/perf/Documentation/perf-kvm.txt
@@ -151,6 +151,12 @@
        Show events other than HLT (x86 only) or Wait state (s390 only)
        that take longer than duration usecs.
 
+--proc-map-timeout::
+	When processing pre-existing threads /proc/XXX/mmap, it may take
+	a long time, because the file may be huge. A time out is needed
+	in such cases.
+	This option sets the time out limit. The default value is 500 ms.
+
 SEE ALSO
 --------
 linkperf:perf-top[1], linkperf:perf-record[1], linkperf:perf-report[1],
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 6fdf786..9b9d9d0 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -271,6 +271,11 @@
 snapshot can be specified. In Snapshot Mode, trace data is captured only when
 signal SIGUSR2 is received.
 
+--proc-map-timeout::
+When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
+because the file may be huge. A time out is needed in such cases.
+This option sets the time out limit. The default value is 500 ms.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index 9e5b07eb..776aec4 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -201,6 +201,12 @@
 	Force each column width to the provided list, for large terminal
 	readability.  0 means no limit (default behavior).
 
+--proc-map-timeout::
+	When processing pre-existing threads /proc/XXX/mmap, it may take
+	a long time, because the file may be huge. A time out is needed
+	in such cases.
+	This option sets the time out limit. The default value is 500 ms.
+
 
 INTERACTIVE PROMPTING KEYS
 --------------------------
diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index 1db9c8b..7ea0786 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -121,6 +121,11 @@
 --event::
 	Trace other events, see 'perf list' for a complete list.
 
+--proc-map-timeout::
+	When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
+	because the file may be huge. A time out is needed in such cases.
+	This option sets the time out limit. The default value is 500 ms.
+
 PAGEFAULTS
 ----------
 
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 15fecd3..74878cd 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1311,6 +1311,8 @@
 			"show events other than"
 			" HLT (x86 only) or Wait state (s390 only)"
 			" that take longer than duration usecs"),
+		OPT_UINTEGER(0, "proc-map-timeout", &kvm->opts.proc_map_timeout,
+				"per thread proc mmap processing timeout in ms"),
 		OPT_END()
 	};
 	const char * const live_usage[] = {
@@ -1338,6 +1340,7 @@
 	kvm->opts.target.uses_mmap = false;
 	kvm->opts.target.uid_str = NULL;
 	kvm->opts.target.uid = UINT_MAX;
+	kvm->opts.proc_map_timeout = 500;
 
 	symbol__init(NULL);
 	disable_buildid_cache();
@@ -1393,7 +1396,7 @@
 	perf_session__set_id_hdr_size(kvm->session);
 	ordered_events__set_copy_on_queue(&kvm->session->ordered_events, true);
 	machine__synthesize_threads(&kvm->session->machines.host, &kvm->opts.target,
-				    kvm->evlist->threads, false);
+				    kvm->evlist->threads, false, kvm->opts.proc_map_timeout);
 	err = kvm_live_open_events(kvm);
 	if (err)
 		goto out;
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4d6cdeb..de165a1 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -598,7 +598,8 @@
 	}
 
 	err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
-					    process_synthesized_event, opts->sample_address);
+					    process_synthesized_event, opts->sample_address,
+					    opts->proc_map_timeout);
 	if (err != 0)
 		goto out_child;
 
@@ -959,6 +960,7 @@
 			.uses_mmap   = true,
 			.default_per_cpu = true,
 		},
+		.proc_map_timeout     = 500,
 	},
 	.tool = {
 		.sample		= process_sample_event,
@@ -1066,6 +1068,8 @@
 	parse_clockid),
 	OPT_STRING_OPTARG('S', "snapshot", &record.opts.auxtrace_snapshot_opts,
 			  "opts", "AUX area tracing Snapshot Mode", ""),
+	OPT_UINTEGER(0, "proc-map-timeout", &record.opts.proc_map_timeout,
+			"per thread proc mmap processing timeout in ms"),
 	OPT_END()
 };
 
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 70a9505..619a869 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -977,7 +977,7 @@
 		goto out_delete;
 
 	machine__synthesize_threads(&top->session->machines.host, &opts->target,
-				    top->evlist->threads, false);
+				    top->evlist->threads, false, opts->proc_map_timeout);
 	ret = perf_top__start_counters(top);
 	if (ret)
 		goto out_delete;
@@ -1087,6 +1087,7 @@
 			.target		= {
 				.uses_mmap   = true,
 			},
+			.proc_map_timeout    = 500,
 		},
 		.max_stack	     = PERF_MAX_STACK_DEPTH,
 		.sym_pcnt_filter     = 5,
@@ -1186,6 +1187,8 @@
 	OPT_STRING('w', "column-widths", &symbol_conf.col_width_list_str,
 		   "width[,width...]",
 		   "don't try to adjust column width, use these fixed values"),
+	OPT_UINTEGER(0, "proc-map-timeout", &opts->proc_map_timeout,
+			"per thread proc mmap processing timeout in ms"),
 	OPT_END()
 	};
 	const char * const top_usage[] = {
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 4bf805b..de5d277 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1518,7 +1518,8 @@
 		return -ENOMEM;
 
 	err = __machine__synthesize_threads(trace->host, &trace->tool, &trace->opts.target,
-					    evlist->threads, trace__tool_process, false);
+					    evlist->threads, trace__tool_process, false,
+					    trace->opts.proc_map_timeout);
 	if (err)
 		symbol__exit();
 
@@ -2747,6 +2748,7 @@
 			.user_interval = ULLONG_MAX,
 			.no_buffering  = true,
 			.mmap_pages    = UINT_MAX,
+			.proc_map_timeout  = 500,
 		},
 		.output = stdout,
 		.show_comm = true,
@@ -2796,6 +2798,8 @@
 		     "Trace pagefaults", parse_pagefaults, "maj"),
 	OPT_BOOLEAN(0, "syscalls", &trace.trace_syscalls, "Trace syscalls"),
 	OPT_BOOLEAN('f', "force", &trace.force, "don't complain, do it"),
+	OPT_UINTEGER(0, "proc-map-timeout", &trace.opts.proc_map_timeout,
+			"per thread proc mmap processing timeout in ms"),
 	OPT_END()
 	};
 	const char * const trace_subcommands[] = { "record", NULL };
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index aa79fb8..4a5827ff 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -69,6 +69,7 @@
 	unsigned     initial_delay;
 	bool         use_clockid;
 	clockid_t    clockid;
+	unsigned int proc_map_timeout;
 };
 
 struct option;
diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index e2a432b..22f8a00 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -451,7 +451,7 @@
 	}
 
 	ret = perf_event__synthesize_thread_map(NULL, threads,
-						perf_event__process, machine, false);
+						perf_event__process, machine, false, 500);
 	if (ret < 0) {
 		pr_debug("perf_event__synthesize_thread_map failed\n");
 		goto out_err;
diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index 9b748e1..40b36c4 100644
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -28,7 +28,7 @@
 	pid_t pid = getpid();
 
 	return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
-						  mmap_handler, machine, true);
+						  mmap_handler, machine, true, 500);
 }
 
 #define MAX_STACK 8
diff --git a/tools/perf/tests/mmap-thread-lookup.c b/tools/perf/tests/mmap-thread-lookup.c
index 264e215..7f48efa 100644
--- a/tools/perf/tests/mmap-thread-lookup.c
+++ b/tools/perf/tests/mmap-thread-lookup.c
@@ -129,7 +129,7 @@
 {
 	return perf_event__synthesize_threads(NULL,
 					      perf_event__process,
-					      machine, 0);
+					      machine, 0, 500);
 }
 
 static int synth_process(struct machine *machine)
@@ -141,7 +141,7 @@
 
 	err = perf_event__synthesize_thread_map(NULL, map,
 						perf_event__process,
-						machine, 0);
+						machine, 0, 500);
 
 	thread_map__delete(map);
 	return err;
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 416ba80..d7d986d 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -213,19 +213,19 @@
 	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,
 				       perf_event__handler_t process,
 				       struct machine *machine,
-				       bool mmap_data)
+				       bool mmap_data,
+				       unsigned int proc_map_timeout)
 {
 	char filename[PATH_MAX];
 	FILE *fp;
 	unsigned long long t;
 	bool truncation = false;
+	unsigned long long timeout = proc_map_timeout * 1000000ULL;
 	int rc = 0;
 
 	if (machine__is_default_guest(machine))
@@ -258,8 +258,11 @@
 		if (fgets(bf, sizeof(bf), fp) == NULL)
 			break;
 
-		if ((rdclock() - t) > PROC_MAP_PARSE_TIMEOUT) {
-			pr_warning("Reading %s time out.\n", filename);
+		if ((rdclock() - t) > timeout) {
+			pr_warning("Reading %s time out. "
+				   "You may want to increase "
+				   "the time limit by --proc-map-timeout\n",
+				   filename);
 			truncation = true;
 			goto out;
 		}
@@ -404,7 +407,9 @@
 				      pid_t pid, int full,
 					  perf_event__handler_t process,
 				      struct perf_tool *tool,
-				      struct machine *machine, bool mmap_data)
+				      struct machine *machine,
+				      bool mmap_data,
+				      unsigned int proc_map_timeout)
 {
 	char filename[PATH_MAX];
 	DIR *tasks;
@@ -421,7 +426,8 @@
 			return -1;
 
 		return perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
-							  process, machine, mmap_data);
+							  process, machine, mmap_data,
+							  proc_map_timeout);
 	}
 
 	if (machine__is_default_guest(machine))
@@ -462,7 +468,7 @@
 		if (_pid == pid) {
 			/* process the parent's maps too */
 			rc = perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
-						process, machine, mmap_data);
+						process, machine, mmap_data, proc_map_timeout);
 			if (rc)
 				break;
 		}
@@ -476,7 +482,8 @@
 				      struct thread_map *threads,
 				      perf_event__handler_t process,
 				      struct machine *machine,
-				      bool mmap_data)
+				      bool mmap_data,
+				      unsigned int proc_map_timeout)
 {
 	union perf_event *comm_event, *mmap_event, *fork_event;
 	int err = -1, thread, j;
@@ -499,7 +506,7 @@
 					       fork_event,
 					       threads->map[thread], 0,
 					       process, tool, machine,
-					       mmap_data)) {
+					       mmap_data, proc_map_timeout)) {
 			err = -1;
 			break;
 		}
@@ -525,7 +532,7 @@
 						       fork_event,
 						       comm_event->comm.pid, 0,
 						       process, tool, machine,
-						       mmap_data)) {
+						       mmap_data, proc_map_timeout)) {
 				err = -1;
 				break;
 			}
@@ -542,7 +549,9 @@
 
 int perf_event__synthesize_threads(struct perf_tool *tool,
 				   perf_event__handler_t process,
-				   struct machine *machine, bool mmap_data)
+				   struct machine *machine,
+				   bool mmap_data,
+				   unsigned int proc_map_timeout)
 {
 	DIR *proc;
 	char proc_path[PATH_MAX];
@@ -582,7 +591,8 @@
  		 * one thread couldn't be synthesized.
  		 */
 		__event__synthesize_thread(comm_event, mmap_event, fork_event, pid,
-					   1, process, tool, machine, mmap_data);
+					   1, process, tool, machine, mmap_data,
+					   proc_map_timeout);
 	}
 
 	err = 0;
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 39868f5..c53f363 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -384,10 +384,12 @@
 int perf_event__synthesize_thread_map(struct perf_tool *tool,
 				      struct thread_map *threads,
 				      perf_event__handler_t process,
-				      struct machine *machine, bool mmap_data);
+				      struct machine *machine, bool mmap_data,
+				      unsigned int proc_map_timeout);
 int perf_event__synthesize_threads(struct perf_tool *tool,
 				   perf_event__handler_t process,
-				   struct machine *machine, bool mmap_data);
+				   struct machine *machine, bool mmap_data,
+				   unsigned int proc_map_timeout);
 int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 				       perf_event__handler_t process,
 				       struct machine *machine);
@@ -469,7 +471,8 @@
 				       pid_t pid, pid_t tgid,
 				       perf_event__handler_t process,
 				       struct machine *machine,
-				       bool mmap_data);
+				       bool mmap_data,
+				       unsigned int proc_map_timeout);
 
 size_t perf_event__fprintf_comm(union perf_event *event, FILE *fp);
 size_t perf_event__fprintf_mmap(union perf_event *event, FILE *fp);
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 8b3b193..4744673 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1913,12 +1913,13 @@
 
 int __machine__synthesize_threads(struct machine *machine, struct perf_tool *tool,
 				  struct target *target, struct thread_map *threads,
-				  perf_event__handler_t process, bool data_mmap)
+				  perf_event__handler_t process, bool data_mmap,
+				  unsigned int proc_map_timeout)
 {
 	if (target__has_task(target))
-		return perf_event__synthesize_thread_map(tool, threads, process, machine, data_mmap);
+		return perf_event__synthesize_thread_map(tool, threads, process, machine, data_mmap, proc_map_timeout);
 	else if (target__has_cpu(target))
-		return perf_event__synthesize_threads(tool, process, machine, data_mmap);
+		return perf_event__synthesize_threads(tool, process, machine, data_mmap, proc_map_timeout);
 	/* command specified */
 	return 0;
 }
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index cea62f6..887798e 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -222,13 +222,16 @@
 
 int __machine__synthesize_threads(struct machine *machine, struct perf_tool *tool,
 				  struct target *target, struct thread_map *threads,
-				  perf_event__handler_t process, bool data_mmap);
+				  perf_event__handler_t process, bool data_mmap,
+				  unsigned int proc_map_timeout);
 static inline
 int machine__synthesize_threads(struct machine *machine, struct target *target,
-				struct thread_map *threads, bool data_mmap)
+				struct thread_map *threads, bool data_mmap,
+				unsigned int proc_map_timeout)
 {
 	return __machine__synthesize_threads(machine, NULL, target, threads,
-					     perf_event__process, data_mmap);
+					     perf_event__process, data_mmap,
+					     proc_map_timeout);
 }
 
 pid_t machine__get_current_tid(struct machine *machine, int cpu);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 2d882fd..aa482c1 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1368,7 +1368,9 @@
 			    "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",
+			    "to a file.\n"
+			    "The time limit to process proc map is too short?\n"
+			    "Increase it by --proc-map-timeout\n",
 			    stats->nr_proc_map_timeout);
 	}
 }