perf/core improvements and fixes

index f954c26de231..5ab2f674fed2 100644
@@ -1276,11 +1276,11 @@ static const char *thread__fd_path(struct thread *thread, int fd,
 	if (fd < 0)
 		return NULL;
 
-	if ((fd > ttrace->paths.max || ttrace->paths.table[fd] == NULL))
+	if ((fd > ttrace->paths.max || ttrace->paths.table[fd] == NULL)) {
 		if (!trace->live)
 			return NULL;
 		++trace->stats.proc_getname;
-		if (thread__read_fd_path(thread, fd)) {
+		if (thread__read_fd_path(thread, fd))
 			return NULL;
 	}
 

index 59ef2802fcf6..c51223ac25f4 100644
@@ -1214,10 +1214,11 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused,
 					     "For your workloads it needs to be <= 1\nHint:\t");
 		}
 		printed += scnprintf(buf + printed, size - printed,
-				     "For system wide tracing it needs to be set to -1");
+				     "For system wide tracing it needs to be set to -1.\n");
 
 		printed += scnprintf(buf + printed, size - printed,
-				    ".\nHint:\tThe current value is %d.", value);
+				    "Hint:\tTry: 'sudo sh -c \"echo -1 > /proc/sys/kernel/perf_event_paranoid\"'\n"
+				    "Hint:\tThe current value is %d.", value);
 		break;
 	default:
 		scnprintf(buf, size, "%s", emsg);

index 5ab2f674fed2..28c86e21fad9 100644
@@ -1629,7 +1629,6 @@ static int trace__sys_enter(struct trace *trace, struct perf_evsel *evsel,
 		return -1;
 
 	args = perf_evsel__sc_tp_ptr(evsel, args, sample);
-	ttrace = thread->priv;
 
 	if (ttrace->entry_str == NULL) {
 		ttrace->entry_str = malloc(1024);

@@ -1687,8 +1686,6 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel,
 		++trace->stats.vfs_getname;
 	}
 
-	ttrace = thread->priv;
-
 	ttrace->exit_time = sample->time;
 
 	if (ttrace->entry_time) {

index 28c86e21fad9..5549cee61680 100644
@@ -1108,6 +1108,7 @@ struct syscall {
 	struct event_format *tp_format;
 	const char	    *name;
 	bool		    filtered;
+	bool		    is_exit;
 	struct syscall_fmt  *fmt;
 	size_t		    (**arg_scnprintf)(char *bf, size_t size, struct syscall_arg *arg);
 	void		    **arg_parm;

@@ -1473,6 +1474,8 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 	if (sc->tp_format == NULL)
 		return -1;
 
+	sc->is_exit = !strcmp(name, "exit_group") || !strcmp(name, "exit");
+
 	return syscall__set_arg_fmts(sc);
 }
 

@@ -1643,7 +1646,7 @@ static int trace__sys_enter(struct trace *trace, struct perf_evsel *evsel,
 	printed += syscall__scnprintf_args(sc, msg + printed, 1024 - printed,
 					   args, trace, thread);
 
-	if (!strcmp(sc->name, "exit_group") || !strcmp(sc->name, "exit")) {
+	if (sc->is_exit) {
 		if (!trace->duration_filter && !trace->summary_only) {
 			trace__fprintf_entry_head(trace, thread, 1, sample->time, trace->output);
 			fprintf(trace->output, "%-70s\n", ttrace->entry_str);

index 52c03fbbba17..1bd35e8ed9f1 100644
@@ -32,8 +32,7 @@ struct hist_browser {
 
 extern void hist_browser__init_hpp(void);
 
-static int hists__browser_title(struct hists *hists, char *bf, size_t size,
-				const char *ev_name);
+static int hists__browser_title(struct hists *hists, char *bf, size_t size);
 static void hist_browser__update_nr_entries(struct hist_browser *hb);
 
 static struct rb_node *hists__filter_entries(struct rb_node *nd,

@@ -345,7 +344,7 @@ static void ui_browser__warn_lost_events(struct ui_browser *browser)
 		"Or reduce the sampling frequency.");
 }
 
-static int hist_browser__run(struct hist_browser *browser, const char *ev_name,
+static int hist_browser__run(struct hist_browser *browser,
 			     struct hist_browser_timer *hbt)
 {
 	int key;

@@ -356,7 +355,7 @@ static int hist_browser__run(struct hist_browser *browser, const char *ev_name,
 	browser->b.nr_entries = hist_browser__nr_entries(browser);
 
 	hist_browser__refresh_dimensions(browser);
-	hists__browser_title(browser->hists, title, sizeof(title), ev_name);
+	hists__browser_title(browser->hists, title, sizeof(title));
 
 	if (ui_browser__show(&browser->b, title,
 			     "Press '?' for help on key bindings") < 0)

@@ -383,7 +382,7 @@ static int hist_browser__run(struct hist_browser *browser, const char *ev_name,
 				ui_browser__warn_lost_events(&browser->b);
 			}
 
-			hists__browser_title(browser->hists, title, sizeof(title), ev_name);
+			hists__browser_title(browser->hists, title, sizeof(title));
 			ui_browser__show_title(&browser->b, title);
 			continue;
 		}

@@ -1212,8 +1211,7 @@ static struct thread *hist_browser__selected_thread(struct hist_browser *browser
 	return browser->he_selection->thread;
 }
 
-static int hists__browser_title(struct hists *hists, char *bf, size_t size,
-				const char *ev_name)
+static int hists__browser_title(struct hists *hists, char *bf, size_t size)
 {
 	char unit;
 	int printed;

@@ -1222,6 +1220,7 @@ static int hists__browser_title(struct hists *hists, char *bf, size_t size,
 	unsigned long nr_samples = hists->stats.nr_events[PERF_RECORD_SAMPLE];
 	u64 nr_events = hists->stats.total_period;
 	struct perf_evsel *evsel = hists_to_evsel(hists);
+	const char *ev_name = perf_evsel__name(evsel);
 	char buf[512];
 	size_t buflen = sizeof(buf);
 

@@ -1389,7 +1388,7 @@ static void hist_browser__update_nr_entries(struct hist_browser *hb)
 }
 
 static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
-				    const char *helpline, const char *ev_name,
+				    const char *helpline,
 				    bool left_exits,
 				    struct hist_browser_timer *hbt,
 				    float min_pcnt,

@@ -1464,7 +1463,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 
 		nr_options = 0;
 
-		key = hist_browser__run(browser, ev_name, hbt);
+		key = hist_browser__run(browser, hbt);
 
 		if (browser->he_selection != NULL) {
 			thread = hist_browser__selected_thread(browser);

@@ -1832,7 +1831,7 @@ static int perf_evsel_menu__run(struct perf_evsel_menu *menu,
 {
 	struct perf_evlist *evlist = menu->b.priv;
 	struct perf_evsel *pos;
-	const char *ev_name, *title = "Available samples";
+	const char *title = "Available samples";
 	int delay_secs = hbt ? hbt->refresh : 0;
 	int key;
 

@@ -1865,9 +1864,8 @@ browse_hists:
 			 */
 			if (hbt)
 				hbt->timer(hbt->arg);
-			ev_name = perf_evsel__name(pos);
 			key = perf_evsel__hists_browse(pos, nr_events, help,
-						       ev_name, true, hbt,
+						       true, hbt,
 						       menu->min_pcnt,
 						       menu->env);
 			ui_browser__show_title(&menu->b, title);

@@ -1971,10 +1969,9 @@ int perf_evlist__tui_browse_hists(struct perf_evlist *evlist, const char *help,
 single_entry:
 	if (nr_entries == 1) {
 		struct perf_evsel *first = perf_evlist__first(evlist);
-		const char *ev_name = perf_evsel__name(first);
 
 		return perf_evsel__hists_browse(first, nr_entries, help,
-						ev_name, false, hbt, min_pcnt,
+						false, hbt, min_pcnt,
 						env);
 	}
 

index 3ccf6e14f89b..9d2294efc00c 100644
@@ -279,7 +279,7 @@ static void ui_browser__scrollbar_set(struct ui_browser *browser)
 {
 	int height = browser->height, h = 0, pct = 0,
 	    col = browser->width,
-	    row = browser->y - 1;
+	    row = 0;
 
 	if (browser->nr_entries > 1) {
 		pct = ((browser->index * (browser->height - 1)) /

index cc1190a0849b..fc4fe91ee098 100644
@@ -332,5 +332,7 @@ int bench_sched_messaging(int argc, const char **argv,
 		break;
 	}
 
+	free(pth_tab);
+
 	return 0;
 }

index eba46709b279..3c4dd44d45cb 100644
@@ -43,5 +43,6 @@ extern int bench_futex_requeue(int argc, const char **argv, const char *prefix);
 #define BENCH_FORMAT_UNKNOWN		-1
 
 extern int bench_format;
+extern unsigned int bench_repeat;
 
 #endif

index 1e6e77710545..b9a56fa83330 100644
@@ -104,9 +104,11 @@ static const char *bench_format_str;
 
 /* Output/formatting style, exported to benchmark modules: */
 int bench_format = BENCH_FORMAT_DEFAULT;
+unsigned int bench_repeat = 10; /* default number of times to repeat the run */
 
 static const struct option bench_options[] = {
 	OPT_STRING('f', "format", &bench_format_str, "default", "Specify format style"),
+	OPT_UINTEGER('r', "repeat",  &bench_repeat,   "Specify amount of times to repeat the run"),
 	OPT_END()
 };
 

@@ -226,6 +228,11 @@ int cmd_bench(int argc, const char **argv, const char *prefix __maybe_unused)
 		goto end;
 	}
 
+	if (bench_repeat == 0) {
+		printf("Invalid repeat option: Must specify a positive value\n");
+		goto end;
+	}
+
 	if (argc < 1) {
 		print_usage();
 		goto end;

index a16255876f1d..732403bfd31a 100644
@@ -29,13 +29,6 @@ static u_int32_t futex1 = 0, futex2 = 0;
  */
 static unsigned int nrequeue = 1;
 
-/*
- * There can be significant variance from run to run,
- * the more repeats, the more exact the overall avg and
- * the better idea of the futex latency.
- */
-static unsigned int repeat = 10;
-
 static pthread_t *worker;
 static bool done = 0, silent = 0;
 static pthread_mutex_t thread_lock;

@@ -46,7 +39,6 @@ static unsigned int ncpus, threads_starting, nthreads = 0;
 static const struct option options[] = {
 	OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('q', "nrequeue", &nrequeue, "Specify amount of threads to requeue at once"),
-	OPT_UINTEGER('r', "repeat",   &repeat,   "Specify amount of times to repeat the run"),
 	OPT_BOOLEAN( 's', "silent",   &silent,   "Silent mode: do not display data/details"),
 	OPT_END()
 };

@@ -146,7 +138,7 @@ int bench_futex_requeue(int argc, const char **argv,
 	pthread_cond_init(&thread_parent, NULL);
 	pthread_cond_init(&thread_worker, NULL);
 
-	for (j = 0; j < repeat && !done; j++) {
+	for (j = 0; j < bench_repeat && !done; j++) {
 		unsigned int nrequeued = 0;
 		struct timeval start, end, runtime;
 

index d096169b161e..50022cbce87e 100644
@@ -30,15 +30,8 @@ static u_int32_t futex1 = 0;
  */
 static unsigned int nwakes = 1;
 
-/*
- * There can be significant variance from run to run,
- * the more repeats, the more exact the overall avg and
- * the better idea of the futex latency.
- */
-static unsigned int repeat = 10;
-
 pthread_t *worker;
-static bool done = 0, silent = 0;
+static bool done = false, silent = false;
 static pthread_mutex_t thread_lock;
 static pthread_cond_t thread_parent, thread_worker;
 static struct stats waketime_stats, wakeup_stats;

@@ -47,7 +40,6 @@ static unsigned int ncpus, threads_starting, nthreads = 0;
 static const struct option options[] = {
 	OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('w', "nwakes",  &nwakes,   "Specify amount of threads to wake at once"),
-	OPT_UINTEGER('r', "repeat",  &repeat,   "Specify amount of times to repeat the run"),
 	OPT_BOOLEAN( 's', "silent",  &silent,   "Silent mode: do not display data/details"),
 	OPT_END()
 };

@@ -149,7 +141,7 @@ int bench_futex_wake(int argc, const char **argv,
 	pthread_cond_init(&thread_parent, NULL);
 	pthread_cond_init(&thread_worker, NULL);
 
-	for (j = 0; j < repeat && !done; j++) {
+	for (j = 0; j < bench_repeat && !done; j++) {
 		unsigned int nwoken = 0;
 		struct timeval start, end, runtime;
 

index 5ce71d3b72cf..e622c3e96efc 100644
@@ -189,6 +189,11 @@ int bench_mem_memcpy(int argc, const char **argv,
 	argc = parse_options(argc, argv, options,
 			     bench_mem_memcpy_usage, 0);
 
+	if (no_prefault && only_prefault) {
+		fprintf(stderr, "Invalid options: -o and -n are mutually exclusive\n");
+		return 1;
+	}
+
 	if (use_cycle)
 		init_cycle();
 

index 9af79d2b18e5..2a65468619f0 100644
@@ -181,6 +181,11 @@ int bench_mem_memset(int argc, const char **argv,
 	argc = parse_options(argc, argv, options,
 			     bench_mem_memset_usage, 0);
 
+	if (no_prefault && only_prefault) {
+		fprintf(stderr, "Invalid options: -o and -n are mutually exclusive\n");
+		return 1;
+	}
+
 	if (use_cycle)
 		init_cycle();
 

index fc4fe91ee098..52a56599a543 100644
@@ -28,6 +28,7 @@
 #include <sys/time.h>
 #include <sys/poll.h>
 #include <limits.h>
+#include <err.h>
 
 #define DATASIZE 100
 

@@ -50,12 +51,6 @@ struct receiver_context {
 	int wakefd;
 };
 
-static void barf(const char *msg)
-{
-	fprintf(stderr, "%s (error: %s)\n", msg, strerror(errno));
-	exit(1);
-}
-
 static void fdpair(int fds[2])
 {
 	if (use_pipes) {

@@ -66,7 +61,7 @@ static void fdpair(int fds[2])
 			return;
 	}
 
-	barf(use_pipes ? "pipe()" : "socketpair()");
+	err(EXIT_FAILURE, use_pipes ? "pipe()" : "socketpair()");
 }
 
 /* Block until we're ready to go */

@@ -77,11 +72,11 @@ static void ready(int ready_out, int wakefd)
 
 	/* Tell them we're ready. */
 	if (write(ready_out, &dummy, 1) != 1)
-		barf("CLIENT: ready write");
+		err(EXIT_FAILURE, "CLIENT: ready write");
 
 	/* Wait for "GO" signal */
 	if (poll(&pollfd, 1, -1) != 1)
-		barf("poll");
+		err(EXIT_FAILURE, "poll");
 }
 
 /* Sender sprays loops messages down each file descriptor */

@@ -101,7 +96,7 @@ again:
 			ret = write(ctx->out_fds[j], data + done,
 				    sizeof(data)-done);
 			if (ret < 0)
-				barf("SENDER: write");
+				err(EXIT_FAILURE, "SENDER: write");
 			done += ret;
 			if (done < DATASIZE)
 				goto again;

@@ -131,7 +126,7 @@ static void *receiver(struct receiver_context* ctx)
 again:
 		ret = read(ctx->in_fds[0], data + done, DATASIZE - done);
 		if (ret < 0)
-			barf("SERVER: read");
+			err(EXIT_FAILURE, "SERVER: read");
 		done += ret;
 		if (done < DATASIZE)
 			goto again;

@@ -144,14 +139,14 @@ static pthread_t create_worker(void *ctx, void *(*func)(void *))
 {
 	pthread_attr_t attr;
 	pthread_t childid;
-	int err;
+	int ret;
 
 	if (!thread_mode) {
 		/* process mode */
 		/* Fork the receiver. */
 		switch (fork()) {
 		case -1:
-			barf("fork()");
+			err(EXIT_FAILURE, "fork()");
 			break;
 		case 0:
 			(*func) (ctx);

@@ -165,19 +160,17 @@ static pthread_t create_worker(void *ctx, void *(*func)(void *))
 	}
 
 	if (pthread_attr_init(&attr) != 0)
-		barf("pthread_attr_init:");
+		err(EXIT_FAILURE, "pthread_attr_init:");
 
 #ifndef __ia64__
 	if (pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN) != 0)
-		barf("pthread_attr_setstacksize");
+		err(EXIT_FAILURE, "pthread_attr_setstacksize");
 #endif
 
-	err = pthread_create(&childid, &attr, func, ctx);
-	if (err != 0) {
-		fprintf(stderr, "pthread_create failed: %s (%d)\n",
-			strerror(err), err);
-		exit(-1);
-	}
+	ret = pthread_create(&childid, &attr, func, ctx);
+	if (ret != 0)
+		err(EXIT_FAILURE, "pthread_create failed");
+
 	return childid;
 }
 

@@ -207,14 +200,14 @@ static unsigned int group(pthread_t *pth,
 			+ num_fds * sizeof(int));
 
 	if (!snd_ctx)
-		barf("malloc()");
+		err(EXIT_FAILURE, "malloc()");
 
 	for (i = 0; i < num_fds; i++) {
 		int fds[2];
 		struct receiver_context *ctx = malloc(sizeof(*ctx));
 
 		if (!ctx)
-			barf("malloc()");
+			err(EXIT_FAILURE, "malloc()");
 
 
 		/* Create the pipe between client and server */

@@ -281,7 +274,7 @@ int bench_sched_messaging(int argc, const char **argv,
 
 	pth_tab = malloc(num_fds * 2 * num_groups * sizeof(pthread_t));
 	if (!pth_tab)
-		barf("main:malloc()");
+		err(EXIT_FAILURE, "main:malloc()");
 
 	fdpair(readyfds);
 	fdpair(wakefds);

@@ -294,13 +287,13 @@ int bench_sched_messaging(int argc, const char **argv,
 	/* Wait for everyone to be ready */
 	for (i = 0; i < total_children; i++)
 		if (read(readyfds[0], &dummy, 1) != 1)
-			barf("Reading for readyfds");
+			err(EXIT_FAILURE, "Reading for readyfds");
 
 	gettimeofday(&start, NULL);
 
 	/* Kick them off */
 	if (write(wakefds[1], &dummy, 1) != 1)
-		barf("Writing to start them");
+		err(EXIT_FAILURE, "Writing to start them");
 
 	/* Reap them all */
 	for (i = 0; i < total_children; i++)