perf bench: Make the mem/memcpy tests more user-friendly

mem-memcpy.c uses perf event system calls to obtain CPU clocks.
And it suddenly dies with BUG_ON() when it running on Linux
doesn't support perf event.

Also fail at calloc() can occur easily when too large
length is passed. Fail of calloc() causes sudden death
with assert().

These behaviours are not friendly. So I fixed the treating of
errors.
Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1258688237-3797-1-git-send-email-mitake@dcl.info.waseda.ac.jp>
[ v2: improved a few small details ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/bench/mem-memcpy.c

@@ -22,9 +22,10 @@
 
 #define K 1024
 
-static const char *length_str = "1MB";
-static const char *routine    = "default";
-static int use_clock = 0;
+static const char	*length_str	= "1MB";
+static const char	*routine	= "default";
+static int		use_clock	= 0;
+static int		clock_fd;
 
 static const struct option options[] = {
 	OPT_STRING('l', "length", &length_str, "1MB",
@@ -57,17 +58,19 @@ static const char * const bench_mem_memcpy_usage[] = {
 	NULL
 };
 
-static int clock_fd;
-
 static struct perf_event_attr clock_attr = {
-	.type = PERF_TYPE_HARDWARE,
-	.config = PERF_COUNT_HW_CPU_CYCLES
+	.type		= PERF_TYPE_HARDWARE,
+	.config		= PERF_COUNT_HW_CPU_CYCLES
 };
 
 static void init_clock(void)
 {
 	clock_fd = sys_perf_event_open(&clock_attr, getpid(), -1, -1, 0);
-	BUG_ON(clock_fd < 0);
+
+	if (clock_fd < 0 && errno == ENOSYS)
+		die("No CONFIG_PERF_EVENTS=y kernel support configured?\n");
+	else
+		BUG_ON(clock_fd < 0);
 }
 
 static u64 get_clock(void)
@@ -104,7 +107,8 @@ int bench_mem_memcpy(int argc, const char **argv,
 	tv_diff.tv_sec = 0;
 	tv_diff.tv_usec = 0;
 	length = (size_t)perf_atoll((char *)length_str);
-	if ((long long int)length <= 0) {
+
+	if ((s64)length <= 0) {
 		fprintf(stderr, "Invalid length:%s\n", length_str);
 		return 1;
 	}
@@ -124,9 +128,12 @@ int bench_mem_memcpy(int argc, const char **argv,
 	}
 
 	dst = calloc(length, sizeof(char));
-	assert(dst);
+	if (!dst)
+		die("memory allocation failed - maybe length is too large?\n");
+
 	src = calloc(length, sizeof(char));
-	assert(src);
+	if (!src)
+		die("memory allocation failed - maybe length is too large?\n");
 
 	if (bench_format == BENCH_FORMAT_DEFAULT) {
 		printf("# Copying %s Bytes from %p to %p ...\n\n",
@@ -136,8 +143,9 @@ int bench_mem_memcpy(int argc, const char **argv,
 	if (use_clock) {
 		init_clock();
 		clock_start = get_clock();
-	} else
+	} else {
 		BUG_ON(gettimeofday(&tv_start, NULL));
+	}
 
 	routines[i].fn(dst, src, length);
 
@@ -176,9 +184,8 @@ int bench_mem_memcpy(int argc, const char **argv,
 			printf("%lf\n", bps);
 		break;
 	default:
-		/* reaching here is something disaster */
-		fprintf(stderr, "Unknown format:%d\n", bench_format);
-		exit(1);
+		/* reaching this means there's some disaster: */
+		die("unknown format: %d\n", bench_format);
 		break;
 	}