libbpf-tools: trace_helpers: add str_loadavg()

There are many tools read /proc/loadavg, this commit add a comment
function str_loadavg().

Signed-off-by: Rong Tao <[email protected]>

Author: Rtoax

libbpf-tools/biotop.c

@@ -301,24 +301,14 @@ static int read_stat(struct biotop_bpf *obj, struct data_t *datas, __u32 *count)
 
 static int print_stat(struct biotop_bpf *obj)
 {
-	FILE *f;
-	time_t t;
-	struct tm *tm;
-	char ts[16], buf[256];
+	char buf[256];
 	static struct data_t datas[OUTPUT_ROWS_LIMIT];
-	int n, i, err = 0, rows = OUTPUT_ROWS_LIMIT;
-
-	f = fopen("/proc/loadavg", "r");
-	if (f) {
-		time(&t);
-		tm = localtime(&t);
-		strftime(ts, sizeof(ts), "%H:%M:%S", tm);
-		memset(buf, 0, sizeof(buf));
-		n = fread(buf, 1, sizeof(buf), f);
-		if (n)
-			printf("%8s loadavg: %s\n", ts, buf);
-		fclose(f);
-	}
+	int i, err = 0, rows = OUTPUT_ROWS_LIMIT;
+
+	err = str_loadavg(buf, sizeof(buf), true);
+	if (!err)
+		printf("%s\n", buf);
+
 	printf("%-7s %-16s %1s %-3s %-3s %-8s %5s %7s %6s\n",
 	       "PID", "COMM", "D", "MAJ", "MIN", "DISK", "I/O", "Kbytes", "AVGms");
 

libbpf-tools/filetop.c

@@ -182,26 +182,13 @@ static int sort_column(const void *obj1, const void *obj2)
 
 static int print_stat(struct filetop_bpf *obj)
 {
-	FILE *f;
-	time_t t;
-	struct tm *tm;
-	char ts[16], buf[256];
+	char buf[256];
 	struct file_id key, *prev_key = NULL;
 	static struct file_stat values[OUTPUT_ROWS_LIMIT];
-	int n, i, err = 0, rows = 0;
+	int i, err = 0, rows = 0;
 	int fd = bpf_map__fd(obj->maps.entries);
 
-	f = fopen("/proc/loadavg", "r");
-	if (f) {
-		time(&t);
-		tm = localtime(&t);
-		strftime(ts, sizeof(ts), "%H:%M:%S", tm);
-		memset(buf, 0, sizeof(buf));
-		n = fread(buf, 1, sizeof(buf), f);
-		if (n)
-			printf("%8s loadavg: %s\n", ts, buf);
-		fclose(f);
-	}
+	printf("%s\n", str_loadavg(buf, sizeof(buf), true) ? "N/A" : buf);
 
 	printf("%-7s %-16s %-6s %-6s %-7s %-7s %1s %s\n",
 	       "TID", "COMM", "READS", "WRITES", "R_Kb", "W_Kb", "T", "FILE");

libbpf-tools/oomkill.c

@@ -60,25 +60,17 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 
 static int handle_event(void *ctx, void *data, size_t len)
 {
-	FILE *f;
 	char buf[256];
-	int n = 0;
 	struct tm *tm;
 	char ts[32];
 	time_t t;
 	struct data_t *e = data;
 
-	f = fopen("/proc/loadavg", "r");
-	if (f) {
-		memset(buf, 0, sizeof(buf));
-		n = fread(buf, 1, sizeof(buf), f);
-		fclose(f);
-	}
 	time(&t);
 	tm = localtime(&t);
 	strftime(ts, sizeof(ts), "%H:%M:%S", tm);
 
-	if (n)
+	if (!str_loadavg(buf, sizeof(buf), false))
 		printf("%s Triggered by PID %d (\"%s\"), OOM kill of PID %d (\"%s\"), %lld pages, loadavg: %s",
 			ts, e->fpid, e->fcomm, e->tpid, e->tcomm, e->pages, buf);
 	else

libbpf-tools/slabratetop.c

@@ -169,26 +169,13 @@ static int sort_column(const void *obj1, const void *obj2)
 
 static int print_stat(struct slabratetop_bpf *obj)
 {
-	FILE *f;
-	time_t t;
-	struct tm *tm;
-	char ts[16], buf[256];
+	char buf[256];
 	char *key, **prev_key = NULL;
 	static struct slabrate_info values[OUTPUT_ROWS_LIMIT];
-	int n, i, err = 0, rows = 0;
+	int i, err = 0, rows = 0;
 	int fd = bpf_map__fd(obj->maps.slab_entries);
 
-	f = fopen("/proc/loadavg", "r");
-	if (f) {
-		time(&t);
-		tm = localtime(&t);
-		strftime(ts, sizeof(ts), "%H:%M:%S", tm);
-		memset(buf, 0 , sizeof(buf));
-		n = fread(buf, 1, sizeof(buf), f);
-		if (n)
-			printf("%8s loadavg: %s\n", ts, buf);
-		fclose(f);
-	}
+	printf("%s\n", str_loadavg(buf, sizeof(buf), true) ? "N/A" : buf);
 
 	printf("%-32s %6s %10s\n", "CACHE", "ALLOCS", "BYTES");
 

libbpf-tools/tcptop.c

@@ -214,13 +214,10 @@ static int sort_column(const void *obj1, const void *obj2)
 
 static int print_stat(struct tcptop_bpf *obj)
 {
-	FILE *f;
-	time_t t;
-	struct tm *tm;
-	char ts[16], buf[256];
+	char buf[256];
 	struct ip_key_t key, *prev_key = NULL;
 	static struct info_t infos[OUTPUT_ROWS_LIMIT];
-	int n, i, err = 0;
+	int i, err = 0;
 	int fd = bpf_map__fd(obj->maps.ip_map);
 	int rows = 0;
 	bool ipv6_header_printed = false;
@@ -232,17 +229,7 @@ static int print_stat(struct tcptop_bpf *obj)
 	close(pid_max_fd);
 
 	if (!no_summary) {
-		f = fopen("/proc/loadavg", "r");
-		if (f) {
-			time(&t);
-			tm = localtime(&t);
-			strftime(ts, sizeof(ts), "%H:%M:%S", tm);
-			memset(buf, 0, sizeof(buf));
-			n = fread(buf, 1, sizeof(buf), f);
-			if (n)
-				printf("%8s loadavg: %s\n", ts, buf);
-			fclose(f);
-		}
+		printf("%s\n", str_loadavg(buf, sizeof(buf), true) ? "N/A" : buf);
 	}
 
 	while (1) {

libbpf-tools/trace_helpers.c

@@ -1311,3 +1311,43 @@ int str_to_long(const char *src, void *dest)
 
 	return errno;
 }
+
+/**
+ * If @ts_pfx is true, the timestamp prefix will added.
+ */
+int str_loadavg(char *buf, size_t buf_len, bool ts_pfx)
+{
+	int n, err = 0;
+	time_t t;
+	struct tm *tm;
+	char ts[16], avg[64];
+	FILE *f;
+
+	if (!buf || buf_len == 0)
+		return -EINVAL;
+
+	f = fopen("/proc/loadavg", "r");
+	if (!f) {
+		return -errno;
+	}
+
+	n = fread(avg, 1, sizeof(avg), f);
+	if (!n) {
+		err = -errno;
+		goto cleanup;
+	}
+
+	memset(buf, 0, buf_len);
+	if (ts_pfx) {
+		time(&t);
+		tm = localtime(&t);
+		strftime(ts, sizeof(ts), "%H:%M:%S", tm);
+		snprintf(buf, buf_len, "%8s loadavg: %s", ts, avg);
+	} else {
+		snprintf(buf, buf_len, "loadavg: %s", avg);
+	}
+
+cleanup:
+	fclose(f);
+	return err;
+}

libbpf-tools/trace_helpers.h

@@ -121,4 +121,7 @@ int str_to_int(const char *src, void *dest);
 /* converts a string to a long integer */
 int str_to_long(const char *src, void *dest);
 
+/* get loadavg string */
+int str_loadavg(char *buf, size_t buf_len, bool ts_pfx);
+
 #endif /* __TRACE_HELPERS_H */