nvme: add delay option for nvme top

This is to monitor the system changes.

Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>

Author: ikegami-t

nvme.c

@@ -191,6 +191,7 @@ const char *output_format = "Output format: normal|binary";
 const char *timeout = "timeout value, in milliseconds";
 const char *verbose = "Increase output verbosity";
 const char *dry_run = "show command instead of sending";
+const char *delay = "iterative delay as SECS [.TENTHS]";
 
 static const char *app_tag = "app tag for end-to-end PI";
 static const char *app_tag_mask = "app tag mask for end-to-end PI";
@@ -262,6 +263,7 @@ struct nvme_config nvme_cfg = {
 	.output_format = "normal",
 	.output_format_ver = 1,
 	.timeout = NVME_DEFAULT_IOCTL_TIMEOUT,
+	.delay = 0,
 };
 
 static void *mmap_registers(struct nvme_transport_handle *hdl, bool writable);
@@ -11011,6 +11013,29 @@ void register_extension(struct plugin *plugin)
 	nvme.extensions->tail = plugin;
 }
 
+static bool handle_delay(int err)
+{
+	struct timespec ts;
+	double delay_f;
+	double delay_i;
+
+	if (err || !nvme_cfg.delay)
+		return false;
+
+	delay_f = modf(nvme_cfg.delay, &delay_i);
+	ts.tv_sec = delay_i;
+	ts.tv_nsec = delay_f * 1000000000;
+	err = pselect(0, NULL, NULL, NULL, &ts, NULL);
+	if (err < 0)
+		return false;
+
+	err = system("clear");
+	if (err < 0)
+		return false;
+
+	return true;
+}
+
 int main(int argc, char **argv)
 {
 	int err;
@@ -11026,9 +11051,11 @@ int main(int argc, char **argv)
 	if (err)
 		return err;
 
-	err = handle_plugin(argc - 1, &argv[1], nvme.extensions);
-	if (err == -ENOTTY)
-		general_help(&builtin, NULL);
+	do {
+		err = handle_plugin(argc - 1, &argv[1], nvme.extensions);
+		if (err == -ENOTTY)
+			general_help(&builtin, NULL);
+	} while (handle_delay(err));
 
 	return err ? 1 : 0;
 }

nvme.h

@@ -59,6 +59,7 @@ struct nvme_config {
 	bool dry_run;
 	bool no_retries;
 	unsigned int output_format_ver;
+	double delay;
 };
 
 /*
@@ -76,6 +77,7 @@ struct nvme_config {
 			 "disable retry logic on errors\n"),                           \
 		OPT_UINT("output-format-version", 0, &nvme_cfg.output_format_ver,      \
 			 "output format version: 1|2"),                                \
+		OPT_DOUBLE("delay",      'd', &nvme_cfg.delay,         delay), \
 		OPT_END()                                                              \
 	}
 
@@ -109,6 +111,7 @@ extern const char *output_format;
 extern const char *timeout;
 extern const char *verbose;
 extern const char *dry_run;
+extern const char *delay;
 extern struct nvme_config nvme_cfg;
 
 int validate_output_format(const char *format, nvme_print_flags_t *flags);