alsactl: add --nice and --sched-idle options

The state management can run at low priority, add --nice and --sched-idle
options to set the scheduler.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

4 files changed, 49 insertions, 3 deletions

diff --git a/alsactl/Makefile.am b/alsactl/Makefile.am
index 2a439e9..0659b28 100644
--- a/alsactl/Makefile.am
+++ b/alsactl/Makefile.am
@@ -8,7 +8,7 @@ endif
 EXTRA_DIST=alsactl.1 alsactl_init.xml
 
 alsactl_SOURCES=alsactl.c state.c lock.c utils.c init_parse.c daemon.c
-alsactl_CFLAGS=$(AM_CFLAGS) -DSYS_ASOUNDRC=\"$(ASOUND_STATE_DIR)/asound.state\" -DSYS_PIDFILE=\"$(ALSACTL_PIDFILE_DIR)/alsactl.pid\"
+alsactl_CFLAGS=$(AM_CFLAGS) -D__USE_GNU -DSYS_ASOUNDRC=\"$(ASOUND_STATE_DIR)/asound.state\" -DSYS_PIDFILE=\"$(ALSACTL_PIDFILE_DIR)/alsactl.pid\"
 noinst_HEADERS=alsactl.h list.h init_sysdeps.c init_utils_string.c init_utils_run.c init_sysfs.c
 
 dist_udevrules_DATA = \
diff --git a/alsactl/alsa-state.service.in b/alsactl/alsa-state.service.in
index 119be1b..fc9914b 100644
--- a/alsactl/alsa-state.service.in
+++ b/alsactl/alsa-state.service.in
@@ -7,5 +7,5 @@ Conflicts=shutdown.target
 
 [Service]
 Type=simple
-ExecStart=-@sbindir@/alsactl -s rdaemon
+ExecStart=-@sbindir@/alsactl -s -n 19 -c rdaemon
 ExecStop=-@sbindir@/alsactl -s rkill save_and_quit
diff --git a/alsactl/alsactl.1 b/alsactl/alsactl.1
index 36bd8b5..45ac8a6 100644
--- a/alsactl/alsactl.1
+++ b/alsactl/alsactl.1
@@ -115,6 +115,14 @@ Run the task in background.
 \fI\-s, \-\-syslog\fP
 Use syslog for messages.
 
+.TP
+\fI\-n, \-\-nice\fP
+Set the process priority (see 'man nice')
+
+.TP
+\fI\-c, \-\-sched-idle\fP
+Set the process scheduling policy to idle (SCHED_IDLE).
+
 .SH FILES
 \fI/var/lib/alsa/asound.state\fP (or whatever file you specify with the
 \fB\-f\fP flag) is used to store current settings for your
diff --git a/alsactl/alsactl.c b/alsactl/alsactl.c
index f00cfff..75baad8 100644
--- a/alsactl/alsactl.c
+++ b/alsactl/alsactl.c
@@ -28,6 +28,7 @@
 #include <assert.h>
 #include <errno.h>
 #include <syslog.h>
+#include <sched.h>
 #include <alsa/asoundlib.h>
 #include "alsactl.h"
 
@@ -87,6 +88,8 @@ static struct arg args[] = {
 { 0, NULL, "  (default " DATADIR "/init/00main)" },
 { 'b', "background", "run daemon in background" },
 { 's', "syslog", "use syslog for messages" },
+{ INTARG | 'n', "nice", "set the process priority (see 'man nice')" },
+{ 'c', "sched-idle", "set the process scheduling policy to idle (SCHED_IDLE)" },
 { HEADER, NULL, "Available commands:" },
 { CARDCMD, "store", "save current driver setup for one or each soundcards" },
 { EMPCMD, NULL, "  to configuration file" },
@@ -140,6 +143,25 @@ static void help(void)
 	}
 }
 
+#define NO_NICE (-100000)
+
+static void do_nice(int use_nice, int sched_idle)
+{
+	struct sched_param sched_param;
+
+	if (use_nice != NO_NICE && nice(use_nice) < 0)
+		error("nice(%i): %s", use_nice, strerror(errno));
+	if (sched_idle) {
+		if (sched_getparam(0, &sched_param) >= 0) {
+			sched_param.sched_priority = 0;
+			if (!sched_setscheduler(0, SCHED_RR, &sched_param))
+				error("sched_setparam failed: %s", strerror(errno));
+		} else {
+			error("sched_getparam failed: %s", strerror(errno));
+		}
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	static const char *const devfiles[] = {
@@ -160,6 +182,8 @@ int main(int argc, char *argv[])
 	int period = 5*60;
 	int background = 0;
 	int daemoncmd = 0;
+	int use_nice = NO_NICE;
+	int sched_idle = 0;
 	struct arg *a;
 	struct option *o;
 	int i, j, k, res;
@@ -251,6 +275,16 @@ int main(int argc, char *argv[])
 		case 's':
 			use_syslog = 1;
 			break;
+		case 'n':
+			use_nice = atoi(optarg);
+			if (use_nice < -20)
+				use_nice = -20;
+			else if (use_nice > 19)
+				use_nice = 19;
+			break;
+		case 'c':
+			sched_idle = 1;
+			break;
 		case 'd':
 			debugflag = 1;
 			break;
@@ -268,6 +302,7 @@ int main(int argc, char *argv[])
 		}
 	}
 	free(short_option);
+	short_option = NULL;
 	free(long_option);
 	long_option = NULL;
 	if (argc - optind <= 0) {
@@ -317,11 +352,14 @@ int main(int argc, char *argv[])
 		if (removestate)
 			remove(statefile);
 		res = load_state(cfgfile, initfile, cardname, init_fallback);
-		if (!strcmp(cmd, "rdaemon"))
+		if (!strcmp(cmd, "rdaemon")) {
+			do_nice(use_nice, sched_idle);
 			res = state_daemon(cfgfile, cardname, period, pidfile);
+		}
 		if (!strcmp(cmd, "nrestore"))
 			res = state_daemon_kill(pidfile, "rescan");
 	} else if (!strcmp(cmd, "daemon")) {
+		do_nice(use_nice, sched_idle);
 		res = state_daemon(cfgfile, cardname, period, pidfile);
 	} else if (!strcmp(cmd, "kill")) {
 		res = state_daemon_kill(pidfile, cardname);