chrt: add --reset-on-fork

This new option allows to set SCHED_RESET_ON_FORK flag for FIFO and RR
policies.

Example:

	$ chrt --fifo --reset-on-fork 1 /bin/bash

	$ schedutils/chrt --pid $$
	pid 31579's current scheduling policy: SCHED_FIFO|SCHED_RESET_ON_FORK
	pid 31579's current scheduling priority: 1

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/schedutils/chrt.1 b/schedutils/chrt.1
index 06c58b479470a9da525787a075521cae96ebbf20..9016cfef0c32444369c684adb367fdd6ddb4683e 100644 (file)
--- a/schedutils/chrt.1
+++ b/schedutils/chrt.1
@@ -55,6 +55,11 @@ The
 policy is supported since Linux 2.6.16. The
 .BR SCHED_IDLE
 policy is supported since Linux 2.6.23.
+.PP
+The
+.BR SCHED_RESET_ON_FORK
+flag for policies SCHED_RR and SCHED_FIFO is supported
+since Linux 2.6.31.
 .SH OPTIONS
 .TP
 .B -p, --pid
@@ -69,6 +74,15 @@ set scheduling policy to
 set scheduling policy to
 .BR SCHED_FIFO
 .TP
+.B -R, --reset-on-fork
+add
+.B SCHED_RESET_ON_FORK
+flag to the
+.B SCHED_FIFO
+or
+.B SCHED_RR
+scheduling policy (Linux specific)
+.TP
 .B -i, --idle
 set schedulng policy to
 .BR SCHED_IDLE

diff --git a/schedutils/chrt.c b/schedutils/chrt.c
index 6629c2e80d7d0f8734cda1ea22b8d1a08bdc3ea0..0ff9b9bb49dfae441a25fb0e311e351dc8dc2326 100644 (file)
--- a/schedutils/chrt.c
+++ b/schedutils/chrt.c
@@ -66,6 +66,8 @@ static void show_usage(int rc)
        "  -i | --idle          set policy to SCHED_IDLE\n"
        "  -o | --other         set policy to SCHED_OTHER\n"
        "  -r | --rr            set policy to SCHED_RR (default)\n"
+       "\nScheduling flags:\n"
+       "  -R | --reset-on-fork set SCHED_RESET_ON_FORK for FIFO or RR\n"
        "\nOptions:\n"
        "  -h | --help          display this help\n"
        "  -p | --pid           operate on existing given pid\n"
@@ -161,7 +163,7 @@ static void show_min_max(void)
 
 int main(int argc, char *argv[])
 {
-       int i, policy = SCHED_RR, priority = 0, verbose = 0;
+       int i, policy = SCHED_RR, priority = 0, verbose = 0, policy_flag = 0;
        struct sched_param sp;
        pid_t pid = -1;
 
@@ -174,6 +176,7 @@ int main(int argc, char *argv[])
                { "max",        0, NULL, 'm' },
                { "other",      0, NULL, 'o' },
                { "rr",         0, NULL, 'r' },
+               { "reset-on-fork", 0, NULL, 'R' },
                { "verbose",    0, NULL, 'v' },
                { "version",    0, NULL, 'V' },
                { NULL,         0, NULL, 0 }
@@ -183,7 +186,7 @@ int main(int argc, char *argv[])
        bindtextdomain(PACKAGE, LOCALEDIR);
        textdomain(PACKAGE);
 
-       while((i = getopt_long(argc, argv, "+bfiphmorvV", longopts, NULL)) != -1)
+       while((i = getopt_long(argc, argv, "+bfiphmoRrvV", longopts, NULL)) != -1)
        {
                int ret = EXIT_FAILURE;
 
@@ -196,6 +199,9 @@ int main(int argc, char *argv[])
                case 'f':
                        policy = SCHED_FIFO;
                        break;
+               case 'R':
+                       policy_flag |= SCHED_RESET_ON_FORK;
+                       break;
                case 'i':
 #ifdef SCHED_IDLE
                        policy = SCHED_IDLE;
@@ -243,6 +249,14 @@ int main(int argc, char *argv[])
        if (errno)
                err(EXIT_FAILURE, _("failed to parse priority"));
 
+       /* sanity check */
+       if ((policy_flag & SCHED_RESET_ON_FORK) &&
+           !(policy == SCHED_FIFO || policy == SCHED_RR))
+               errx(EXIT_FAILURE, _("SCHED_RESET_ON_FORK flag is suppoted for "
+                               "SCHED_FIFO and SCHED_RR policies only"));
+
+       policy |= policy_flag;
+
        if (pid == -1)
                pid = 0;
        sp.sched_priority = priority;