chrt: use sched_setattr() if available

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

diff --git a/configure.ac b/configure.ac
index 83b76ae1f9b65fd8a62701e0f667a544c1cb5e43..2c1ffbc057267c05c992b95fb16caf535fb378a6 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -359,6 +359,7 @@ AC_CHECK_FUNCS([ \
        scandirat \
        setresgid \
        setresuid \
+       sched_setattr \
        sigqueue \
        srandom \
        strnchr \
@@ -1776,6 +1777,10 @@ UL_BUILD_INIT([chrt], [check])
 UL_REQUIRES_BUILD([chrt], [schedutils])
 AM_CONDITIONAL([BUILD_CHRT], [test "x$build_chrt" = xyes])
 
+AS_IF([test "x$build_chrt" = xyes], [
+       UL_CHECK_SYSCALL([sched_setattr])
+])
+
 
 AC_ARG_ENABLE([wall],
   AS_HELP_STRING([--disable-wall], [do not build wall]),

diff --git a/schedutils/chrt.c b/schedutils/chrt.c
index 9be88b00c809bcba1b97704dcd53ad322ffab0e6..ee08821f4036a975f62d9a679eed3ec71097288f 100644 (file)
--- a/schedutils/chrt.c
+++ b/schedutils/chrt.c
@@ -52,6 +52,42 @@
 #define SCHED_RESET_ON_FORK 0x40000000
 #endif
 
+#if defined (__linux__) && !defined(HAVE_SCHED_SETATTR)
+# include <sys/syscall.h>
+#endif
+
+#if defined (__linux__) && !defined(HAVE_SCHED_SETATTR) && defined(SYS_sched_setattr)
+# define HAVE_SCHED_SETATTR
+
+struct sched_attr {
+       uint32_t size;
+       uint32_t sched_policy;
+       uint64_t sched_flags;
+
+       /* SCHED_NORMAL, SCHED_BATCH */
+       int32_t sched_nice;
+
+       /* SCHED_FIFO, SCHED_RR */
+       uint32_t sched_priority;
+
+       /* SCHED_DEADLINE (nsec) */
+       uint64_t sched_runtime;
+       uint64_t sched_deadline;
+       uint64_t sched_period;
+};
+
+static int sched_setattr(pid_t pid, const struct sched_attr *attr, unsigned int flags)
+{
+       return syscall(SYS_sched_setattr, pid, attr, flags);
+}
+
+static int sched_getattr(pid_t pid, struct sched_attr *attr, unsigned int size, unsigned int flags)
+{
+       return syscall(SYS_sched_getattr, pid, attr, size, flags);
+}
+#endif /* !HAVE_SCHED_SETATTR */
+
+
 /* control struct */
 struct chrt_ctl {
        pid_t   pid;
@@ -224,10 +260,36 @@ static void show_min_max(void)
        }
 }
 
-static void set_sched(struct chrt_ctl *ctl)
+#ifndef HAVE_SCHED_SETATTR
+static int set_sched_one(struct chrt_ctl *ctl, pid_t pid)
 {
        struct sched_param sp = { .sched_priority = ctl->priority };
+       int policy = ctl->policy;
 
+# ifdef SCHED_RESET_ON_FORK
+       if (ctl->reset_on_fork)
+               policy |= SCHED_RESET_ON_FORK;
+# endif
+       return sched_setscheduler(pid, policy, &sp);
+}
+
+#else /* !HAVE_SCHED_SETATTR */
+static int set_sched_one(struct chrt_ctl *ctl, pid_t pid)
+{
+       struct sched_attr sa = {
+               .sched_policy   = ctl->policy,
+               .sched_priority = ctl->priority
+       };
+# ifdef SCHED_RESET_ON_FORK
+       if (ctl->reset_on_fork)
+               sa.sched_flags |= SCHED_RESET_ON_FORK;
+# endif
+       return sched_setattr(pid, &sa, 0);
+}
+#endif /* HAVE_SCHED_SETATTR */
+
+static void set_sched(struct chrt_ctl *ctl)
+{
        if (ctl->all_tasks) {
                pid_t tid;
                struct proc_tasks *ts = proc_open_tasks(ctl->pid);
@@ -236,12 +298,12 @@ static void set_sched(struct chrt_ctl *ctl)
                        err(EXIT_FAILURE, _("cannot obtain the list of tasks"));
 
                while (!proc_next_tid(ts, &tid))
-                       if (sched_setscheduler(tid, ctl->policy, &sp) == -1)
+                       if (set_sched_one(ctl, tid) == -1)
                                err(EXIT_FAILURE, _("failed to set tid %d's policy"), tid);
 
                proc_close_tasks(ts);
 
-       } else if (sched_setscheduler(ctl->pid, ctl->policy, &sp) == -1)
+       } else if (set_sched_one(ctl, ctl->pid) == -1)
                err(EXIT_FAILURE, _("failed to set pid %d's policy"), ctl->pid);
 
        ctl->altered = 1;
@@ -338,14 +400,11 @@ int main(int argc, char **argv)
        ctl->priority = strtos32_or_err(argv[optind], _("invalid priority argument"));
 
 #ifdef SCHED_RESET_ON_FORK
-       if (ctl->reset_on_fork) {
+       if (ctl->reset_on_fork)
                if (ctl->policy != SCHED_FIFO && ctl->policy != SCHED_RR)
                        errx(EXIT_FAILURE, _("SCHED_RESET_ON_FORK flag is supported for "
                                             "SCHED_FIFO and SCHED_RR policies only"));
-               ctl->policy |= SCHED_RESET_ON_FORK;
-       }
 #endif
-
        if (ctl->pid == -1)
                ctl->pid = 0;