From 8474fd7c62712470465800ddccd6ea291d04151e Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 19 Jun 2009 04:19:08 +0200
Subject: core: ask RealtimeKit for RT scheduling

---
 src/pulsecore/core-util.c | 96 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 78 insertions(+), 18 deletions(-)

(limited to 'src/pulsecore/core-util.c')

diff --git a/src/pulsecore/core-util.c b/src/pulsecore/core-util.c
index a71ba0b0..1fdd1890 100644
--- a/src/pulsecore/core-util.c
+++ b/src/pulsecore/core-util.c
@@ -50,6 +50,10 @@
 
 #ifdef HAVE_SCHED_H
 #include <sched.h>
+
+#if defined(__linux__) && !defined(SCHED_RESET_ON_FORK)
+#define SCHED_RESET_ON_FORK 0x40000000
+#endif
 #endif
 
 #ifdef HAVE_SYS_RESOURCE_H
@@ -92,6 +96,10 @@
 #include <xlocale.h>
 #endif
 
+#ifdef HAVE_DBUS
+#include "rtkit.h"
+#endif
+
 #include <pulse/xmalloc.h>
 #include <pulse/util.h>
 #include <pulse/utf8.h>
@@ -552,16 +560,68 @@ char *pa_strlcpy(char *b, const char *s, size_t l) {
     return b;
 }
 
+static int set_scheduler(int rtprio) {
+    struct sched_param sp;
+    int r;
+#ifdef HAVE_DBUS
+    DBusError error;
+    DBusConnection *bus;
+
+    dbus_error_init(&error);
+#endif
+
+    pa_zero(sp);
+    sp.sched_priority = rtprio;
+
+#ifdef SCHED_RESET_ON_FORK
+    if ((r = pthread_setschedparam(pthread_self(), SCHED_RR|SCHED_RESET_ON_FORK, &sp)) == 0) {
+        pa_log_debug("SCHED_RR|SCHED_RESET_ON_FORK worked.");
+        return 0;
+    }
+#endif
+
+    if ((r = pthread_setschedparam(pthread_self(), SCHED_RR, &sp)) == 0) {
+        pa_log_debug("SCHED_RR worked.");
+        return 0;
+    }
+
+#ifdef HAVE_DBUS
+    /* Try to talk to RealtimeKit */
+
+    if (!(bus = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) {
+        pa_log("Failed to connect to system bus: %s\n", error.message);
+        dbus_error_free(&error);
+        errno = -EIO;
+        return -1;
+    }
+
+    r = rtkit_make_realtime(bus, 0, rtprio);
+    dbus_connection_unref(bus);
+
+    if (r >= 0) {
+        pa_log_debug("RealtimeKit worked.");
+        return 0;
+    }
+
+    errno = -r;
+#else
+    errno = r;
+#endif
+
+    return -1;
+}
+
 /* Make the current thread a realtime thread, and acquire the highest
  * rtprio we can get that is less or equal the specified parameter. If
  * the thread is already realtime, don't do anything. */
 int pa_make_realtime(int rtprio) {
 
 #ifdef _POSIX_PRIORITY_SCHEDULING
-    struct sched_param sp;
     int r, policy;
+    struct sched_param sp;
+    int rtprio_try;
 
-    memset(&sp, 0, sizeof(sp));
+    pa_zero(sp);
     policy = 0;
 
     if ((r = pthread_getschedparam(pthread_self(), &policy, &sp)) != 0) {
@@ -569,29 +629,29 @@ int pa_make_realtime(int rtprio) {
         return -1;
     }
 
-    if (policy == SCHED_FIFO && sp.sched_priority >= rtprio) {
-        pa_log_info("Thread already being scheduled with SCHED_FIFO with priority %i.", sp.sched_priority);
+#ifdef SCHED_RESET_ON_FORK
+    policy &= ~SCHED_RESET_ON_FORK;
+#endif
+
+    if ((policy == SCHED_FIFO || policy == SCHED_RR) && sp.sched_priority >= rtprio) {
+        pa_log_info("Thread already being scheduled with SCHED_FIFO/SCHED_RR with priority %i.", sp.sched_priority);
         return 0;
     }
 
-    sp.sched_priority = rtprio;
-    if ((r = pthread_setschedparam(pthread_self(), SCHED_FIFO, &sp)) != 0) {
-
-        while (sp.sched_priority > 1) {
-            sp.sched_priority --;
+    if (set_scheduler(rtprio) >= 0) {
+        pa_log_info("Successfully enabled SCHED_RR scheduling for thread, with priority %i.", rtprio);
+        return 0;
+    }
 
-            if ((r = pthread_setschedparam(pthread_self(), SCHED_FIFO, &sp)) == 0) {
-                pa_log_info("Successfully enabled SCHED_FIFO scheduling for thread, with priority %i, which is lower than the requested %i.", sp.sched_priority, rtprio);
-                return 0;
-            }
+    for (rtprio_try = rtprio-1; rtprio_try >= 1; rtprio_try--) {
+        if (set_scheduler(rtprio_try)) {
+            pa_log_info("Successfully enabled SCHED_RR scheduling for thread, with priority %i, which is lower than the requested %i.", rtprio_try, rtprio);
+            return 0;
         }
-
-        pa_log_warn("pthread_setschedparam(): %s", pa_cstrerror(r));
-        return -1;
     }
 
-    pa_log_info("Successfully enabled SCHED_FIFO scheduling for thread, with priority %i.", sp.sched_priority);
-    return 0;
+    pa_log_warn("Failed to acquire real-time scheduling: %s", pa_cstrerror(r));
+    return -1;
 #else
 
     errno = ENOTSUP;
-- 
cgit