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-rw-r--r--NEWS1
-rw-r--r--configure.ac2
-rw-r--r--src/Main.cxx5
-rw-r--r--src/output/OutputThread.cxx2
-rw-r--r--src/thread/Slack.hxx54
5 files changed, 64 insertions, 0 deletions
diff --git a/NEWS b/NEWS
index dd08e4b24..7db9cd4da 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,7 @@ ver 0.19 (not yet released)
* threads:
- the update thread runs at "idle" priority
- the output thread runs at "real-time" priority
+ - increase kernel timer slack on Linux
- name each thread (for debugging)
* new resampler option using libsoxr
diff --git a/configure.ac b/configure.ac
index 0da4eb645..80e50191e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -184,6 +184,8 @@ AC_SEARCH_LIBS([exp], [m],,
AC_CHECK_HEADERS(locale.h)
AC_CHECK_HEADERS(valgrind/memcheck.h)
+AC_CHECK_HEADERS([sys/prctl.h], AC_CHECK_FUNCS([prctl]))
+
AC_CHECK_LIB([pthread], [pthread_setname_np],
[have_pthread_setname_np=yes],
[have_pthread_setname_np=no])
diff --git a/src/Main.cxx b/src/Main.cxx
index f8f7a6545..ab70c875c 100644
--- a/src/Main.cxx
+++ b/src/Main.cxx
@@ -60,6 +60,7 @@
#include "util/Error.hxx"
#include "util/Domain.hxx"
#include "thread/Id.hxx"
+#include "thread/Slack.hxx"
#include "config/ConfigGlobal.hxx"
#include "config/ConfigData.hxx"
#include "config/ConfigDefaults.hxx"
@@ -523,6 +524,10 @@ int mpd_main(int argc, char *argv[])
win32_app_started();
#endif
+ /* the MPD frontend does not care about timer slack; set it to
+ a huge value to allow the kernel to reduce CPU wakeups */
+ SetThreadTimerSlackMS(100);
+
/* run the main loop */
main_loop->Run();
diff --git a/src/output/OutputThread.cxx b/src/output/OutputThread.cxx
index 05d9468b4..a7fb2b87f 100644
--- a/src/output/OutputThread.cxx
+++ b/src/output/OutputThread.cxx
@@ -30,6 +30,7 @@
#include "MusicPipe.hxx"
#include "MusicChunk.hxx"
#include "thread/Util.hxx"
+#include "thread/Slack.hxx"
#include "thread/Name.hxx"
#include "system/FatalError.hxx"
#include "util/Error.hxx"
@@ -561,6 +562,7 @@ AudioOutput::Task()
FormatThreadName("output:%s", name);
SetThreadRealtime();
+ SetThreadTimerSlackUS(100);
mutex.lock();
diff --git a/src/thread/Slack.hxx b/src/thread/Slack.hxx
new file mode 100644
index 000000000..66b2254a4
--- /dev/null
+++ b/src/thread/Slack.hxx
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_THREAD_SLACK_HXX
+#define MPD_THREAD_SLACK_HXX
+
+#ifdef HAVE_PRCTL
+#include <sys/prctl.h>
+#endif
+
+/**
+ * Set the current thread's timer slack to the specified number of
+ * nanoseconds (requires Linux 2.6.28). This allows the kernel to
+ * merge multiple wakeups, which is a trick to save energy.
+ */
+static inline void
+SetThreadTimerSlackNS(unsigned long slack_ns)
+{
+#if defined(HAVE_PRCTL) && defined(PR_SET_TIMERSLACK)
+ prctl(PR_SET_TIMERSLACK, slack_ns, 0, 0, 0);
+#else
+ (void)slack_ns;
+#endif
+}
+
+static inline void
+SetThreadTimerSlackUS(unsigned long slack_us)
+{
+ SetThreadTimerSlackNS(slack_us * 1000ul);
+}
+
+static inline void
+SetThreadTimerSlackMS(unsigned long slack_ms)
+{
+ SetThreadTimerSlackNS(slack_ms * 1000000ul);
+}
+
+#endif