3 files changed, 75 insertions, 0 deletions
diff --git a/sysdeps/nptl/pthreadP.h b/sysdeps/nptl/pthreadP.h
index 601db4ff2b..39af275c25 100644
--- a/sysdeps/nptl/pthreadP.h
+++ b/sysdeps/nptl/pthreadP.h
@@ -33,6 +33,7 @@
 #include <kernel-features.h>
 #include <errno.h>
 #include <internal-signals.h>
+#include <pthread_mutex_backoff.h>
 #include "pthread_mutex_conf.h"
 
 
diff --git a/sysdeps/nptl/pthread_mutex_backoff.h b/sysdeps/nptl/pthread_mutex_backoff.h
new file mode 100644
index 0000000000..5b26c22ac7
--- /dev/null
+++ b/sysdeps/nptl/pthread_mutex_backoff.h
@@ -0,0 +1,35 @@
+/* Pthread mutex backoff configuration.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+#ifndef _PTHREAD_MUTEX_BACKOFF_H
+#define _PTHREAD_MUTEX_BACKOFF_H 1
+
+static inline unsigned int
+get_jitter (void)
+{
+  /* Arch dependent random jitter, return 0 disables random.  */
+  return 0;
+}
+
+static inline int
+get_next_backoff (int backoff)
+{
+  /* Next backoff, return 1 disables mutex backoff.  */
+  return 1;
+}
+
+#endif
diff --git a/sysdeps/x86_64/nptl/pthread_mutex_backoff.h b/sysdeps/x86_64/nptl/pthread_mutex_backoff.h
new file mode 100644
index 0000000000..ec74c3d9db
--- /dev/null
+++ b/sysdeps/x86_64/nptl/pthread_mutex_backoff.h
@@ -0,0 +1,39 @@
+/* Pthread mutex backoff configuration.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+#ifndef _PTHREAD_MUTEX_BACKOFF_H
+#define _PTHREAD_MUTEX_BACKOFF_H 1
+
+#include <fast-jitter.h>
+
+static inline unsigned int
+get_jitter (void)
+{
+  return get_fast_jitter ();
+}
+
+#define MAX_BACKOFF 16
+
+static inline int
+get_next_backoff (int backoff)
+{
+  /* Binary expontial backoff. Limiting max backoff
+     can reduce latency in large critical section.  */
+  return (backoff < MAX_BACKOFF) ? backoff << 1 : backoff;
+}
+
+#endif