1 files changed, 79 insertions, 0 deletions
diff --git a/src/mongo/platform/pause.h b/src/mongo/platform/pause.h
new file mode 100644
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+++ b/src/mongo/platform/pause.h
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+/**
+ * Copyright (C) 2016 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+#pragma once
+
+/**
+ * MONGO_YIELD_CORE_FOR_SMT
+ * - An architecture specific processor hint to allow the processor to yield. It is designed to
+ *   improve the performance of spin-wait loops.
+ *
+ * See src/third_party/wiredtiger/src/include/gcc.h
+ */
+#ifndef __MSC_VER
+
+#if defined(x86_64) || defined(__x86_64__)
+
+#include <xmmintrin.h>
+
+/* Pause instruction to prevent excess processor bus usage */
+#define MONGO_YIELD_CORE_FOR_SMT() _mm_pause()
+
+#elif defined(i386) || defined(__i386__)
+
+#include <xmmintrin.h>
+
+#define MONGO_YIELD_CORE_FOR_SMT() _mm_pause()
+
+#elif defined(__PPC64__) || defined(PPC64)
+
+/* ori 0,0,0 is the PPC64 noop instruction */
+#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("ori 0,0,0" ::: "memory")
+
+#elif defined(__aarch64__)
+
+#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("yield" ::: "memory")
+
+#elif defined(__s390x__)
+
+#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("lr 0,0" ::: "memory")
+
+#elif defined(__sparc__)
+
+#define MONGO_YIELD_CORE_FOR_SMT() __asm__ volatile("rd %%ccr, %%g0" ::: "memory")
+
+#else
+#error "No processor pause implementation for this architecture."
+#endif
+
+#else
+
+// On Windows, use the winnt.h YieldProcessor macro
+#define MONGO_YIELD_CORE_FOR_SMT() YieldProcessor()
+
+#endif