// Licensed to the Apache Software Foundation (ASF) under one // or more contributor license agreements. See the NOTICE file // distributed with this work for additional information // regarding copyright ownership. The ASF licenses this file // to you under the Apache License, Version 2.0 (the // "License"); you may not use this file except in compliance // with the License. You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, // software distributed under the License is distributed on an // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY // KIND, either express or implied. See the License for the // specific language governing permissions and limitations // under the License. // bthread - A M:N threading library to make applications more concurrent. // Author: Ge,Jun (gejun@baidu.com) // Date: Fri Dec 5 13:40:57 CST 2014 #ifndef BTHREAD_PROCESSOR_H #define BTHREAD_PROCESSOR_H #include "butil/build_config.h" // Pause instruction to prevent excess processor bus usage, only works in GCC # ifndef cpu_relax #if defined(ARCH_CPU_ARM_FAMILY) # define cpu_relax() asm volatile("yield\n": : :"memory") #else # define cpu_relax() asm volatile("pause\n": : :"memory") #endif # endif // Compile read-write barrier # ifndef barrier # define barrier() asm volatile("": : :"memory") # endif # define BT_LOOP_WHEN(expr, num_spins) \ do { \ /*sched_yield may change errno*/ \ const int saved_errno = errno; \ for (int cnt = 0, saved_nspin = (num_spins); (expr); ++cnt) { \ if (cnt < saved_nspin) { \ cpu_relax(); \ } else { \ sched_yield(); \ } \ } \ errno = saved_errno; \ } while (0) #endif // BTHREAD_PROCESSOR_H