| // 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. |
| |
| #ifndef __LINUX_SCHED_HPP__ |
| #define __LINUX_SCHED_HPP__ |
| |
| // This file contains Linux-only OS utilities. |
| #ifndef __linux__ |
| #error "linux/sched.hpp is only available on Linux systems." |
| #endif |
| |
| #include <sched.h> |
| // Some old distributions, e.g., Redhat 5.5, do not correctly include |
| // linux/sched.h. |
| #include <linux/sched.h> |
| |
| |
| #include <sys/types.h> |
| |
| #include <stout/error.hpp> |
| #include <stout/none.hpp> |
| #include <stout/nothing.hpp> |
| #include <stout/option.hpp> |
| #include <stout/try.hpp> |
| |
| namespace sched { |
| |
| enum Policy |
| { |
| OTHER = SCHED_OTHER, // Default policy. |
| BATCH = SCHED_BATCH, // Non-interactive, CPU intensive. |
| IDLE = SCHED_IDLE, // Very low priority. |
| FIFO = SCHED_FIFO, // Realtime. |
| RR = SCHED_RR // Realtime, round-robin. |
| }; |
| |
| |
| namespace policy { |
| |
| // Return the current scheduling policy for the specified pid, or for |
| // the caller if pid is None() or zero. |
| inline Try<Policy> get(const Option<pid_t>& pid = None()) |
| { |
| int status = sched_getscheduler(pid.isSome() ? pid.get() : 0); |
| |
| if (status == -1) { |
| return ErrnoError("Failed to get scheduler policy"); |
| } |
| |
| return static_cast<Policy>(status); |
| } |
| |
| |
| // Set the scheduling policy for the specified pid, or for the caller |
| // if pid is None() or zero. Only realtime scheduling policies (FIFO |
| // and RR) accept a priority (within a range, see |
| // sched_setscheduler(2)). |
| // TODO(idownes): Add wrappers around sched_get_priority_{min,max}. |
| inline Try<Nothing> set( |
| Policy policy, |
| const Option<pid_t>& pid = None(), |
| int priority = 0) |
| { |
| if ((policy == OTHER || policy == BATCH || policy == IDLE) && |
| priority != 0) { |
| return Error("Non-real-time scheduling policies only support priority = 0"); |
| } |
| |
| sched_param param; |
| param.sched_priority = priority; |
| |
| if (sched_setscheduler(pid.isSome() ? pid.get() : 0, policy, ¶m) == -1) { |
| return ErrnoError("Failed to set scheduler policy"); |
| } |
| |
| return Nothing(); |
| } |
| |
| } // namespace policy { |
| } // namespace sched { |
| |
| #endif // __LINUX_SCHED_HPP__ |