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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "thread.h"
     18 
     19 #include <errno.h>
     20 #include <limits.h>
     21 #include <sys/resource.h>
     22 #include <sys/time.h>
     23 
     24 #include <cutils/sched_policy.h>
     25 #include <utils/threads.h>
     26 
     27 #include "base/macros.h"
     28 
     29 namespace art {
     30 
     31 // Conversion map for "nice" values.
     32 //
     33 // We use Android thread priority constants to be consistent with the rest
     34 // of the system.  In some cases adjacent entries may overlap.
     35 //
     36 static const int kNiceValues[10] = {
     37   ANDROID_PRIORITY_LOWEST,                // 1 (MIN_PRIORITY)
     38   ANDROID_PRIORITY_BACKGROUND + 6,
     39   ANDROID_PRIORITY_BACKGROUND + 3,
     40   ANDROID_PRIORITY_BACKGROUND,
     41   ANDROID_PRIORITY_NORMAL,                // 5 (NORM_PRIORITY)
     42   ANDROID_PRIORITY_NORMAL - 2,
     43   ANDROID_PRIORITY_NORMAL - 4,
     44   ANDROID_PRIORITY_URGENT_DISPLAY + 3,
     45   ANDROID_PRIORITY_URGENT_DISPLAY + 2,
     46   ANDROID_PRIORITY_URGENT_DISPLAY         // 10 (MAX_PRIORITY)
     47 };
     48 
     49 void Thread::SetNativePriority(int newPriority) {
     50   if (newPriority < 1 || newPriority > 10) {
     51     LOG(WARNING) << "bad priority " << newPriority;
     52     newPriority = 5;
     53   }
     54 
     55   int newNice = kNiceValues[newPriority-1];
     56   pid_t tid = GetTid();
     57 
     58   // TODO: b/18249098 The code below is broken. It uses getpriority() as a proxy for whether a
     59   // thread is already in the SP_FOREGROUND cgroup. This is not necessarily true for background
     60   // processes, where all threads are in the SP_BACKGROUND cgroup. This means that callers will
     61   // have to call setPriority twice to do what they want :
     62   //
     63   //     Thread.setPriority(Thread.MIN_PRIORITY);  // no-op wrt to cgroups
     64   //     Thread.setPriority(Thread.MAX_PRIORITY);  // will actually change cgroups.
     65   if (newNice >= ANDROID_PRIORITY_BACKGROUND) {
     66     set_sched_policy(tid, SP_BACKGROUND);
     67   } else if (getpriority(PRIO_PROCESS, tid) >= ANDROID_PRIORITY_BACKGROUND) {
     68     set_sched_policy(tid, SP_FOREGROUND);
     69   }
     70 
     71   if (setpriority(PRIO_PROCESS, tid, newNice) != 0) {
     72     PLOG(INFO) << *this << " setPriority(PRIO_PROCESS, " << tid << ", " << newNice << ") failed";
     73   }
     74 }
     75 
     76 int Thread::GetNativePriority() {
     77   errno = 0;
     78   int native_priority = getpriority(PRIO_PROCESS, 0);
     79   if (native_priority == -1 && errno != 0) {
     80     PLOG(WARNING) << "getpriority failed";
     81     return kNormThreadPriority;
     82   }
     83 
     84   int managed_priority = kMinThreadPriority;
     85   for (size_t i = 0; i < arraysize(kNiceValues); i++) {
     86     if (native_priority >= kNiceValues[i]) {
     87       break;
     88     }
     89     managed_priority++;
     90   }
     91   if (managed_priority > kMaxThreadPriority) {
     92     managed_priority = kMaxThreadPriority;
     93   }
     94   return managed_priority;
     95 }
     96 
     97 void Thread::SetUpAlternateSignalStack() {
     98   // Bionic does this for us.
     99 }
    100 
    101 void Thread::TearDownAlternateSignalStack() {
    102   // Bionic does this for us.
    103 }
    104 
    105 }  // namespace art
    106