/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <algorithm>
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#include <chrono>
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#include <thread>
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#include <vector>
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#include <sys/capability.h>
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#include <cutils/sched_policy.h>
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#include <gtest/gtest.h>
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bool hasCapSysNice() {
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__user_cap_header_struct header;
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memset(&header, 0, sizeof(header));
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header.version = _LINUX_CAPABILITY_VERSION_3;
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__user_cap_data_struct caps[_LINUX_CAPABILITY_U32S_3];
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if (capget(&header, &caps[0])) {
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GTEST_LOG_(WARNING) << "failed to get process capabilities";
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return false;
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}
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auto nice_idx = CAP_TO_INDEX(CAP_SYS_NICE);
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auto nice_mask = CAP_TO_MASK(CAP_SYS_NICE);
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return caps[nice_idx].effective & nice_mask;
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}
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long long medianSleepTime() {
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std::vector<long long> sleepTimes;
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constexpr size_t numSamples = 100;
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for (size_t i = 0; i < numSamples; i++) {
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auto start = std::chrono::steady_clock::now();
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std::this_thread::sleep_for(std::chrono::nanoseconds(1));
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auto end = std::chrono::steady_clock::now();
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auto diff = end - start;
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sleepTimes.push_back(diff.count());
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}
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constexpr auto median = numSamples / 2;
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std::nth_element(sleepTimes.begin(), sleepTimes.begin() + median,
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sleepTimes.end());
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return sleepTimes[median];
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}
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static void AssertPolicy(SchedPolicy expected_policy) {
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SchedPolicy current_policy;
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ASSERT_EQ(0, get_sched_policy(0, ¤t_policy));
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EXPECT_EQ(expected_policy, current_policy);
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}
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TEST(SchedPolicy, set_sched_policy) {
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if (!schedboost_enabled()) {
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// schedboost_enabled() (i.e. CONFIG_CGROUP_SCHEDTUNE) is optional;
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// it's only needed on devices using energy-aware scheduler.
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GTEST_LOG_(INFO) << "skipping test that requires CONFIG_CGROUP_SCHEDTUNE";
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return;
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}
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ASSERT_EQ(0, set_sched_policy(0, SP_BACKGROUND));
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AssertPolicy(SP_BACKGROUND);
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ASSERT_EQ(0, set_sched_policy(0, SP_FOREGROUND));
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AssertPolicy(SP_FOREGROUND);
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}
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TEST(SchedPolicy, set_sched_policy_timerslack) {
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if (!hasCapSysNice()) {
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GTEST_LOG_(INFO) << "skipping test that requires CAP_SYS_NICE";
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return;
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}
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// A measureable effect of scheduling policy is that the kernel has 800x
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// greater slack time in waking up a sleeping background thread.
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//
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// Look for 10x difference in how long FB and BG threads actually sleep
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// when trying to sleep for 1 ns. This difference is large enough not
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// to happen by chance, but small enough (compared to 800x) to keep inherent
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// fuzziness in scheduler behavior from causing false negatives.
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const unsigned int BG_FG_SLACK_FACTOR = 10;
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ASSERT_EQ(0, set_sched_policy(0, SP_BACKGROUND));
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auto bgSleepTime = medianSleepTime();
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ASSERT_EQ(0, set_sched_policy(0, SP_FOREGROUND));
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auto fgSleepTime = medianSleepTime();
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ASSERT_GT(bgSleepTime, fgSleepTime * BG_FG_SLACK_FACTOR);
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}
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TEST(SchedPolicy, get_sched_policy_name) {
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EXPECT_STREQ("bg", get_sched_policy_name(SP_BACKGROUND));
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EXPECT_STREQ("error", get_sched_policy_name(SchedPolicy(-2)));
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EXPECT_STREQ("error", get_sched_policy_name(SP_CNT));
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}
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