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/*
* This file is open source software, licensed to you under the terms
* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. 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.
*/
/*
* Copyright (C) 2015 Cloudius Systems, Ltd.
*/
#include <seastar/core/thread.hh>
#include <seastar/core/semaphore.hh>
#include <seastar/core/app-template.hh>
#include <seastar/core/do_with.hh>
#include <seastar/core/distributed.hh>
#include <seastar/core/sleep.hh>
#include <fmt/printf.h>
using namespace seastar;
using namespace std::chrono_literals;
class context_switch_tester {
uint64_t _switches{0};
semaphore _s1{0};
semaphore _s2{0};
bool _done1{false};
bool _done2{false};
thread _t1{[this] { main1(); }};
thread _t2{[this] { main2(); }};
private:
void main1() {
while (!_done1) {
_s1.wait().get();
++_switches;
_s2.signal();
}
_done2 = true;
}
void main2() {
while (!_done2) {
_s2.wait().get();
++_switches;
_s1.signal();
}
}
public:
void begin_measurement() {
_s1.signal();
}
future<uint64_t> measure() {
_done1 = true;
return _t1.join().then([this] {
return _t2.join();
}).then([this] {
return _switches;
});
}
future<> stop() {
return make_ready_future<>();
}
};
int main(int ac, char** av) {
static const auto test_time = 5s;
return app_template().run_deprecated(ac, av, [] {
auto dcstp = std::make_unique<distributed<context_switch_tester>>();
auto& dcst = *dcstp;
return dcst.start().then([&dcst] {
return dcst.invoke_on_all(&context_switch_tester::begin_measurement);
}).then([] {
return sleep(test_time);
}).then([&dcst] {
return dcst.map_reduce0(std::mem_fn(&context_switch_tester::measure), uint64_t(), std::plus<uint64_t>());
}).then([] (uint64_t switches) {
switches /= smp::count;
fmt::print("context switch time: {:5.1f} ns\n",
double(std::chrono::duration_cast<std::chrono::nanoseconds>(test_time).count()) / switches);
}).then([&dcst] {
return dcst.stop();
}).then([dcstp = std::move(dcstp)] {
engine_exit(0);
});
});
}
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