test_total_cpu_time.js

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"use strict";

var cpuThreadCount;

add_task(async function setup() {

  // FOG needs a profile directory to put its data in.

  do_get_profile();

  Services.fog.initializeFOG();

  cpuThreadCount = (await Services.sysinfo.processInfo).count;

});

async function getCpuTimeFromProcInfo() {

  const NS_PER_MS = 1000000;

  let cpuTimeForProcess = p => p.cpuTime / NS_PER_MS;

  let procInfo = await ChromeUtils.requestProcInfo();

  return (

    cpuTimeForProcess(procInfo) +

    procInfo.children.map(cpuTimeForProcess).reduce((a, b) => a + b, 0)

);

add_task(async function test_totalCpuTime_in_parent() {

  let startTime = Date.now();

  let initialProcInfoCpuTime = Math.floor(await getCpuTimeFromProcInfo());

  await Services.fog.testFlushAllChildren();

  let initialCpuTime = Glean.power.totalCpuTimeMs.testGetValue();

  Assert.greater(

    initialCpuTime,

0,

    "The CPU time used by starting the test harness should be more than 0"

);

  let initialProcInfoCpuTime2 = Math.ceil(await getCpuTimeFromProcInfo());

  Assert.greaterOrEqual(

    initialCpuTime,

    initialProcInfoCpuTime,

    "The CPU time reported through Glean should be at least as much as the CPU time reported by ProcInfo before asking Glean for the data"

);

  Assert.lessOrEqual(

    initialCpuTime,

    initialProcInfoCpuTime2,

    "The CPU time reported through Glean should be no more than the CPU time reported by ProcInfo after asking Glean for the data"

);

  // 50 is an arbitrary value, but the resolution is 16ms on Windows,

  // so this needs to be significantly more than 16.

  const kBusyWaitForMs = 50;

  while (Date.now() - startTime < kBusyWaitForMs) {

    // Burn CPU time...

  let additionalProcInfoCpuTime =

    Math.floor(await getCpuTimeFromProcInfo()) - initialProcInfoCpuTime2;

  await Services.fog.testFlushAllChildren();

  let additionalCpuTime =

    Glean.power.totalCpuTimeMs.testGetValue() - initialCpuTime;

  info(

    `additional CPU time according to ProcInfo: ${additionalProcInfoCpuTime}ms and Glean ${additionalCpuTime}ms`

);

  // On a machine where the CPU is very busy, our busy wait loop might burn less

  // CPU than expected if other processes are being scheduled instead of us.

  let expectedAdditionalCpuTime = Math.min(

    additionalProcInfoCpuTime,

    kBusyWaitForMs

);

  Assert.greaterOrEqual(

    additionalCpuTime,

    expectedAdditionalCpuTime,

    `The total CPU time should have increased by at least ${expectedAdditionalCpuTime}ms`

);

  let wallClockTime = Date.now() - startTime;

  Assert.lessOrEqual(

    additionalCpuTime,

    wallClockTime * cpuThreadCount,

    `The total CPU time should have increased by at most the wall clock time (${wallClockTime}ms) * ${cpuThreadCount} CPU threads`

);

});

add_task(async function test_totalCpuTime_in_child() {

  const MESSAGE_CHILD_TEST_DONE = "ChildTest:Done";

  let startTime = Date.now();

  await Services.fog.testFlushAllChildren();

  let initialCpuTime = Glean.power.totalCpuTimeMs.testGetValue();

  let initialProcInfoCpuTime = await getCpuTimeFromProcInfo();

  run_test_in_child("test_total_cpu_time_child.js");

  let burntCpuTime = await do_await_remote_message(MESSAGE_CHILD_TEST_DONE);

  let additionalProcInfoCpuTime =

    (await getCpuTimeFromProcInfo()) - initialProcInfoCpuTime;

  await Services.fog.testFlushAllChildren();

  let additionalCpuTime =

    Glean.power.totalCpuTimeMs.testGetValue() - initialCpuTime;

  info(

    `additional CPU time according to ProcInfo: ${additionalProcInfoCpuTime}ms and Glean ${additionalCpuTime}ms`

);

  // On a machine where the CPU is very busy, our busy wait loop might burn less

  // CPU than expected if other processes are being scheduled instead of us.

  let expectedAdditionalCpuTime = Math.min(

    Math.floor(additionalProcInfoCpuTime),

    burntCpuTime

);

  Assert.greaterOrEqual(

    additionalCpuTime,

    expectedAdditionalCpuTime,

    `The total CPU time should have increased by at least ${expectedAdditionalCpuTime}ms`

);

  let wallClockTime = Date.now() - startTime;

  Assert.lessOrEqual(

    additionalCpuTime,

    wallClockTime * cpuThreadCount,

    `The total CPU time should have increased by at most the wall clock time (${wallClockTime}ms) * ${cpuThreadCount} CPU threads`

);

});