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henrikandhenrikand
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Update IdleWakeups.cs
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‎TraceProcessors/IdleWakeups/IdleWakeups.cs

Lines changed: 184 additions & 45 deletions
Original file line numberDiff line numberDiff line change
@@ -24,68 +24,207 @@ limitations under the License.
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// Note that this URL has changed once already, so caveat blog lector
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using Microsoft.Windows.EventTracing;
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class IdleWakeups
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using Microsoft.Windows.EventTracing.Symbols;
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namespace IdleWakeups
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{
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static void ProcessTrace(ITraceProcessor trace)
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// A summary of a particular idle wakeup call stack including its count and all frames in the
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// stack.
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struct StackDetails
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{
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public long Count;
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public IReadOnlyList<StackFrame> Stack;
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}
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class SnapshotSummary
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{
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// Specify what data we want, process the trace, then get the data.
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var pendingContextSwitchData = trace.UseContextSwitchData();
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trace.Process();
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var csData = pendingContextSwitchData.Result;
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long chromeSwitches = 0;
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long chromeIdleSwitches = 0;
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// Iterate through all context switches in the trace.
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foreach (var contextSwitch in csData.ContextSwitches)
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public SnapshotSummary(Dictionary<string, StackDetails> idleWakeupsByStackId)
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{
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var imageName = contextSwitch.SwitchIn.Process.ImageName;
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var oldImageName = contextSwitch.SwitchOut.Process.ImageName;
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// Gets the stack of the thread switching in.
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var callStack = contextSwitch.SwitchIn.Stack;
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if (imageName == "chrome.exe")
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idleWakeupsByStackId_ = idleWakeupsByStackId;
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}
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public Dictionary<string, StackDetails> idleWakeupsByStackId_;
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public Dictionary<Int32, long> previousCStates_ = null;
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public long chromeSwitches_ = 0;
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public long chromeIdleSwitches_ = 0;
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}
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class IdleWakeupsAnalysis
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{
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// Process a trace and create a summary.
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private static SnapshotSummary GetIdleWakeupsSummary(ITraceProcessor trace)
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{
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var pendingCpuSchedulingData = trace.UseCpuSchedulingData();
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var pendingSymbols = trace.UseSymbols();
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trace.Process();
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var cpuSchedData = pendingCpuSchedulingData.Result;
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var symbols = pendingSymbols.Result;
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symbols.LoadSymbolsForConsoleAsync(SymCachePath.Automatic).GetAwaiter().GetResult();
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// Key: string which identifies a callstack.
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// Value: counts the frequency of a given key and also stores a list of all stack
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// frames for the callstack.
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var idleWakeupsStack = new Dictionary<string, StackDetails>();
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long chromeSwitches = 0;
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long chromeIdleSwitches = 0;
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var previousCStates = new Dictionary<Int32, long>();
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// Scan all context switches and build up the dictionary based on all detected idle
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// wakeups where chrome.exe wakes up the Idle thread.
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foreach (var contextSwitch in cpuSchedData.ContextSwitches)
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{
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chromeSwitches++;
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if (oldImageName == "Idle")
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var switchInImageName = contextSwitch.SwitchIn.Process.ImageName;
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var switchOutImageName = contextSwitch.SwitchOut.Process.ImageName;
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var callStackIn = contextSwitch.SwitchIn.Stack;
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if (switchInImageName == "chrome.exe")
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{
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chromeIdleSwitches++;
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if (callStack != null)
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chromeSwitches++;
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if (switchOutImageName == "Idle")
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{
53-
Console.WriteLine("IThreadStack.IsIdle: {0}", callStack.IsIdle);
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// Idle wakeup is detected.
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chromeIdleSwitches++;
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var prevCState = contextSwitch.PreviousCState;
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if (prevCState.HasValue)
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{
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previousCStates.TryGetValue(prevCState.Value, out long count);
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count += 1;
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previousCStates[prevCState.Value] = count;
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}
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if (callStackIn == null)
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{
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continue;
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}
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try
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{
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// Get a string that allows us to identify the callstack and use it as
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// key in a dictionary which stores count and the complete stack as
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// value.
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var analyzerStringId = callStackIn.GetAnalyzerString();
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// List of frames in the stack.
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var stackFrames = callStackIn.Frames;
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// Update the dictionary.
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idleWakeupsStack.TryGetValue(analyzerStringId, out StackDetails value);
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value.Count += 1;
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value.Stack = callStackIn.Frames;
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idleWakeupsStack[analyzerStringId] = value;
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}
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catch (Exception ex)
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{
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Console.WriteLine(ex.ToString());
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}
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}
55120
}
56121
}
57-
}
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Console.WriteLine("{0} idlewakeups out of {1} context switches ({2:P}).",
59-
chromeIdleSwitches, chromeSwitches,
60-
chromeIdleSwitches / (double)chromeSwitches);
61-
}
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63-
static void Main(string[] args)
64-
{
65-
foreach (string traceName in args)
123+
var result = new SnapshotSummary(idleWakeupsStack);
124+
result.previousCStates_ = previousCStates;
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result.chromeIdleSwitches_ = chromeIdleSwitches;
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result.chromeSwitches_ = chromeSwitches;
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return result;
129+
}
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static void Main(string[] args)
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{
67-
Console.WriteLine("Processing trace '{0}'", traceName);
68-
var settings = new TraceProcessorSettings
132+
string traceName = "";
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bool showSummary = false;
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foreach (string arg in args)
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{
70-
// Don't print a setup message on first run.
71-
SuppressFirstTimeSetupMessage = true
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};
73-
try
136+
if (arg == "-s" || arg == "--summary")
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showSummary = true;
138+
else if (traceName.Length == 0)
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traceName = arg;
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else
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{
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Console.Error.WriteLine("error: unrecognized arguments: {0}", arg);
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return;
144+
}
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}
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147+
if (traceName.Length == 0)
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{
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Console.Error.WriteLine("usage: IdleWakeups.exe [-s,--summary] <filename>");
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Console.Error.WriteLine("error: too few arguments");
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return;
152+
}
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154+
if (!File.Exists(traceName))
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{
75-
using (ITraceProcessor trace = TraceProcessor.Create(traceName, settings))
76-
ProcessTrace(trace);
156+
Console.Error.WriteLine("File '{0}' does not exist.", traceName);
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return;
77158
}
78-
catch (TraceLostEventsException e)
159+
using (ITraceProcessor trace = TraceProcessor.Create(traceName))
79160
{
80-
Console.WriteLine(e.Message);
81-
Console.WriteLine("Trying again with AllowLostEvents specified. Results may be less reliable.");
82-
Console.WriteLine();
161+
Console.WriteLine("Processing trace '{0}'", Path.GetFileName(traceName));
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163+
// Scan all context switches and store callstacks where Chrome causes an idle
164+
// wakeup. Also store the frequency of each unique callstack.
165+
var iwakeups = GetIdleWakeupsSummary(trace);
166+
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// Print out a summary of all callstacks that causes idle wakeups.
168+
// Example (can be later be used as input to separate Go-script which converts the
169+
// list into something that can be read by pprof):
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//
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// iwakeup:
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// ntoskrnl.exe!SwapContext
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// ntoskrnl.exe!KiSwapContext
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// ...
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// ntdll.dll!RtlUserThreadStart
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// 1070
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// iwakeup:
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// ntoskrnl.exe!SwapContext
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// ntoskrnl.exe!KiSwapContext
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// ..
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// ntdll.dll!RtlUserThreadStart
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// 1011
183+
const int maxPrinted = 40;
184+
var sortedStackEntries =
185+
new List<KeyValuePair<string, StackDetails>>(iwakeups.idleWakeupsByStackId_);
186+
sortedStackEntries.Sort((x, y) => y.Value.Count.CompareTo(x.Value.Count));
187+
foreach (KeyValuePair<string, StackDetails> kvp in sortedStackEntries.Take(maxPrinted))
188+
{
189+
Console.WriteLine("iwakeup:");
190+
foreach (var entry in kvp.Value.Stack)
191+
{
192+
try
193+
{
194+
var stackFrame = entry.GetAnalyzerString();
195+
Console.WriteLine(" {0}", stackFrame);
196+
}
197+
catch (Exception ex)
198+
{
199+
// Console.WriteLine(ex.ToString());
200+
}
201+
}
202+
Console.WriteLine(" {0}", kvp.Value.Count);
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}
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// Only append a summary if it was explicitly specified using the '-s' argument.
206+
if (!showSummary)
207+
{
208+
return;
209+
}
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211+
// Append a short summary of the relationship between the total amount of detected
212+
// context switches caused by Chrome and those that caused an idle wakeup.
213+
Console.WriteLine("{0} idlewakeups out of {1} context switches ({2:P}).",
214+
iwakeups.chromeIdleSwitches_, iwakeups.chromeSwitches_,
215+
iwakeups.chromeIdleSwitches_ / (double)iwakeups.chromeSwitches_);
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84-
settings.AllowLostEvents = true;
85-
using (ITraceProcessor trace = TraceProcessor.Create(traceName, settings))
86-
ProcessTrace(trace);
217+
// Append summary of C-state residencies (@ Idle -> chrome.exe).
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var list = iwakeups.previousCStates_.Keys.ToList();
219+
list.Sort();
220+
Console.WriteLine("Previous C-State (Idle -> chrome.exe):");
221+
foreach (var key in list)
222+
{
223+
Console.WriteLine(" C{0}: {1,7} ({2,6:P})",
224+
key, iwakeups.previousCStates_[key],
225+
iwakeups.previousCStates_[key] / (double)iwakeups.chromeIdleSwitches_);
226+
}
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}
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}
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}
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}
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