e09bd6ea71
The A/B harness used to measure the idle-sleep work that shipped in main (#2559): Measure-EventLoop.ps1 and measure-event-loop.sh drive CPU/lag comparisons across server.eventLoopIdleWaitMs settings, and HostLatencyProbe.cs measures what basic operations cost on a host. dev-docs/measuring-event-loop.md explains the method, the numbers that matter, and how to re-vendor IORingGroup for ring experiments. This branch is main plus this commit, rebased forward as main moves. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
96 lines
3.4 KiB
PowerShell
96 lines
3.4 KiB
PowerShell
# A/B measurement for the event loop scheduler.
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#
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# Boots the shard twice against identical binaries -- once with idle sleeping disabled
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# (server.eventLoopIdleWaitMs = 0) and once with idle sleeping (= 2) -- and samples process CPU
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# time over a fixed window. Everything else is held constant, so the delta is the scheduler.
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#
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# Usage: pwsh tools/Measure-EventLoop.ps1 [-WarmupSeconds 45] [-SampleSeconds 60]
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param(
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[int]$WarmupSeconds = 45,
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[int]$SampleSeconds = 60
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)
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$ErrorActionPreference = 'Stop'
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$root = Split-Path -Parent $PSScriptRoot
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$dist = Join-Path $root 'Distribution'
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$exe = Join-Path $dist 'ModernUO.exe'
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$configPath = Join-Path $dist 'Configuration\modernuo.json'
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if (-not (Test-Path $exe)) {
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throw "ModernUO.exe not found at $exe. Build with: dotnet build -c Release"
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}
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function Set-IdleWait([int]$value) {
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$json = Get-Content $configPath -Raw | ConvertFrom-Json
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$json.settings.'server.eventLoopIdleWaitMs' = "$value"
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$json | ConvertTo-Json -Depth 20 | Set-Content $configPath -Encoding UTF8
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}
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function Measure-Loop([int]$idleWait, [string]$label) {
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Set-IdleWait $idleWait
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Write-Host ""
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Write-Host "=== $label (server.eventLoopIdleWaitMs = $idleWait) ===" -ForegroundColor Cyan
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# Redirect stdin from an empty file so the server runs headless and never blocks on console
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# input. PowerShell cannot redirect from NUL, so an actual empty file stands in for it.
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$stdin = Join-Path $dist 'empty.in'
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if (-not (Test-Path $stdin)) {
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Set-Content -Path $stdin -Value '' -NoNewline
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}
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$proc = Start-Process -FilePath $exe -WorkingDirectory $dist -PassThru `
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-RedirectStandardInput $stdin `
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-RedirectStandardOutput (Join-Path $dist "Logs\measure-$idleWait.out") `
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-RedirectStandardError (Join-Path $dist "Logs\measure-$idleWait.err")
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try {
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Write-Host " pid $($proc.Id); warming up for ${WarmupSeconds}s..."
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Start-Sleep -Seconds $WarmupSeconds
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if ($proc.HasExited) {
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throw "Server exited during warmup (code $($proc.ExitCode)). See Logs\measure-$idleWait.err"
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}
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$proc.Refresh()
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$cpuBefore = $proc.TotalProcessorTime
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$wallBefore = Get-Date
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Write-Host " sampling for ${SampleSeconds}s..."
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Start-Sleep -Seconds $SampleSeconds
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$proc.Refresh()
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$cpuAfter = $proc.TotalProcessorTime
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$wallAfter = Get-Date
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$cpuMs = ($cpuAfter - $cpuBefore).TotalMilliseconds
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$wallMs = ($wallAfter - $wallBefore).TotalMilliseconds
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$pct = $cpuMs / $wallMs * 100
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Write-Host (" CPU: {0:F2}% of one core ({1:F0}ms CPU over {2:F0}ms wall)" -f $pct, $cpuMs, $wallMs) -ForegroundColor Yellow
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[pscustomobject]@{ Label = $label; IdleWait = $idleWait; CpuPercent = $pct }
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}
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finally {
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if (-not $proc.HasExited) {
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$proc.Kill()
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$proc.WaitForExit(10000) | Out-Null
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}
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}
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}
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$legacy = Measure-Loop 0 'Never sleep (max responsiveness)'
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$sleeping = Measure-Loop 2 'Idle sleeping'
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Write-Host ""
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Write-Host "=== Result ===" -ForegroundColor Green
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Write-Host (" never sleep : {0,6:F2}% of one core" -f $legacy.CpuPercent)
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Write-Host (" idle sleep : {0,6:F2}% of one core" -f $sleeping.CpuPercent)
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if ($sleeping.CpuPercent -gt 0) {
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Write-Host (" reduction : {0,6:F1}x" -f ($legacy.CpuPercent / $sleeping.CpuPercent))
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}
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# Leave the config on the new behaviour.
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Set-IdleWait 2
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