Windows handles I/O wait fundamentally different from Linux. While Linux explicitly tracks "iowait" as time when CPUs could have been doing work but were blocked waiting for I/O completion, Windows treats this differently in its performance accounting.

For Windows systems, focus on these Perfmon counters to identify I/O-related CPU contention:

\\Processor(_Total)\% Processor Time
\\Processor(_Total)\% DPC Time
\\Processor(_Total)\% Interrupt Time
\\System\Processor Queue Length
\\PhysicalDisk(*)\Avg. Disk sec/Transfer
\\PhysicalDisk(*)\Current Disk Queue Length

Create a PowerShell script to monitor I/O-bound scenarios:

$counters = @(
    "\Processor(_Total)\% Processor Time",
    "\System\Processor Queue Length",
    "\PhysicalDisk(*)\Avg. Disk sec/Read",
    "\PhysicalDisk(*)\Avg. Disk sec/Write"
)

Get-Counter -Counter $counters -SampleInterval 2 -MaxSamples 5 | 
    ForEach-Object {
        $_.CounterSamples | 
            Format-Table -Property Path, CookedValue -AutoSize
    }

Look for these patterns indicating I/O wait issues:

• High % Processor Time with low Processor Queue Length
• Spikes in DPC or Interrupt Time during disk operations
• Disk latency (Avg. Disk sec/Transfer) > 20ms consistently

When Perfmon isn't sufficient, consider these tools:

# Windows Performance Recorder (WPR)
wpr -start GeneralProfile -start DiskIO -filemode
# ... perform operations ...
wpr -stop output.etl

# ETW tracing for disk I/O
logman create trace "DiskTrace" -o disk.etl -p "Microsoft-Windows-Disk" -ets

For SQL Server workloads, add these specific counters:

\\SQLServer:Buffer Manager\Page life expectancy
\\SQLServer:Access Methods\Full Scans/sec
\\SQLServer:Latches\Latch Waits/sec

Correlate these with disk counters to identify whether CPU waits are computation-bound or I/O-bound.

Unlike Linux which explicitly reports "iowait" as a separate CPU state, Windows handles I/O-bound process accounting differently. In Linux, processes in uninterruptible sleep (D state) are considered as contributing to iowait time, subtracting from idle CPU. Windows Performance Monitor doesn't have an exact equivalent counter, but we can approximate this measurement.

For comprehensive I/O wait analysis in Windows, monitor these key counters:

1. \Processor(_Total)\% Processor Time
2. \Processor(_Total)\% Idle Time
3. \System\Processor Queue Length
4. \PhysicalDisk(*)\% Idle Time
5. \PhysicalDisk(*)\Avg. Disk sec/Transfer
6. \System\Context Switches/sec

While Windows doesn't report iowait directly, you can estimate it using this formula:

Effective I/O Wait = 
    (Measured Idle Time - Expected Idle Time) 
    + (Processor Queue Length * Context Switch Cost)

Here's a PowerShell script to calculate this:

$cpuTime = (Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue
$idleTime = (Get-Counter '\Processor(_Total)\% Idle Time').CounterSamples.CookedValue
$queueLength = (Get-Counter '\System\Processor Queue Length').CounterSamples.CookedValue
$contextSwitches = (Get-Counter '\System\Context Switches/sec').CounterSamples.CookedValue

# Empirical constant for context switch cost (microseconds)
$ctxSwitchCost = 0.5

$effectiveIOWait = ($idleTime - (100 - $cpuTime)) + ($queueLength * $ctxSwitchCost * $contextSwitches / 1000)

Write-Output "Estimated I/O Wait: $effectiveIOWait%"

For more precise measurement, use Event Tracing for Windows (ETW):

logman create trace "IOAnalysis" -ow -o io_trace.etl -p "Windows Kernel Trace" 0x50:0x5 -nb 128 256 -bs 128
logman update trace "IOAnalysis" -p "Microsoft-Windows-Kernel-Processor-Power" 0x1
logman start "IOAnalysis"
# ... run workload ...
logman stop "IOAnalysis"

When analyzing I/O bound performance:

• Disk queue length > 2 per disk typically indicates I/O bottleneck
• Avg. Disk sec/Transfer > 15ms suggests storage latency issues
• High context switches with low CPU utilization often points to I/O wait