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jboner / latency.txt
Last active May 1, 2026 02:31
Latency Numbers Every Programmer Should Know
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
@jfromaniello
jfromaniello / continous-qunit.ps1
Created August 4, 2011 14:22
The powershell continuously watch for file changes in a directory, then it executes PhantomJs with the Run-Qunit.js attached to your htm qunit test harness.
# watch a file changes in the current directory,
# execute all tests when a file is changed or renamed
$watcher = New-Object System.IO.FileSystemWatcher
$watcher.Path = get-location
$watcher.IncludeSubdirectories = $true
$watcher.EnableRaisingEvents = $false
$watcher.NotifyFilter = [System.IO.NotifyFilters]::LastWrite -bor [System.IO.NotifyFilters]::FileName
while($TRUE){