Tag Archives: ETW

O(n^2), again, now in WMI

Posted on December 8, 2019 by

I recently hit some multi-minute delays on my workstation. After investigating I found that the problem was due to a lock being held for five minutes, and during that time the lock-holder was mostly just spinning in a nine-instruction loop. … Continue reading →

Posted in Investigative Reporting, Programming, Rants, uiforetw, xperf | Tagged , , , , | 43 Comments

63 Cores Blocked by Seven Instructions

Posted on October 20, 2019 by

I seem to have a habit of writing about super powerful machines whose many cores are laid low by misuse of locks. So. Yeah. It’s that again. But this one seems particularly impressive. I mean, how often do you have … Continue reading →

Posted in Investigative Reporting, Performance, Programming, uiforetw, xperf | Tagged , , | 37 Comments

Compiler bug? Linker bug? Windows Kernel bug.

Posted on February 25, 2018 by

See the end of the post for an October 2018 bug fix update, or read the whole story: Flaky failures are the worst. In this particular investigation, which spanned twenty months, we suspected hardware failure, compiler bugs, linker bugs, and … Continue reading →

Posted in Debugging, Investigative Reporting, Programming | Tagged , , , | 65 Comments

CPU Performance Counters on Windows

Posted on November 27, 2016 by

TL;DR – I can finally record CPU performance counters for processes on Windows. I’m mostly a Windows developer but I’ll occasionally fire up my Linux box to use the perf tool to examine CPU performance counters. Sometimes you really need … Continue reading →

Posted in xperf | Tagged , , | 10 Comments

WPA Symbol Loading is Much Faster, but Broken for Chrome

Posted on November 7, 2016 by

There’s good news, and there’s bad news. The good news is that the latest Windows Performance Analyzer (WPA), the visualization tool for ETW (Event Tracing for Windows) traces, can now load symbols faster than ever before – it’s multi-threaded, and … Continue reading →

Posted in uiforetw | Tagged , , , | 4 Comments

ETW Central

Posted on September 24, 2015 by

Over the last few years I’ve written over forty blog posts that discuss ETW/xperf profiling. I’ve done this because it’s one of the best profilers I’ve ever used, and it’s been woefully undersold and under documented by Microsoft. My goal … Continue reading →

Posted in uiforetw, xperf | Tagged , , , , | 59 Comments

Xperf Basics: Recording a Trace (the ultimate easy way)

Posted on September 1, 2015 by

This post can be found through https://tinyurl.com/etwtracing, and an alternate version of these instructions can be found here. If your Windows computer is running slowly – if a program takes a long time to launch, if a game has a … Continue reading →

Posted in Performance, Programming, uiforetw, xperf | Tagged , , | 50 Comments