Category Archives: Investigative Reporting

Windows Timer Resolution: The Great Rule Change

The behavior of the Windows scheduler changed significantly in Windows 10 2004, in a way that will break a few applications, and there appears to have been no announcement, and the documentation has not been updated. This isn’t the first … Continue reading

Posted in Environment, Investigative Reporting, Performance, Rants | Tagged , | 24 Comments

What Outranks Thread Priority?

This investigation started, as so many of mine do, with me minding my own business, not looking for trouble. In this case all I was doing was opening my laptop lid and trying to log on. The first few times … Continue reading

Posted in Investigative Reporting, Performance, uiforetw, xperf | Tagged , , | 8 Comments

O(n^2), again, now in WMI

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 , , , , | 45 Comments

63 Cores Blocked by Seven Instructions

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 , , | 39 Comments

Taskbar Latency and Kernel Calls

I work quickly on my computer and I get frustrated when I am forced to wait on an operation that should be fast. A persistent nuisance on my over-powered home laptop is that closing windows on the taskbar is slow. … Continue reading

Posted in Investigative Reporting, Performance, uiforetw, xperf | Tagged , , , | 41 Comments

O(n^2) in CreateProcess

So many possible introductions to this one: Windows 7: Sheesh, I sure am slow at creating processes Windows 10: Hold my beer… Or how about: A) How long does CreateProcess take on Windows? B) How long would you like it … Continue reading

Posted in Investigative Reporting, Performance, xperf | Tagged | 29 Comments

When Your Profiler Lies

Last week I wrote about the performance consequences of inadvertently loading gdi32.dll into processes that are created and destroyed at very high rates. This week I want to share some techniques for digging deeper into this behavior, and the odd … Continue reading

Posted in Investigative Reporting, Performance, Programming, uiforetw, xperf | Tagged , , | 20 Comments

A Not-Called Function Can Cause a 5X Slowdown

Subtitle: Making Windows Slower Part 3: Process Destruction In the summer of 2017 I wrestled with a Windows performance problem. Process destruction was slow, serialized, and was blocking the system input queue, leading to repeated short mouse-movement hangs when building … Continue reading

Posted in Investigative Reporting, Performance, Programming | Tagged , , | 14 Comments

Making Windows Slower Part 2: Process Creation

Windows has long had a reputation for slow file operations and slow process creation. Have you ever wanted to make these operations even slower? This weeks’ blog post covers a technique you can use to make process creation on Windows … Continue reading

Posted in Code Reliability, Investigative Reporting, Performance, Programming | Tagged , , | 20 Comments

24-core CPU and I can’t type an email (part two)

In my last post I promised to give more details about some rabbit holes that I went down during the investigation, including page tables, locks, WMI, and a vmmap bug. Those details are here, along with updated code samples. But … Continue reading

Posted in Investigative Reporting, memory, Performance | Tagged , , , | 26 Comments