Windows Slowdown, Investigated, Identified, and Now Fixed

A few months I posted about my investigation of a performance problem on my 64-bit Windows laptop. Some mysterious source was doing transient 4 GB allocations which were evicting most data from the file cache. This was making my laptop rely heavily on retrieving data from its hard drive, and that is not a good thing.

My investigation with ETW showed that the problem was a bug in the driver for my imagerecently purchased Western Digital My Book Live backup drive. The driver was telling Windows that the drive’s sector size was 4,294,967,295 bytes (4 GB minus one byte) and Windows was dutifully allocating that big a buffer.


Anyway, the cool thing about blogging is that it can be a great way to report bugs. After writing the original blog post I heard from Microsoft (they might put in a sanity check for the sector size, someday), and I heard from Western Digital. In both cases the contact was through unofficial channels, but I’ll take what I can get. Western Digital acknowledged the bug and promised to fix it.

I just heard back from Western Digital yesterday and apparently a fixed driver is now available. Version was released over the weekend, so if you have this drive be sure to get the update.

It’s always great when the problems that I write about are actually fixed. While three months may not seem particularly agile it is actually really quick for most computer companies.


Unfortunately I can’t test the fix myself as I returned the drive already. If you have this drive and have seen this problem (requires a machine with more than 4 GB of RAM) then let me know if the fix works.

At least I did finally manage to conquer my backup difficulties, with a different external drive.

Additional reading

If you enjoy investigative reporting of performance issues you should take a look at the other articles in the series. If you want to learn how to investigate performance problems using ETW you should check out ETW Central.

About brucedawson

I'm a programmer, working for Google, focusing on optimization and reliability. Nothing's more fun than making code run 10x as fast. Unless it's eliminating large numbers of bugs. I also unicycle. And play (ice) hockey. And sled hockey. And juggle. And worry about whether this blog should have been called randomutf-8. 2010s in review tells more:
This entry was posted in Investigative Reporting, Performance, Programming, xperf and tagged . Bookmark the permalink.

9 Responses to Windows Slowdown, Investigated, Identified, and Now Fixed

  1. Alan says:

    Grats Bruce!

    Thank you for making the world a little bit better of a place. Maybe both parties will realize people are watching and pay a little more attention to these kinds of things in the future 😛

  2. Gareth Pho says:

    I don’t believe this story at all.

  3. I played the video at the bottom of your post, thinking you linked in a video of yourself. However it was some guy making a bet with a pretty girl about texting speeds on a phone. Doh! This is an ad.

    This is the first time I have read your blog. Nice work on detecting your system slowdown and using your blog to see if through to a fix. Maybe future owners of that backup drive with benefit.

    I just read your About page. What kind of games are you working on? Or is this a hush-hush topic?

  4. Pingback: Top Eight Entertaining Blog Facts for 2012 | Random ASCII

  5. Pingback: Windows Slowdown, Investigated and Identified | Random ASCII

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  7. Pingback: ETW Central | Random ASCII

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