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Jesse
Asked: 2012-04-13 10:02:21 +0800 CST

IIS 7 -- how to track down mysterious network & cpu usage?

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I've got a 64-bit Server 2008 (R1) box running IIS. Users were complaining about extremely slow-loading pages. After digging around I found:

  1. After isolating the box so only one user was able to connect, each web request caused the CPU to jump to 30% for about two seconds, even on the simplest of pages. Looking at the code, no obvious reason for this usage is apparent.

  2. NewRelic shows > 10s lost to "networking", even though all the access is over a 100-meg LAN, and perfmon shows a network Output Queue Length of zero.

We can't find anything in the code that should cause so much CPU activity, or any answer to why NewRelic thinks there's a network problem.

Looking for suggestions of where to go from here.

iis-7 performance-tuning

2 Answers

  1. Windows Server 2008 enabled a new network feature by default Scalable Networking Pak. I think this feature causes more issues than it solves. Here is 2 articles refer to this issue:
    TCP Chimney
    Microsoft Support article: KB951037

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  2. You might also find Failed Request Tracing useful here. The name is a little too specific actually, cause the feature enables tracing any type of request.

    Tess Ferrandez over at MSDN wrote a brilliant article about performance troubleshooting with Failed Request Tracing, definitely worth a read in this type of scenario

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