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Re: [Xen-devel] Serious performance issues

Ian Pratt wrote:
Are you using the standard bridging scripts? I guess not since your
bridge name is different. The only time I've seen something like this is
when some of the bridge timeout parameters are set to 0 jiffies (setting
to 1 jiffy is OK).

I'm not. I had a fully working UML setup and wanted to share that
between UML and Xen.

The 0 jiffie thing was a good hint. That was the problem with bridge.
I'm guessing I had that issue all along with my native linux setup.


Problem #1: plugging in my Logitech USB trackball creates an uhci_hcd
and timer interrupt storm that degrades performance to about 10% of
normal. Unplug does not stop storm. Unknown cause, not fixed, workaround
is not to plug in any USB device except hubs.

Problem #2: bridge setfd/sethello 0 causes timer interrupt storm, but
does not degrade performance significantly. Workaround is to not set
such low numbers. Will talk to brctl/bridging maintainers to make it
more foolproof.

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