Re: [PATCH 4/6] RTC: Ratelimit "lost interrupts" message

From: Roland Dreier
Date: Thu May 24 2007 - 17:15:29 EST


> > I got it a lot when using any sort of virtualization on my Core2Duo
> > (kvm, vmware, qemu). Just a big spew. Honestly, I was getting this with
> > 2.6.20, and haven't tested again with latest kernel.
>
> OK, a bit of googling finds things like this:
> http://chxo.com/be2/20060821_3333.html, so I assume that it's some sort of
> generic problem with the hypervisor's emulation of the RTC.

Actually I saw this "lost interrupts" spew on the host (ie the
non-virtualized kernel) running just plain qemu (no kvm or anything
scary like that). It seemed to be some long irqs-off latency in the
tun/tap or bridging code (it went away when I stopped using "-net tap"
on the qemu command line), but I never succeeded in getting Ingo's
latency tracer to be able to track it down.

- R.
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