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Re: [Qemu-devel] kernel 2.6 losing too many ticks

From: Juergen Lock
Subject: Re: [Qemu-devel] kernel 2.6 losing too many ticks
Date: Sat, 2 Oct 2004 01:32:39 +0200

On Fri, Oct 01, 2004 at 07:43:20PM +0000, bennet wrote:
> A speedup can  be made by passing clock=pit to the kernel parameters (at 
> lilo  prompt: linux clock=pit)
> But there's still a problem with some timers : sleep 1 sleeps for about 
> 10 seconds !
> I can't find why, and don't know how to get more information to solve 
> the problem.

This happens when the host's hz is < than the guest's: linux 2.4 kernels
have a default of 100 and 2.6 kernels of 1000 -> factor 10, which you see
with `sleep 1'.  Also, qemu has an internal limit of 1000 (or 1024?),
so if your guest's hz is > than that it'll still be slow even if the
hosts's hz is as fast or faster.  (Maybe this should be made configurable?
some ppl use e.g. hz 5000 to increase gig ethernet performance, like
the FreeSBIE kernel...)


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