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Re: [Xen-devel] atropos scheduler broken

To: xen-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] atropos scheduler broken
From: "Mark A. Williamson" <mark.williamson@xxxxxxxxxxxx>
Date: Tue, 26 Oct 2004 16:45:40 +0000
Cc: Steven Hand <Steven.Hand@xxxxxxxxxxxx>, Diwaker Gupta <diwakergupta@xxxxxxxxx>
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> It is quite possible our current implementation is bugged -- we've
> not gotten around to extensive testing in the recent past.

AFAIK it doesn't behave quite correct.  There's some difficult-to-spot bug 
somewhere in the code - it may well only be a small tweak once tracked down.

This currently looks unlikely to be fixed for 2.0 but hopefully will be fully 
operational in 2.1.

> p.s. you're not running on SMP are you? if so, the domains will be
>      on different CPUs and hence the x flag will cause each of them
>      to get approximately the same allocation, just as you observed.

That's also a good point: Xen effectively runs a uniprocessor scheduler ON 
EACH CPU, with load balancing across CPUs achieved by CPU pinning in domain 
configs or using xm.  If you have one domain on each CPU with the xtratime 
flag set, they'll get all the CPU they want...

HTH,
Mark

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