Date: Fri, 30 Oct 2009 10:30:23 +0100 From: "Mr. Olli" <mister.olli@googlemail.com> To: Carsten Heesch <carsten@ossafe.org> Cc: freebsd-xen@freebsd.org Subject: Re: SCHED_ULE vs SCHED_4BSD for XENHVM domU Message-ID: <1256895023.6479.42.camel@phoenix.blechhirn.net> In-Reply-To: <C83E1FA5-EFF0-49A7-AF53-49F923948DEF@ossafe.org> References: <C83E1FA5-EFF0-49A7-AF53-49F923948DEF@ossafe.org>
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Hi, I compiled FreeBSD8-RC2 from SVN revision 198456 with the XEN config file left unchanged. the domU is 32bit. I'm running on SCHED_ULE and the system consumes <1% vCPU (according to xentop) in idle status. My dom0 is a gentoo linux 32-bit with 2x athlonMP 1900+ and 4GB ram. greetz, ---- Mr. Olli On Thu, 2009-10-29 at 23:12 +0000, Carsten Heesch wrote: > Hi guys, > > After FreeBSD 8.0-RC2 is working well (for me) on Xen 3.3.1, I somehow > made an interesting observation: > > Even if the FreeBSD domU does absolutely nothing, each of the assigned > vCPUs will be reported by xentop as using 15%-25% CPU time. It doesn't > matter, if domU is running with 1 or 4 vCPUs. All of them float at the > same level. > > On the same Xen box five other domU's (CentOS 5.2-5.4) have an idle > CPU percentage of 0 to 0.5%. > > So I played a bit and figured out that changing the scheduler in the > XENHVM kernel configuration from "option SCHED_ULE" to "option > SCHED_4BSD" resolves this problem. The idle state of the FreeBSD domU > is now identical to the CentOS domU's. > > However, this of course means using an old (maybe even deprecated?) > scheduler, which moreover isn't the best choice for multiple > (virtual) CPUs. > > The configuration I tested on is: > Intel i7 920 Quad-Core with Hyperthreading (8 logical CPUs) > Citrix XenServer 5.5 (based on CentOS 5.2, Xen 3.3.1) > > > Any thoughts, ideas, solutions? > > > Thanks! > > Carsten > > > > _______________________________________________ > freebsd-xen@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-xen > To unsubscribe, send any mail to "freebsd-xen-unsubscribe@freebsd.org"
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