Date: Thu, 29 Oct 2009 23:33:23 +0000 From: Carsten Heesch <sysconfig@ossafe.org> To: Carsten Heesch <sysconfig@ossafe.org> Cc: freebsd-xen@freebsd.org Subject: Re: SCHED_ULE vs SCHED_4BSD for XENHVM domU Message-ID: <E7CC1E39-5AD3-47A4-B48C-F4176D486FB4@ossafe.org> In-Reply-To: <869459F8-7490-4270-84D0-A1168002E509@ossafe.org> References: <869459F8-7490-4270-84D0-A1168002E509@ossafe.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Oops, sorry for posting this twice. I thought it didn't go through with the first attempt. On 29 Oct 2009, at 23:27, 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" Best regards, Carsten Heesch Mobile: +44 (0)7889-129998 Mail: carsten@heesch.me.uk Skype: carstenh74
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?E7CC1E39-5AD3-47A4-B48C-F4176D486FB4>