Date: Sun, 8 Oct 2006 15:51:50 -0700 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: David Xu <davidxu@freebsd.org> Cc: freebsd-current@freebsd.org, Kip Macy <kmacy@fsmware.com>, Ivan Voras <ivoras@fer.hr> Subject: Re: [PATCH] MAXCPU alterable in kernel config - needs testers Message-ID: <20061008225150.GK793@funkthat.com> In-Reply-To: <200610090634.31297.davidxu@freebsd.org> References: <2fd864e0610080423q7ba6bdeal656a223e662a5d@mail.gmail.com> <20061008135031.G83537@demos.bsdclusters.com> <4529667D.8070108@fer.hr> <200610090634.31297.davidxu@freebsd.org>
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David Xu wrote this message on Mon, Oct 09, 2006 at 06:34 +0800:
> On Monday 09 October 2006 04:58, Ivan Voras wrote:
> > Kip Macy wrote:
> > > It will only cover the single chip Niagara 2 boxes.
> >
> > Oh right, they'll doing multi chips in Niagara 2 :) Go Sun :)
> >
> > Still, single T2 chips should be more common, so I'd guess it will pay
> > to optimize for that case.
> >
> > (For the rest of the audience: Niagara 1 has 32 logical CPUs and
> > supports only one physical CPU/socket; Niagara 2 will have 64 logical
> > CPUs and support > 1 CPUs/sockets; so a 2 socket Niagara 2 box will have
> > 128 logical processors! Cue SciFi music...)
> >
> > Any word on how will they handle migration of threads across sockets (or
> > will it be OS's job)? Judging from T1 architecture, I think such event
> > would create a very large performance penalty, but I'm not an expert.
> > __________
>
> The current 4BSD scheduler does not handle large number of cores very well,
> also the single sched_lock will be a bottleneck for such a configuration.
Bad enough that Kip had to reduce HZ down to 100... since sched_lock
ends up serializing ALL cpus when scheduling needs to happen..
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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