Date: Tue, 18 Mar 2008 19:45:53 +1100 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Chuck Robey <chuckr@chuckr.org> Cc: FreeBSD-arch@freebsd.org Subject: Re: difference between this and that Message-ID: <20080318084553.GD44676@server.vk2pj.dyndns.org> In-Reply-To: <47DF1257.9080807@chuckr.org> References: <47DF1257.9080807@chuckr.org>
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--xs+9IvWevLaxKUtW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Mar 17, 2008 at 08:52:39PM -0400, Chuck Robey wrote: >I was giving some thought recently, to the trend towards adding more and >more cores to a single chip, and wondering if maybe, in the next years >ahead, if we wouldn't be seeing things that sound loony today, like a 4096 >core motherboard. Actually, there was a bit of a side-thread about this sort of thing on the CVS mailing lists a couple of weeks ago. Definitely lots of cores per system are on the way. You can buy a system with 64 hardware threads from Sun today. A 128-thread system (dual T-2) will arrive RSN and Sun have said they intend to double the threads-per-chip every year. 4096 cores is still a way off and it's not currently clear what will drive these sort of systems into the mainstream. One problem is that FreeBSD currently assumes that a CPU mask will fit into a long - this limits FreeBSD to 32 cores on arm/i386/ppc and 64 cores elsewhere. Getting rid of this limit is going to take some work. >With this in mind, could I ask for a little bit of discussion on the >differences between the SMP management that FreeBAD, and several other OSes >perform, and the things that stuff like Ganglia As a simplification and if you consider that SMP systems are moving to NUMA, the difference is mainly a matter of scale: There is an additional knee in the cost of process migration and RAM access between different CPU cores depending on whether they are on the same chip, different chips within the same host or different hosts. --=20 Peter Jeremy Please excuse any delays as the result of my ISP's inability to implement an MTA that is either RFC2821-compliant or matches their claimed behaviour. --xs+9IvWevLaxKUtW Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.8 (FreeBSD) iEYEARECAAYFAkffgUEACgkQ/opHv/APuIfUeACguWAepUTlcKJNT/ZN6YxUzHad qA8An35Yl5u6XMzMlTWpNKp1/BX2axIM =fxLw -----END PGP SIGNATURE----- --xs+9IvWevLaxKUtW--
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