Date: Fri, 5 Nov 1999 10:29:27 -0800 (PST) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: ejs@bfd.com (Eric J. Schwertfeger) Cc: adams@digitalspark.net (Adam Strohl), doconnor@gsoft.com.au (Daniel O'Connor), darrylo@sr.hp.com (Darryl Okahata), freebsd-smp@FreeBSD.ORG Subject: Re: Dual Celeron + FreeBSD? Message-ID: <199911051829.KAA57885@gndrsh.dnsmgr.net> In-Reply-To: <Pine.BSF.4.10.9911050836470.14598-100000@harlie.bfd.com> from "Eric J. Schwertfeger" at "Nov 5, 1999 08:45:04 am"
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> On Thu, 4 Nov 1999, Adam Strohl wrote:
>
> > In the real world the 1/2 the cache at 2x the speed makes all of JACK
> > in performance difference from the "real" PIIs. It rocks.
>
> I agree for the most part, on single-processor machines, though it's
> actually a quarter the cache. The reduced, faster cache causes a single
> celeron to be more memory-bandwidth sensitive. An SMP machine, however,
> has two CPUs contending for the same bandwidth, and for some processes,
> that can be fatal.
>
> I've done make buildworld's on both my dual Celeron and my dual PPro (the
> ones with 512K cache). The difference between single and dual celeron is
> minimal, about 10%. On the dual PPro machine, the speed improvement,
> using the same disk subsystem, was 80%. Yes, on processes that aren't
> memory intensive, dual Celerons rock. In fact, on most things, I see
> closer to 40-50% improvement with dual Celerons, the make buildworld is
> rather memory intensive.
Actually make buildworld is disk intensive... SMP plain out does not
seem to help it much, unless of course you run a non-standard make
world with -pipe, which then does make the memory bandwidth demand
higher, and if both sides of the pipe just happen to get split accross
2 processors it causes the small cache to be ineffective and the memory
system to be a major stall point.
Raid 1 (mirroring) with 3 disk drives tends to help it more than anything...
single or dual processor. Or properly splitting /usr/src, /usr/obj and
${DESTDIR} to 3 spindles does wonders on any type of cpu, even an old
Pentium 100 sees a big improvement...
--
Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net
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