Date: Sun, 4 Oct 1998 15:25:28 +0200 From: Eivind Eklund <eivind@yes.no> To: Mike Smith <mike@smith.net.au>, Bruce Evans <bde@zeta.org.au> Cc: Don.Lewis@tsc.tdk.com, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG, gibbs@plutotech.com, tlambert@primenet.com Subject: Re: filesystem safety and SCSI disk write caching Message-ID: <19981004152528.12252@follo.net> In-Reply-To: <199810040706.AAA02436@dingo.cdrom.com>; from Mike Smith on Sun, Oct 04, 1998 at 12:06:15AM -0700 References: <199810040616.QAA26536@godzilla.zeta.org.au> <199810040706.AAA02436@dingo.cdrom.com>
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On Sun, Oct 04, 1998 at 12:06:15AM -0700, Mike Smith wrote:
> > >> Yes, the default configuration may be much slower than mine.
> > >
> > >I can definitely back your basic point ('make world' is CPU bound) up.
> > >On a 4-way Xeon system with slow disks we were still able to get down
> > >around 40 minutes.
> >
> > Er, that shows that it is i/o bound on systems with so much CPU. I
> > got it down to 75 minutes on 1-way K6-233 with 1 IDE disk before it
> > was bloated by perl5 and transition to elf.
>
> Moving to an MFS only saved about 15% of the build time. My point was
> that a faster CPU let you go faster. If the build was I/O bound, it
> wouldn't.
My hypothesis is that for the high end boxes, 'make world' is mostly
bound by memory bandwidth. This is what seems to best match the speed
patterns people have been reporting.
Unfortunately, I can only think of a single way of verifying this:
Running a PPro build in 64-bit mode and 128-bit mode, with the same
amount of the same speed memory. It would require a motherboard that
had 128-bit support; AFAIK, this is only present in the early Intel
boards :-(
Eivind.
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