I asked about the relative speeds of our new 4/233's vs the older
3000/400's, and why we were seeing the newer machines being outperformed
by the old.
It turns out that the DEC salescritter was feeding us marketing when he said
they'd be faster.
Dave Cherkus <cherkus_at_UniMaster.COM> wrote:
> That's because some people think that all the world does with these
> newfangled workstations is run SPECint and SPECfp. Reality has
> outpaced these benchmarks.
>
> In particular, the 3000/400 has an excellent workstation class main
> memory system. The 4/233 is an Alpha chip mated with a PC chassis so
> the main memory bandwidth is disappointing. In raw numbers, the
> 3000/400 main memory bus is 256 bits wide (wider than any other Alpha
> box, including 7000 and 2100) whereas the 4/233 has a 64 bit main
> memory bus. This is where the big difference is.
>
> This is also why I won't buy any of the 4/xxx boxes. If I want a PC
> main memory system, I'd buy a PC. As USENET folklore states, to a
> first order approximation UNIX *is* bcopy(). Besides, a Pentium
> is more than capable of saturating a 64 bit memory bus.
Dr. Tom Blinn <tpb_at_zk3.dec.com> commented that the machines are PCI vs
Turbochannel, and the TC machines are probably a faster bus, and the
(cheaper) disk controllers in the 4/233's are probably also slower.
Selden E. Ball, Jr. <SEB_at_LNS62.LNS.CORNELL.EDU> sent me some entries for
/etc/sysconfigtab to help with the I/O performance. I've appended these
to this mail. I havent had a chance to measure before and after numbers
yet.
Jyotinath <jyoti_at_qcav02.enet.dec.com> sent me the Performace Flash for
the AlphaStation Family of machines. Interestingly, while the CPU speed
(SPECfoo) benchmarks are reported, all the multiuser AIM benchmarks are
down as 'nr' (not reported). Selective reporting, maybe? :)
Thanks to the above folks and everyone else who responded with
information... it looks like we'll just have to cope with the systems. I
wont be buying any more of the PCI-based alphas for a while, I'll stick
with the tried and trusted 3000 series machines.
Anthony
=================================================
Selden's /etc/sysconfigtab entry.
vm:
ubc-minpercent = 5
ubc-borrowpercent = 25
ubc-maxpercent = 100
vm-ubcseqpercent = 10
vm-ubcseqstartpercent = 40
vm-ubcpagesteal = 32
vm-ubcdirtypercent = 10
vm-page-free-min = 20
vm-page-free-target = 128
vm-page-free-optimal = 96
vm-page-free-reserved = 10
Received on Mon Jan 09 1995 - 21:52:36 NZDT