Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!sdd.hp.com!ucsd!nosc!crash!pnet01!lkoop From: lkoop@pnet01.cts.com (Lamonte Koop) Newsgroups: comp.sys.amiga.hardware Subject: Re: Slow GVP '030 accelerator board Message-ID: <5765@crash.cts.com> Date: 21 Nov 90 03:16:01 GMT Sender: root@crash.cts.com Organization: People-Net [pnet01], El Cajon CA Lines: 73 daveh@cbmvax.commodore.com (Dave Haynie) writes: >In article <1990Nov16.175346.4884@maverick.ksu.ksu.edu> yeewei@matt.ksu.ksu.edu (Yee-Wei Huang) writes: > >> I recently purchased a GVP 28mhz '030 accelerator board, and >>it is not performing up to par. > >>GVP 3001 accel card w/o '882 and w/o 32 bit ram > ^^^^^^^^^^^^^^-------- Great Ceasar's Ghost, Superman! Quite agreed here... :^) > >> When I run performance tests on the machine, I show only a 20% >>increase over the stock 68000! > >That's just about what you should expect to see, without any 32 bit RAM. >Without faster and wider memory, the clock speed is going to make very >little difference, the CPU will be memory bound. And, with 16 bit memory, >the 68030 is less efficient than the 68000. 680x0 instructions are >based on 16 bit words, yet the 68030's prefetch mechanism always grabs >32 bits at a time for any instruction fetch, even if the second 16 bits >won't be used. So, on a 68030 with 16 bit RAM, a certain % of the memory >cycles you run do absolutely nothing relative to a 68000. You do get >performance increases as well, thanks to full 32 bit ALUs and better >microcode, but you still don't win in many cases until the caches are >enabled. If you're running with the GVP standard Startup-Sequence, you >will have the data cache turned on too, which should help you out a Dave...this is one I need to disagree with. [Why do I see flames on the horizon? :-)] Of course running in a 16-bit environment is killing a great deal of the performance of the 68030...the extra cycles needed for the bus accesses are quite time consuming. However, the figure of '20%' over a stock 2000 with a standard 68000 I cannot agree on as being correct in any sense. To illustrate, I turned off the 32-bit RAM (well...didn't configure it, so for all intensive puposes it's off) on my 25MHz 030 based system here. My performance figures show the system at 2.1x (or 210%) of a normal 68000-based Amiga....equivalently a 110% increase, not 20%. [This is with the Data cache OFF...with it on, the increase jumps to 200% or so]. These figures are with my term running in the backgound, and several other smaller programs (this is probably not much of a difference...they should all be in a 'Wait' condition anyway). Of course with 32-bit RAM enabled...I get around 7-900%. This is rather a poor way to make my point, but that 20% figure bothers me. If it were the case that it was this bad, there would be little market for the various 68020 accelerators around which have no 32-bit memory facilities...the instruction units on the 020 and 030 are similiar, and have the same basic problem on the 16-bit bus..AND the 020 does not have a nice data cache to help it out... Applicatons-wise, though, I DO agree with around 20-30% though, as benchmarks are far too simple to measure over the entire spectrum of operations. If this GVP board is being tested with any of the benchmarking tests I've seen though (Ronin CPUSpeed, etc...), I'd more expect a reading as I mentioned before. >Really, the only real use for a 68030 without 32 bit RAM would be in >floating point operations, which of course require an FPU. A plain >'030 with no FPU and no 32 bit RAM is about the most expensive way I >can think of to improve your system performance by around 20%. Add some >decent 32 bit memory and you'll see more like 400%-800% improvement. >That's why the A2630 doesn't come without 32 bit RAM. Agreed here...without 32-bit RAM, the 030 is rather like a very expensive chicken without a head.... >-- >Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" > {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy > Standing on the shoulders of giants leaves me cold -REM --LaMonte UUCP: {hplabs!hp-sdd ucsd nosc}!crash!pnet01!lkoop ARPA: crash!pnet01!lkoop@nosc.mil INET: lkoop@pnet01.cts.com