Subject: Re: PC164 memory bus speeed (was: pciide performance on alpha)
To: None <>
From: Simon Burge <>
List: port-alpha
Date: 08/13/1999 23:37:20
Jason Thorpe wrote:

> On Thu, 12 Aug 1999 12:48:00 -0500 (CDT) 
>  Dave Huang <> wrote:
>  > I assume the PC164's memory bus is only faster than the 164LX when all 8
>  > SIMM slots are filled? How fast is it anyways? I took a quick look at the
>  > PC164 technical reference manual and didn't see any mention of the memory
>  > bus speed, only the PCI bus speed.
> Yes, that's correct.  All slots must be filled on the PC164 for it to be
> better than the 164LX.

I've gotta say I'm a bit disappointed in Luke's new 500MHz PC164 - it's
got 8x 32MB simms, but still memory performance seems lacking.  I've
got a memory-bound benchmark (it's actually some production code that's
so crappy it's a good benchmark, but I can't distribute it).  On the
PC164 it takes 25.87 seconds, but only 12.13 seconds on the 500/333 that
DEC put on the internet for people to use years ago.  An AlphaServer
4000/710 finished in 15.79 seconds.  (I hope the model numbers make
sense - I'm not really an alpha person.)

lmbench's memory bandwidth and latency figures also seem a little on
the slow side - 149MB/s read and 129MB/s write.  I don't have any other
Alpha results to compare against, but a PentiumII/400 gets 289MB/s read
and 175MB/s write.

Has anyone else got better figures than this?