Re: memory performance
On Saturday, 15 May, Martin Lucina wrote:
> I recently got an extra 128MB of memory for my AS200. This has of course
> resulted in a massive performance improvement and I highly reccomend that
> anyone who can afford it have at least 64MB of memory. Today whilst pondering
> over internal SCSI cabling issues and so on I decided to remove the 32MB of
> older (and 70ns) memory to ease up space in the case. I then ran Dhrystone
> with only the new (60ns) memory installed, expecting to see a slight
> performance increase. Instead dhrystone consistently reports ~298000 compared
> to ~300000 previously. Any ideas?
Hmm. By the way, how much memory does Dhrystone use? Can it be that it
fits wholly into Bcache, making memory timings irrelevant? Then (or if
the memory timings are the same for the old and new memory) the
performance difference can be explained by indirect influence of the
memory size change, e.g., through page colouring or stuff like that.
>
> Also, is there any way to determine what the system thinks about the speed of
> the memory installed (wait states, etc...)?
>
Yes. See "DECchip 21071 and DECchip 21072 Core Logic Chipsets Data Sheet",
ftp://ftp.digital.com/pub/DEC/DECinfo/semiconductor/literature/071_72ds.pdf.
Nikita
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