On Mon, 20 Dec 1999, Robert Johannes wrote:
> The reason I ask is because I want to know if there's a perfomance
> difference between them. I've both the tekram DC390F (with the
> "E" extension), and the fireport 40 (with the "J" extension), and I was
> wondering if there's a perfomance difference between the two
> controllers. Do you know?
I don't, but I would want to say the simplest the fastest, but they are
very probably both as fast.
It did happen 1 or 2 years ago that I measured the speed of the SCRIPTS
processor (without on chip SRAM involved) with 810A rev 18, 875 rev 3 and
895 rev 1. 875 and 810A gave about same result (have probably the same
SCRIPTS core) but the 895 was significantly faster (>10%).
The 875 has on chip SRAM but the 810A has to fetch SCRIPTS instructions
from main memory over the PCI BUS. This makes the 875 much more
interesting.
Even the 896 SCRIPTS processor does not beat the 895 SCRIPTS processor.
The 896 is faster when it prefetches SCRIPTS from system RAM but it is
what the sym53c8xx driver does avoid. :)
The 896 has other features as 8K on-chip SRAM (875 abd 895 have 4K),
hardware phase mismatch context, 64 bit PCI, etc ...
Differences due to SCRIPTS processor speed should not make significant
difference for real life. It is likely the on-chip SRAM and the hardware
phase mismatch (896) that make differences, in my opinion, and obviously
the SCSI transfer speed.
G�rard.
> Robert
>
>
> On Mon, 20 Dec 1999, Gerard Roudier wrote:
>
> >
> > On Mon, 20 Dec 1999, Robert Johannes wrote:
> >
> > > Gerard,
> > > Do you know which one of these Symbios chipsets is the latest? The one
> > > with a "J" or the one with an "E"?
> >
> > "E" probably, but the chip revision id should be a more accurate info.
> >
> > - E means that the device supports power management features (not used for
> > now under Linux).
> > - J means that is supports JTAG
> > - N means JTAG support but not big-endian mode that is a never used
> > feature, I think.
> > - B addresses the package (208 pin plastic versus 169 blah blah ...)
> > - Etc ... I don't know the meaning about the other 22 possible letters.;-)
> >
> > Things like J, JB, E, JE, JBE, ... exists.
> >
> > The relationship between chip revision and actual chip type may just not
> > exist. I remind having asked Pamela Delanney from LSI LOGIC a couple of
> > months ago, but it was hard for her to gather the information.;) Further
> > sym/ncr driver versions will display 875 for everything that incorporates
> > one or two 875 cores, for simplicity and in order not to output wrong
> > info.
> >
> > G�rard.
> >
> >
>
>
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