Re: Celistica with AMD chip-set

[Richard B. Johnson]

On Mon, 30 Aug 2004, Arthur Perry wrote:

> Hello Alan and Richard,
>
> I have to advise caution here, as it is currently unconfirmed whether or
> not the PCI bridge configuration is "incorrect", and that it has "very
> poor PCI performance".

The crapiest 33MHz, 32-bit PCI/Bus in lowly '486 machines hanging
around the lab will beat the Celistia hands-down.

> Unless everyone in the whole wide world is setting this value and we are
> the only ones who are not, I find it hard to believe that this statement
> is not overspeculative.
>

Really?  Well somebody from Salem New Hampshire wrote email to
one of my zillions of managers claiming that this was the "fix".

I was forced to make this "fix" and it "fixed" it. Further,
every "^!&@*$%^!_*(@" so called software, hardware, and whatever
"Engineer......" If that's the correct word, required (demanded)
to see the source code because they were "sure" that " had screwed
up.

To date, there has been no such finding of screw-ups on my part.
FYI, it's really difficult to screw up a "(@#%^P_*!@&#" DMA!

Other machines are able to DMA at over 130 megabytes/second. The
boxes in question run at only 50 megabytes/second.

> The proper place for this should be in the BIOS, if it is indeed a true
> optimization point.
> But until that is positively identified, we should not assume that
> applying this globally for everyone is the right thing to do.
> As in any assumed optimization for a simgle case, it could potentially
> cause performance degradation in somebody else's HBA.
>

Not so.

> This is a cache optimization.
>
> Have you considered the possibility of this "optimization" causing a
> performance hit with Mellanox's PCI implementation?
>

I published a "fix" for the abysimal PCI performance on that
piece of crap. If you don't like it then so what. Fix the
damn box.

> What about people who have already tailored their device driver to work
> well in on this chipset and currently use "read multiple" rather than
> "read cacheline". This optimization could potentially cause a slight
> degradation of performance for them.
>

I don't give a damn.  The box has no DMA capability as it is.
One might as well just use a wet string top communicate with
the PCI boards. The "fix" forced upon me by you guys is now
somehow incorrect?

Go to hell.

>
> Arthur Perry
> Linux Systems/Software Architect
> Lead Linux Engineer
> CSU Validation Group
> Celestica, Salem, NH
> aperry@xxxxxxxxxxxxx
>


Cheers,
Dick Johnson
Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips).
            Note 96.31% of all statistics are fiction.

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