[vortex] 3C905CX, 2.2.18, Dell Dimension 4100 (P933) ReceiveFailure
Fix / Inquiry
Wed, 17 Jan 2001 02:03:02 -0800
Donald Becker wrote:
> On Tue, 16 Jan 2001, Samuel Madden wrote:
> You misunderstand the loops. They are not software timing loops. They
> are PCI transaction counts. PCI transactions are often the most
> appropriate measure.
> > I'm wondering:
> > 1) why isn't some more precise timing mechanism being used here?
> Most of the operations should take zero apparent time. I check the loop
> count for all operations when I write a driver, and it's rare that a
> chip actually requires more than one loop iteration.
If it's rare for a device to take more than one PCI transaction to do
something, do you think the ~30000 transaction count for RxReset on the
3c905cx means the current driver doesn't init the card correctly? Or is
the new chip just slow on that command?
> The loop counts exist to make certain the driver doesn't hang on broken
> or missing hardware.
> > 2) what are the performance implications of making the rx timeouts
> > significantly higher?
> Bad. The kernel is sitting in a very long timing loop. In some cases
> this occurs with many interrupts blocked due to rotating interrupt
But the longer loop is only used on TxReset, RxReset, TotalReset,
DownStall and RxDiscard. Aren't these commands sent very rarely?
(referring specifically to the 2.2.19-pre2 driver with Adam M's
> The patches that increase the timing loop counts are for experimental
> and verification purposes only. Please do not submit them for
> inclusion in a main-line kernel!
> > 3) does anyone have suggestions for what optimal values might be here? i've
> > increased them quite a lot and am not really interesting in trying
> > all the permuations manually.
> Not for the CX board -- some aspect of the design appears to have
> changed dramatically from the earlier chips.
I recently purchased 6 of the Dells with this card. We will be writing
networking software on 'em. This tends to make having a reliable NIC
kind of nice. Should I yank the cards and get something else? If so,
I don't suppose anyone has heard anything from 3com?
"Computer games don't affect kids, I mean if pac man affected us as
kids, we'd all be running around in darkened rooms, munching pills
and listening to repetitive music." --Unknown