cvs commit: src/etc devd.conf src/sys/modules Makefilesrc/sys/modules/vge Makefile src/sys/dev/vge if_vge.c if_vgereg.hif_

[Ruslan Ermilov]

On Fri, Sep 10, 2004 at 10:15:58PM +0000, Bill Paul wrote:
> > How well designed is the VT6122?  Is it good or more on the 'it works' side?
> 
> It's "ok." I only have a 33Mhz/32-bit PCI sample card. When I tested
> it, I only got it up to about 540Mbps. I attribute some of this to
> 5.3-BETA3's (lack of) performance. :( I was only able to get about
> 120000 frames/sec transmit frame rate out of it, which disappointed
> me. (It should be closer to 400000, especially on a dual PIII 1.2Ghz
> system.)
> 
Did you also test in polling mode?

> RX DMA descriptors _must_ be replentished 4 at a time, because the
> chip apparently caches them 4 at a time. You won't notice this until
> you get a "ran out of RX descriptors" condition, in which case the
> chip's DMA logic can get oddly out of sync (once you re-enable the
> RX ring, it will update the status words for descriptor (X) but put the
> received packet data in the buffer attached to descriptor (X - 2)).
> 
How I love these /* We've fallen behind the chip: catch it. */

> The irritating thing is this requirement is not documented in the
> chip manual.
> 
Who would doubt?  :-)


Cheers,
-- 
Ruslan Ermilov
ru at FreeBSD.org
FreeBSD committer
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