Date: Tue, 16 Jan 2001 10:28:52 -0800 (PST) From: Richard Hodges <rh@matriplex.com> To: Mike Tancsa <mike@sentex.net> Cc: freebsd-atm@FreeBSD.ORG Subject: Re: ATM under 4.x STABLE (DMA and en driver ?) Message-ID: <Pine.BSF.4.10.10101161004200.676-100000@mail.matriplex.com> In-Reply-To: <5.0.1.4.0.20010116121839.033a2a70@marble.sentex.ca>
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On Tue, 16 Jan 2001, Mike Tancsa wrote:
> At 09:18 AM 1/16/01 -0800, Richard Hodges wrote:
> >On Tue, 16 Jan 2001, Mike Tancsa wrote:
> > >
> > > en0: <Efficient Networks ENI-155p> mem 0xfe000000-0xfe3fffff irq 11 at
> > > device 8.0 on pci1
> > > en0: unexpected timeout in rx DMA test
> > > en0: WARNING: DMA test detects a broken PCI chipset!
> > > trying to work around the problem... but if this doesn't
> > > work for you, you'd better switch to a newer motherboard.
> > Your DMA message above seems to refer to the chipset not being able
> > to handle "misaligned 64 byte DMA", which might not be a major
> > problem, but just might reduce the performance.
> Hmmm... Any guesses as to how much of a performance drop ?
Gueses? Sure :-) I think this is referring to the longest burst
of data that the card can push through the PCI bus at a time. Since
you need one PCI cycle for setup, your max PCI throughput would
be roughly 133MB/sec / (4 + burstlen). Obviously, 64-byte bursts
will be more productive than 4-byte bursts (50% wasted) for example.
> BTW, for my simple protocol requirements, should I try and pick up a couple
> of used Fore cards instead ? I am hoping the box will be able to forward
> 30-50Mb/s over its life time.
That should be no problem at all. I rarely see better than 80mb/sec
on an FTP file transfer, but for raw throughput you should be able
to reach 120+ Unless the Efficient card is *really* broken, I assume
you should see comparable results.
-Richard
-------------------------------------------
Richard Hodges | Matriplex, inc.
<title> | 769 Basque Way
rh@matriplex.com | Carson City, NV 89706
775-886-6477 | www.matriplex.com
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