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SubjectRe: sendfile+zerocopy: fairly sexy (nothing to do with ECN)
On Sun, Jan 28, 2001 at 02:37:48PM +0100, Felix von Leitner wrote:
> What is missing here is a good authoritative web ressource that tells
> people which NIC to buy.
>
> I have a tulip NIC because a few years ago that apparently was the NIC
> of choice. It has good multicast (which is important to me), but AFAIK
> it has neither scatter-gather nor hardware checksumming.
>
> Is there such a web page already?
> If not, I volunteer to create amd maintain one.

Here a try for FastEthernet. Corrections/additions welcome.

Currently the 3c9xx cards look like the best commonly affordable ones,
at least when you care about zero copy networking. The newer ones have
all the necessary toys for it.
Don't use them with the 3com vendor driver though, their driver is crap.

eepro100 seems to have mostly the same facilities, but Intel doesn't
document it fully so it is not usable in the standard Linux driver. They have
an own driver available (e100.c) which does more, but it of course lags in
progress to the normal stack.

I don't know about starfire, but it seems to be hard to even buy them anyways.

Sun HME seems to be on similar level as 3c9xx, but near impossible to buy or
very expensive.

Realtek is ok for low cost and being relatively hazzle free, but they
miss lots of useful facilities and basically require a copy for RX.

SMC epic/100 is handicapped by not being able to receive to unaligned addresses,
requiring in linux a driver level copy (that may change in 2.5 though, zero
copy has the necessary infrastructure to only copy the header in this case,
not the whole packet)

AMD pcnet afaik doesn't do hardware checksums.

Tulip doesn't do hardware checksum and is a bit constrained by the
required long word alignment in RX (causing problems with misaligned IP
headers, see above on epic100)

Advantage of Tulip and AMD is that they perform much better in my experience
on half duplex Ethernet than other cards because they a modified
patented backoff scheme. Without it Linux 2.1+ tends to suffer badly from
ethernet congestion by colliding with the own acks, probably because it
sends too fast.

-Andi


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