Date: Mon, 16 Jul 2001 09:57:22 -0700 (PDT) From: wpaul@FreeBSD.ORG (Bill Paul) To: silby@silby.com (Mike Silbersack) Cc: hackers@freebsd.org Subject: Re: NatSemi DP83820 gigE driver kit for 4.2 and 4.3 Message-ID: <20010716165722.EA84737B401@hub.freebsd.org> In-Reply-To: <20010715204819.N769-100000@achilles.silby.com> from Mike Silbersack at "Jul 15, 2001 08:49:19 pm"
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> > On Fri, 13 Jul 2001, Bill Paul wrote: > > > For those who have gigabit ethernet NICs based on the National > > Semiconductor DP83820 and DP83821 controller chips and want to use > > them with FreeBSD 4.2 and 4.3, there is a driver kit now available > > at the following URL: > ... > > These cards are all extremely cheap (some can be had for under $100) > > and fairly easy to find. (I now have one in my workstation.) They could > > potentially become extremely popular, which is why I'm making a driver > > retrofit kit available. Anyone running a recent 4-STABLE or 5.0-CURRENT > > system should already have the necessary driver support. > > How do these perform compared to the more expensive gigabit cards? > > Mike "Silby" Silbersack > They're "okay." The NatSemi chip has one flaw, which is that RX buffers must be aligned on a 64-bit boundary. None of the more expensive NICs have this restriction. The correct way to deal with this is to copy frames on receive to fixup the alignment, but I decided to make this conditional for this driver: on the i386 platform, the driver omits the copy since unaligned accesses are allowed, and the performance hit for copying is severe when you're using jumbo frames. On the alpha, you have to do the copy. The chip has some nifty features though: hardware VLAN tag insertion and removal, TCP/IP checksum offload on receive and transmit, 2048-bit multicast hash filter, and 4 pattern match buffers for use with WOL. The transmit checksum offload has to be turned off if you use jumbo frames larger than about 8K, because the chip only has an 8K transmit FIFO. There is also support for interrupt moderation. For $90 to $120, they're a good bargain. You should be able get at least 300 to 400Mbps on good x86 hardware (with TCP). -Bill To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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