Date: Sat, 15 Dec 2001 13:49:49 EST From: TD790@aol.com To: hackers@freebsd.org Cc: isp@freebsd.org Subject: Re: 3Com driver problems Message-ID: <9d.200f9846.294cf54d@aol.com>
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In a message dated 12/15/2001 1:07:28 PM Eastern Standard Time, "."@babalo.ru writes: > At 06:41 PM 12/14/2001, you wrote: > >HP889@aol.com writes: > > > Try to front end your machine with a switch...the 5 cards is most > > likely your > > > problem. With each device you increase your bus contention (ie worsen > the > > > worst case bus master scenario)...either that or get a 4 port card that > is > > > more efficient than 5 individual cards. > >I have some opposite expierence. > >This is my biggest router: > >0gw~(1)>uname -a > >FreeBSD gw.pike 4.4-STABLE FreeBSD 4.4-STABLE #0: Wed Sep 19 06:29:38 MSD > >2001 babolo@shikster.pike.ru:/tmp/babolo/usr/src/sys/gw i386 > >0gw~(2)>ifconfig -a > >dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >dc1: flags=8802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500 > >dc2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >dc3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >xl1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >xl2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > >6 used 100 M ethernet interfaces among others. > >dc0..dc3 is one card. > >xl0 cards are workaround for the fact that processor > sty > >spent MUCH more time in interrupt state with dc driver > >than with xl driver with the same load. > >Yes, I try find xl x 4 card but no success Interrupt state and bus contention are 2 different problems...the problem with referencing the dc driver is that there are lots of different cards with different results. btw, the if_dc driver is one of the drivers optimized for the alpha (note the m_devget calls)..and can use a bit of tuning. my experience with dlink quad cards and xl is that they are similar in performance if you account for the fact that the quad cards are going through a pci bridge chip...and the reduction in bus contention versus using 4 cards. One issue is that you (and alot of others) dont understand the physical limits of your machine. putting 6 or more 100Mb/s ethernets on one 32bit bus is simply asking for problems. You are dealing with a bus that BURSTs to a bit more than a Gb and probably no more sustained throughput capability than 500Mb/s (with 2 cards you'll get some errors at 400Mb/s and down from there as you add cards)...so how do you expect to handle worst case DMA requirements of 600-800Mb/s in half duplex or twice that if you run 100Mb/s full duplex? Its just not physically possible. DB To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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