Date: Sat, 18 May 2002 13:43:04 +0200 (CEST) From: Attila Nagy <bra@fsn.hu> To: Terry Lambert <tlambert2@mindspring.com> Cc: freebsd-arch@freebsd.org, <freebsd-net@freebsd.org> Subject: Re: HEADS UP: ALTQ integration developer preview Message-ID: <Pine.LNX.4.44.0205181336380.10862-100000@scribble.fsn.hu> In-Reply-To: <3CE61675.BCE2A9E1@mindspring.com> References: <Pine.BSF.4.10.10205170216500.29826-100000@ady.warpnet.ro> <Pine.LNX.4.44.0205171056200.2091-100000@scribble.fsn.hu> <3CE55A9B.73EA3DE4@mindspring.com> <Pine.LNX.4.44.0205181018300.10011-100000@scribble.fsn.hu> <3CE61675.BCE2A9E1@mindspring.com>
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Hello, > Sending datagrams bigger than the MTU is a bad idea. It depends on what do you want to do with that NFS server :) I want to get out from that several hundred megabits per second, so I can't use <1500 bytes MTU. Just for comparison: when using <1500 bytes MTU (as close as possible to the limit) I can achieve about 1-1.5 MBps throughput. When using 32768 bytes MTU I can get around 190 Mbps out from a PIII 450. (and only 190 Mbps because the two frontends have fast ethernet cards) So why this is so bad? If the other end can keep up, it will increase throughput. BTW, the default UDP readsize is above 1500 bytes, so I couldn't use the server with a simple NFS mount. When I replaced the gx driver to em it just started to work. Now I am using TCP and 32k readsize with 64k tcp.sendspace and recvspace (I could nearly double the performance with setting these from the default values). So I am happy with it, I just took a note that the gx driver has some problems in these cases. > I would be real tempted to drop the packets and send "don't fragment" > ICMP responses to beat up anyone who abused UDP by sending larger than > the MTU. That's another point. I want performance :) > I guess this is about Linux UDP NFS clients, in particular. Nope, both the server and the client side is FreeBSD stable. --------[ Free Software ISOs - ftp://ftp.fsn.hu/pub/CDROM-Images/ ]------- Attila Nagy e-mail: Attila.Nagy@fsn.hu Free Software Network (FSN.HU) phone @work: +361 210 1415 (194) cell.: +3630 306 6758 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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