site_archiver@lists.apple.com Delivered-To: Macnetworkprog@lists.apple.com Is there a way to force AFP to use a specific window size? Long story short...when two Gb OS X clients send simultaneously to our XServe (via AFP), the transfer rate for each drops to about 6MB/s. (when either machine is sending by itself, the transfer rate is ~ 30-40MB/s). I've duplicated this behavior with iperf as well. Using iperf, I've found that by decreasing the window size, the performance is dramatically improved. I would love to be able to make AFP use a smaller window size as well, at least to test and see if it makes a difference. ----- Original Message ----- From: "Vincent Lubet" <vlubet@apple.com> To: "Chris McFarling" <cmcfarling_lists@pacificpremedia.com> Cc: <Macnetworkprog@lists.apple.com> Sent: Friday, September 30, 2005 4:35 PM Subject: Re: What exactly is net.inet.tcp.sockthreshold?
Chris,
The sysctl variables net.inet.tcp.recvspace and net.inet.tcp.sendspace are the default values for the TCP socket buffers that are used to determine the window size. A program is free to override those default values by using the socket options SO_RCVBUF and SO_SNDBUF -- that's what the AFP does.
Vincent
On Sep 30, 2005, at 1:45 PM, Chris McFarling wrote:
**This is an addition to my previous post**
I tried the same test as mentioned previously but mounted the volume on the client via SMB. This time the TCP window size that I had manually specified (18824) was used. So it appears that AFP has it's own way of dealing with window sizes. How can that be affected?
SMB PACKET TRACE
13:36:20.014410 IP 192.168.10.121.50119 > 192.168.10.13.139: . 13579:15027(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014456 IP 192.168.10.13.139 > 192.168.10.121.50119: . ack 15027 win 18824 <nop,nop,timestamp 3550899915 3574083461> 13:36:20.014905 IP 192.168.10.121.50119 > 192.168.10.13.139: . 15027:16475(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014907 IP 192.168.10.121.50119 > 192.168.10.13.139: . 16475:17923(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014910 IP 192.168.10.121.50119 > 192.168.10.13.139: . 17923:19371(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014912 IP 192.168.10.121.50119 > 192.168.10.13.139: . 19371:20819(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014915 IP 192.168.10.121.50119 > 192.168.10.13.139: . 20819:22267(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014917 IP 192.168.10.121.50119 > 192.168.10.13.139: . 22267:23715(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014920 IP 192.168.10.121.50119 > 192.168.10.13.139: . 23715:25163(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014923 IP 192.168.10.121.50119 > 192.168.10.13.139: . 25163:26611(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014925 IP 192.168.10.121.50119 > 192.168.10.13.139: . 26611:28059(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014927 IP 192.168.10.121.50119 > 192.168.10.13.139: . 28059:29507(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014930 IP 192.168.10.121.50119 > 192.168.10.13.139: . 29507:30955(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.014951 IP 192.168.10.13.139 > 192.168.10.121.50119: . ack 30955 win 18824 <nop,nop,timestamp 3550899915 3574083461> 13:36:20.015119 IP 192.168.10.121.50119 > 192.168.10.13.139: . 30955:32403(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015121 IP 192.168.10.121.50119 > 192.168.10.13.139: . 32403:33851(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015124 IP 192.168.10.121.50119 > 192.168.10.13.139: . 33851:35299(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015177 IP 192.168.10.13.139 > 192.168.10.121.50119: . ack 35299 win 18824 <nop,nop,timestamp 3550899915 3574083461> 13:36:20.015345 IP 192.168.10.121.50119 > 192.168.10.13.139: . 35299:36747(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015347 IP 192.168.10.121.50119 > 192.168.10.13.139: . 36747:38195(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015349 IP 192.168.10.121.50119 > 192.168.10.13.139: . 38195:39643(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015351 IP 192.168.10.121.50119 > 192.168.10.13.139: . 39643:41091(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015353 IP 192.168.10.121.50119 > 192.168.10.13.139: . 41091:42539(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015355 IP 192.168.10.121.50119 > 192.168.10.13.139: . 42539:43987(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015357 IP 192.168.10.121.50119 > 192.168.10.13.139: . 43987:45435(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015359 IP 192.168.10.121.50119 > 192.168.10.13.139: . 45435:46883(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015362 IP 192.168.10.121.50119 > 192.168.10.13.139: . 46883:48331(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015364 IP 192.168.10.121.50119 > 192.168.10.13.139: . 48331:49779(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015366 IP 192.168.10.121.50119 > 192.168.10.13.139: . 49779:51227(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015368 IP 192.168.10.121.50119 > 192.168.10.13.139: . 51227:52675(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet 13:36:20.015389 IP 192.168.10.13.139 > 192.168.10.121.50119: . ack 52675 win 18824 <nop,nop,timestamp 3550899915 3574083461> 13:36:20.015557 IP 192.168.10.121.50119 > 192.168.10.13.139: . 52675:54123(1448) ack 537 win 65535 <nop,nop,timestamp 3574083461 3550899915> NBT Packet
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