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Re: What exactly is net.inet.tcp.sockthreshold?
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Re: What exactly is net.inet.tcp.sockthreshold?

  • Subject: Re: What exactly is net.inet.tcp.sockthreshold?
  • From: "Chris McFarling" <email@hidden>
  • Date: Fri, 30 Sep 2005 16:59:34 -0500
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" <email@hidden>
To: "Chris McFarling" <email@hidden>
Cc: <email@hidden>
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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References: 
 >What exactly is net.inet.tcp.sockthreshold? (From: "Chris McFarling" <email@hidden>)
 >Re: What exactly is net.inet.tcp.sockthreshold? (From: Vincent Lubet <email@hidden>)
 >Re: What exactly is net.inet.tcp.sockthreshold? (From: "Chris McFarling" <email@hidden>)
 >Re: What exactly is net.inet.tcp.sockthreshold? (From: "Chris McFarling" <email@hidden>)
 >Re: What exactly is net.inet.tcp.sockthreshold? (From: Vincent Lubet <email@hidden>)

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