On 14/12/06, Andre Oppermann <[EMAIL PROTECTED]> wrote:
Chris wrote:
> On 12/12/06, Andre Oppermann <[EMAIL PROTECTED]> wrote:
>> This is a patch adding automatic TCP send and receive socket buffer
>> sizing.
>> Normally the socket buffers are static (either derived from global
>> defaults
>> or set with setsockopt) and do not adapt to real network conditions. Two
>> things happen: a) your socket buffers are too small and you can't
>> reach the
>> full potential of the network between both hosts; b) your socket
>> buffers are
>> too big and you waste a lot of kernel memory for data just sitting
>> around.
>>
>> With automatic TCP send and receive socket buffers we can start with a
>> small
>> buffer and quickly grow it in parallel with the TCP congestion window
>> to match
>> real network conditions.
>>
>> FreeBSD has a default 32K send socket buffer. This supports a maximal
>> transfer rate of only slightly more than 2Mbit/s on a 100ms RTT trans-
>> continental link. Or at 200ms just above 1Mbit/s. With TCP send buffer
>> auto scaling and the default values below it supports 20Mbit/s at 100ms
>> and 10Mbit/s at 200ms. That's an improvement of factor 10, or 1000%.
>> For the receive side it looks slightly better with a default of 64K
>> buffer
>> size.
>>
>> The automatic send buffer sizing patch is currently running on one
>> half of
>> the FTP.FreeBSD.ORG cluster w/o any problems so far. Against this
>> machine
>> with the automatic receive buffer sizing patch I can download at
>> 5.7MBytes
>> per second. Without patch it maxed out at 1.6MBytes per second as the
>> delay
>> bandwidth product became equal to the static socket buffer size
>> without hitting
>> the limits of the physical link between the machines. My test machine
>> is about
>> 35ms from that FTP.FreeBSD.ORG and connected through a moderately
>> loaded 100Mbit
>> Internet link.
>>
>> New sysctl's are:
>>
>> net.inet.tcp.sendbuf_auto=1 (enabled)
>> net.inet.tcp.sendbuf_inc=8192 (8K, step size)
>> net.inet.tcp.sendbuf_max=262144 (256K, growth limit)
>> net.inet.tcp.recvbuf_auto=1 (enabled)
>> net.inet.tcp.recvbuf_inc=16384 (16K, step size)
>> net.inet.tcp.recvbuf_max=262144 (256K, growth limit)
>>
>> The patch is available here (it may apply with some fuzz):
>>
>> http://people.freebsd.org/~andre/tcp_auto_buf-20061212.diff
>>
>> Any tests and test reports are very welcome.
>>
>> --
>> Andre
>
> Hi does this patch work on 6.x? I used the send patch on 6.x and works
> great please make a 6.x patch thank you and I will happily test.
No, this patch doesn't work on 6.x. It makes changes to struct tcpcb
to add two additional fields. This requires netstat(1) to be recompiled
and is a ABI change. However I've got a number of requests for 6.x
patch so I may make one anyway.
--
Andre
Please that would be great, the send patch works on 6.x flawlessly and
has improved performance enormously it would be a shame to have to
wait for 7.x to be production ready before I use it.
Thanks
Chris
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