ru.unix.bsd

 
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 From : Slawa Olhovchenkov                   2:5030/500     09 Mar 2007  02:40:48
 To : All
 Subject : Вести с полей
 -------------------------------------------------------------------------------- 
 

 
 andre       2007-02-01 18:32:14 UTC
 
   FreeBSD src repository
 
   Modified files:
     sys/netinet          tcp_input.c tcp_output.c tcp_usrreq.c
                          tcp_var.h
   Log:
   Auto sizing TCP socket buffers.
 
   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.
 
   New sysctls 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)
 
   Tested by:      many (on HEAD and RELENG_6)
   Approved by:    re
   MFC after:      1 month
 ... Это настоящий сакс! Причем в очень хорошем состоянии.
 --- GoldED+/BSD 1.1.5
  * Origin:  (2:5030/500)
 
 

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