accept filters

Van Vinh Vo vovanvinh2001 at yahoo.com
Sat Jul 19 05:30:50 PDT 2003


Hello all,

I read the notation of accept filter from google, but
i don't well understand, this text as following    

"Versions of FreeBSD from August 2000 onwards include
a feature called "accept filters" which delay the
return from accept() until a condition has been met,
e.g. an HTTP request has arrived. This postpones the
requirement for a child process to handle the new
connection which therefore increases the number of
connections that a given number of child processes can
handle. It also allows a child process to accomplish
more immediately after accept() returns (because the
request is already available to be read) so there is
less context switching.

Accept filters provide the most benefit on servers
that are already so busy that they are configured with
"KeepAlive Off". HTTP KeepAlive (aka persistent
connections) avoids the cost of setting up a new
connection for every request, but connections that are
being kept alive use up one of the available child
processes. Since there is a limited number of child
processes this can significantly reduce the capacity
of the server. The viewers of a web site will still
get a lot of the benefit of persistent connections
even with a very small KeepAliveTimeout so you should
try reducing it before turning it off altogether."

from http://httpd.apache.org/docs/misc/perf-bsd44.html





"accept filter delays the return from accept() until a
condition has been met "

does it mean that it delays the connection of sockct
when the system is processing others instructions ?

"it allows a process to accomplish more immediately
after accept() returns ! what does it mean ? "

does it mean that when a process is rruning, the
system receive a connexion, it delay this connexion
and continue running this process, after that it
accept the connexion !

and how can we configure this accept filters ?

please explain me  

Thanks for your helping     
Vinh 


__________________________________
Do you Yahoo!?
SBC Yahoo! DSL - Now only $29.95 per month!
http://sbc.yahoo.com


More information about the freebsd-net mailing list