Date: Fri, 8 Mar 1996 14:21:44 -0800 From: Matthew Dillon <dillon@backplane.com> To: "Garrett A. Wollman" <wollman@lcs.mit.edu> Cc: bugs@FreeBSD.ORG Subject: Re: bug in netinet/tcp_input.c Message-ID: <199603082221.OAA00262@apollo.backplane.com>
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:<<On Fri, 8 Mar 1996 12:36:15 -0800, Matthew Dillon <dillon@backplane.com> said:
:
:> Hmmm. Then what is the use of -recvpipe and -sendpipe ?
:
:As I said before, they are to set the default buffer size. Anything
:more complicated than that voids your warranty...
:
:-GAWollman
:
:--
:Garrett A. Wollman | Shashish is simple, it's discreet, it's brief. ...
:wollman@lcs.mit.edu | Shashish is the bonding of hearts in spite of distance.
:Opinions not those of| It is a bond more powerful than absence. We like people
:MIT, LCS, ANA, or NSA| who like Shashish. - Claude McKenzie + Florent Vollant
I guess you people aren't aware of the tricks many people play at all
levels to utilize their bandwidth better. I'll describe two of them:
(1) T1 connected host - 1.5 Mbps
(2) frame connected host - 128K frame
(3) modem connected host - 28.8 / telecommuting and serving ftp/www
In all cases, the host is often dealing with SMTP, FTP, news feeds,
and so on, yet must also support one or more users.. in the case
of a small frame connected ISP, perhaps a dozen or two online users.
It is possible to use the route table to adjust recvpipe and sendpipe
buffer sizes on a per destination basis (and mss as well
if you fix your code).
Why would one want to do this? Simple: In order to be able to
run SMTP, FTP, newsfeeds, and other services without impacting
your users. You can set up the route table to automatically
use a smaller mss and smaller buffer size (reducing pipelining and
thus reducing buffering problems for incoming packets).
The only alternative is to hack sendmail, hack ftp, hack apache,
hack news, and hack the umpteen other programs to do a socket opt
to reduce the buffer size, and even that does not work with the MSS
negotiation for incoming connections.
What does this give you? This allows you to saturate your link without
degrading interactive performance over the same link.
Now, unless everyone and his mother has a personal T3, being able to
adjust the mss and receive and send pipes on an individual basis is
an incredibly powerful tool for reaching that state.
Stop thinking small... think BIG! Turn those braindead features into
something more useful.
-Matt
Matthew Dillon Engineering, BEST Internet Communications, Inc.
<dillon@apollo.backplane.com>
[always include a portion of the original email in any response!]
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