Cap on network speed in CURRENT?
Brooks Davis
brooks at one-eyed-alien.net
Tue Jun 1 17:03:06 PDT 2004
On Tue, Jun 01, 2004 at 03:38:18PM -0700, Luke wrote:
>
> I've got a 100Mbps LAN with ethernet cards that should be capable of using
> it, yet the highest transfer rates I seem to be able to get out of my
> FreeBSD box are 260KB/s receiving and 341KB/s sending with around 200KB/s
> being more normal.
>
> I realize that there are hundreds of factors that could be influencing
> this, but I came across this recent article that made me wonder if this is
> some kind of hardcoded limit:
> http://www.freebsd.org/news/status/report-jan-2004-feb-2004.html#Automatic-sizing-of-TCP-send-buffers
>
> Is this article saying that my network speed is limited by a small
> static TCP buffer size? If so, is there some way that I can increase that
> buffer size to improve performance? The primary function of this machine
> is to move large amounts of data across my network, so I'm willing to
> experiment with increasing the buffer size if it's not too difficult.
On a LAN, buffer size has minimal effect except at very high speeds.
Without tuning, two 5.x boxes with gigabit interfaces connected to a
Cisco 6513 switch (one 5/10/04 and one 2/20/04) reached 187Mbps in
iperf. You're problems symptoms sound like duplex mismatch or bad
hardware to me.
-- Brooks
--
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4
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