Updating our TCP and socket sysctl values...

Navdeep Parhar nparhar at gmail.com
Sun Mar 20 01:19:46 UTC 2011

On Sat, Mar 19, 2011 at 5:38 PM, Gordon Tetlow <gordon at tetlows.org> wrote:
> On Sat, Mar 19, 2011 at 4:13 PM, Navdeep Parhar <nparhar at gmail.com> wrote:
>> 256KB seems adequate for 10G (as long as the consumer can keep
>> draining the socket rcv buffer fast enough).  If you consider 2 x
>> bandwidth delay product to be a reasonable socket buffer size then
>> 256K allows for 10G networks with ~100ms delays.  Normally the delay
>> is _way_ less than this for 10G and even 256K may be an overkill (but
>> this is ok, the kernel has tcp_do_autorcvbuf on by default)
> The BDP for a 10Gbps link with 100ms delay is about 120MB.

I meant 100us (microseconds), sorry.  My point still stands - 10G
networks have much less one way delay than this.  The worst  I can
find in the lab right now has around ~30us delay.  A socket rcv
bufsize of 64K maxes out the link in some casual testing with netperf
(with autosizing disabled).  256K is already more than what's needed.


> Here's a decent calculator for figuring it out:
> http://www.speedguide.net/bdp.php
> Regards,
> Gordon

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