Re: question about the set tcp window size in iperf 1.6.3
Hi Kevin,
> you are using the "internet" to run the tests. What kind of "internet"
> connection do you have at both nodes? Often DSL and other internet
> connections do not have symmetric bandwidth ratings, eg. 1.5M down 512K
Box A is connecting via CableModem!!!, BoxB is in a university connection
via
a high-speed education network. That's it!
I'll move box A to another university later this week and give more tests...
> Also a semi-confusing thing is that the kernel decides what the window
> will be, not the application. The SO_SNDBUF/SO_RCVBUF socket settings
> change the send/recieve buffer sizes not advertised window sizes.
> Typically there is a one to one correspondance between the two, but not
> always. Also newer linux kernels do autotuning if and only if window sizes
> (socket buffers) are not explicitly given via the SO_SNDBUF/SO_RCVBUF. Any
> or all of these things could be causing very different readings in one
> direction verses the other.
So if I setup the buffer size to the default value using -w option, should
that disable the autotuning?
Also, Linux autotuning sounds like a black box. Is that the web100/Net100
project?
On their web-site the patch is aivailable for Linux 2.4.19. So if I don't
use that patch,
there is no autotuning, am I right? Or Linux has other algorithms? How could
I know
it's enabled or not?
Thank you all for the help,
-Chong
--
Mitch Kutzko | mitch --at-- dast.nlanr.net | mitch --at-- ncsa.uiuc.edu | 217-333-1199
http://hobbes.ncsa.uiuc.edu/