Re: Iperf max b/w


I was recently doing some gigE testing ...  940 Mb/s was a
number I saw with 1500 byte MTU hosts; you may have to go
to 9000 byte MTUs to get 990.

Note that for all of these there must be no loss, with the
bottleneck being the host interface; if you ever get
into TCP's "sawtooth" pattern, the maximum you'll achieve
is ~75% of the raw bitrate and probably much less.

[FWIW, I've done this with a syskonnect gigE card & 64 bit
66 Mhz PCI bus machine; PCI-X should give you more headroom.]

--Matt

--On Friday, October 10, 2003 9:50 AM -0500 Tony Rimovsky <tony --at-- ncsa.uiuc.edu> wrote:

> there could be several host bottlenecks:
>   1.  pci bus speed.
>   2.  other host activity.
>   3.  frame size and io/cpu utilization
>   4.  tcp implimentation problems
>
>
>
>
>
> --On Friday, October 10, 2003 8:36 AM -0600 Cameron Harr <charr --at-- lnxi.com> wrote:
>
>> Tony Rimovsky wrote:
>>
>>> It may be a host limitation.  We've seen iperf perform faster than that
>>> (990 Mbps) on high latency gigabit paths with larger windows.
>>
>> Ok. For my aid, when you say host, are you thinking PCI-X bridge to Gig-E
>> nic (hardware)?
>>
>> --
>> Cameron Harr
>> Systems Engineer
>> Linux Networx Inc
>> http://www.lnxi.com
>
>
>




Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index