***SPAM*** Re: ***SPAM*** Re: [ofa-general] 4K MTU with OpenSM?

[Hal Rosenstock]

On Wed, Mar 18, 2009 at 5:53 AM, Hal Rosenstock
<hal.rosenstock at gmail.com> wrote:
> On Wed, Mar 18, 2009 at 5:44 AM, Sasha Khapyorsky <sashak at voltaire.com> wrote:
>> On 18:17 Tue 17 Mar     , Dave Olson wrote:
>>> On Tue, 17 Mar 2009, Hal Rosenstock wrote:
>>> | On Tue, Mar 17, 2009 at 3:02 PM, Ted H. Kim <Ted.Kim at sun.com> wrote:
>>> | > Is there way to config 4K IB MTU with OpenSM?
>>> | > What's the option of file setting for that?
>>> |
>>> | See the partition configuration section in the man page or
>>> | opensm/doc/partition-config.txt. It's something like:
>>> |
>>> | Default=0x7fff,ipoib,mtu=5:ALL=full;
>>
>> This will use this MTU value for IPoIB multicast group.
>>
>> As far as I understood Ted's question was "how to setup port's MTU using
>> OpenSM". Assuming so I don't think that OpenSM has such functionality
>> now (although it should not be very hard to add).
>
> Do you mean admin the port's MTU ? If so, why would there be such a need ?
>
> The only time it might be needed would be to select a lower MTU than
> the peers support.

In short, if the peer ports both advertise 4K MTU being supported,
then most SMs (including OpenSM) will set the link to run at that.

-- Hal

> That was done for Tavor for a performance issue. Do
> you envision some other need ?
>
> -- Hal
>
>> Sasha
> _______________________________________________
> general mailing list
> general at lists.openfabrics.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general
>
> To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
>