Hi Roamer
What's the reasoning behind EOLing the MDT? Claiming support for
LSO as the alternative is premature, given only one vendor claims support
for it now. I have support for LSO for TCP currently in the hardware
but is limited to only 64K, likewise if UDP gets implemented in our
firmware, (not available now). MDT is much better it has no such
limitations and therefore yields better performance with what we have
now, both in terms of existing hardware and version of Solaris.
Our next gen hardware will support larger LSO size but that's not
going to be this year, or I expect the Solaris 11 release timeframe.
I would really appreciate that you could re-consider EOLing MDT
at least until the UDP LSO support in our hardware overtakes the
performance benefit provided by MDT.
Frank
Yunsong (Roamer) Lu wrote:
> Frank,
> The current LSO implementation in Solaris is only for TCP. MDT was
> implemented with both TCP and UDP. But the plan is to implement UDP
> LSO and to EOL MDT in the near future, so you may consider whether to
> support UDP LSO on your hardware.
>
> The software interface for UDP LSO will be similar to TCP LSO but
> slightly different since IP fragmentation instead TCP segmentation
> will be done by the hardware.
>
> Thanks,
>
> Roamer
>
>
> Francesco DiMambro wrote:
>> Hi Meem
>> I tried a dtrace probe in my driver around the MDT tx, and it's
>> definitely being called during a quick 'netperf -t UDP_STREAM',
>> test.
>>
>> 1 31510 sge_multidata_xmit:return
>> 1 31509 sge_multidata_xmit:entry
>> 1 31510 sge_multidata_xmit:return
>> 1 31509 sge_multidata_xmit:entry
>> 1 31510 sge_multidata_xmit:return
>> 1 31509 sge_multidata_xmit:entry
>> 1 31510 sge_multidata_xmit:return
>> 1 31509 sge_multidata_xmit:entry
>> 1 31510 sge_multidata_xmit:return
>>
>> With that same test UDP can transmit at twice the perf of MDT
>> off, not to bad at all. Since you mentioned the competition, of course
>> I need to ask more questions, does the Solaris UDP stack support
>> LSO for UDP. I talked to the HW guys here and they say it can be
>> done once we know the software interface, looking at the code the
>> only parameters it gives the driver for LSO is a flag to say the packet
>> is LSO and the MSS. Is that the only software interface needed to
>> do UDP LRO? Seems like it would be but I want to make sure.
>>
>> cheers
>> Frank
>> Peter Memishian wrote:
>>> > LSO doesn't work as well as MDT, Also the hardware I'm
>>> working with
>>> > has no UDP LSO capability, does any?
>>>
>>> I don't see any support in our UDP module for MDT. Others more
>>> familiar
>>> with the latest hardware could speak to the UDP LSO question, but I'd
>>> heard rumors that some Neterion ASICs could do it.
>>>
>>> --
>>> meem
>>>
>>
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>
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