[openib-general] [openfabrics-ewg] OFED 1.1 release - schedule and features

[Michael Krause]

At 09:48 AM 7/12/2006, Jeff Broughton wrote:
>Mike,
>
>The whole purpose of SDP is to make sockets go faster without having to 
>have the applications modified.  This is what the customers want.  I've 
>heard this time and time again, across a wide spectrum of customers.

I am well aware of this.  However, Linux / Unix do not support async 
communications which severely limits the potential performance benefits of 
SDP.  When we wrote the SDP specification it was fully understood that 
optimal performance is achieved through async communications.   We spent 
considerable time constructing SDP to support both synchronous and 
asynchronous communication paradigms which there are many applications that 
would benefit.   Customers want to be able to use RDMA interconnects 
without recompilation and through the use of SDP and shared libraries this 
is certainly practical to execute.  Developers however are not the same as 
customers and it is developers who would benefit from the Sockets 
extensions and this would in turn benefit customers.

>Modifying the sockets API is just defining yet another RDMA API, and we 
>have so many already....

I disagree.  This effort has distilled the API to basically one for RDMA 
developers.  Applications are supported over this via either MPI or 
Sockets.    It seems rather self limiting to think the traditional BSD 
synchronous Sockets API is all the world should be able to use when it 
comes to Sockets.  Sockets developers could easily incorporate the 
extensions into their applications providing them with improved designs and 
flexibility without having to learn about RDMA itself.  If the couple of 
calls necessary to extend this API to support direct RDMA would allow them 
to eliminate SDP entirely, well, that has benefits that go beyond just its 
all Sockets; it also eliminates the IP cloud that hovers over SDP 
licensing.   Something that many developers and customers would appreciate.

In the end, this effort could choose to progress Sockets technology and 
extend the number of developers and applications that can achieve optimal 
performance with only minor knowledge growth or they can live with the 
limitations of the BSD Sockets API and either accept performance loss or be 
forced to jump through the hoops of using other rather niche or obscure API 
to accomplish what is possible with a small number of Sockets extensions 
which were defined by people with years of experience implementing Sockets 
and working with application developers.

Mike

>
>-Jeff
>
>
>----------
>From: openfabrics-ewg-bounces at openib.org 
>[mailto:openfabrics-ewg-bounces at openib.org] On Behalf Of Michael Krause
>Sent: Wednesday, July 12, 2006 9:23 AM
>To: Tziporet Koren; Scott Weitzenkamp (sweitzen)
>Cc: OpenFabricsEWG; openib
>Subject: Re: [openfabrics-ewg] [openib-general] OFED 1.1 release - 
>schedule and features
>
>At 12:59 AM 7/12/2006, Tziporet Koren wrote:
>>Scott Weitzenkamp (sweitzen) wrote:
>> > For SDP, I would like to see "improved stability" (maybe you have this
>> > in mind under "beta quality"), also how about "AIO support"?  The rest
>> > of the list looks good.
>> >
>>Yes - beta quality means improved stability.
>>AIO is not planed for 1.1 (schedule issue). If needed we can add it to 1.2
>
>Would be nice if people thought about implementing the Sockets API 
>Extensions from the OpenGroup.  They provide explicit memory management 
>and async communications which will allow SDP performance to be fully 
>exploited.   The benefits go beyond what is found in AIO or on other OS 
>such as Windows.  If one were to extend slightly to have explicit RDMA 
>Read and Write from the Sockets API, then it would be quite possible to 
>eliminate SDP entirely for new applications leaving SDP strictly for 
>legacy Sockets environments.
>
>Mike
>
>
>>Tziporet
>>
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