[dat-discussions] [openib-general] [RFC] DAT 2.0 immediatedataproposal

[Kanevsky, Arkady]

Arlin,
It is too strong to state that Consumer should never send a message
equal in size to the size of immediate data.
Consumer knows from the context which one it is.
it may be based on dedicated connection, or based on ULP protocol
ordering.
Arkady 

Arkady Kanevsky                       email: arkady at netapp.com
Network Appliance Inc.               phone: 781-768-5395
1601 Trapelo Rd. - Suite 16.        Fax: 781-895-1195
Waltham, MA 02451                   central phone: 781-768-5300
 

> -----Original Message-----
> From: Kanevsky, Arkady 
> Sent: Monday, February 06, 2006 2:05 PM
> To: Davis, Arlin R; Sean Hefty
> Cc: dat-discussions at yahoogroups.com; openib-general at openib.org
> Subject: RE: [dat-discussions] [openib-general] [RFC] DAT 2.0 
> immediatedataproposal
> 
> Arlin,
> On Friday we agreed that receiver can not distinguish between 
> 4 byte of Send or 4 bytes of Immediate data if RDMA Write 
> with Immed is implemented as 2 operations:
> RDMA Write followed by Send.
> 
> ULP Reciever "expects" Immediate data that is why it posts 
> Recv. Depending on Transport capability it MAY complete as 
> Recv or as Recv_RDMA_Write_with_Immed_in_event.
> 
> Neither Provider not Consumer can distinguish between the 
> cases unless there is additional info.
> 
> Arkady
> 
> Arkady Kanevsky                       email: arkady at netapp.com
> Network Appliance Inc.               phone: 781-768-5395
> 1601 Trapelo Rd. - Suite 16.        Fax: 781-895-1195
> Waltham, MA 02451                   central phone: 781-768-5300
>  
> 
> > -----Original Message-----
> > From: Davis, Arlin R [mailto:arlin.r.davis at intel.com]
> > Sent: Monday, February 06, 2006 1:25 PM
> > To: Kanevsky, Arkady; Sean Hefty
> > Cc: dat-discussions at yahoogroups.com; openib-general at openib.org
> > Subject: RE: [dat-discussions] [openib-general] [RFC] DAT 2.0 
> > immediate dataproposal
> > 
> > 
> > Arkady,
> > 
> > Your requirements are slightly different then the proposed set of 
> > requirements.
> > 
> > "iii) DAPL Provider does not provide any identification 
> that that the 
> > Receive operation matches remote RDMA Write with Immediate 
> data if it 
> > completes as Receive DTO.
> > 
> > 	- It is up to an ULP to separate Receive completion of remote
> > Send from remote RDMA Write with 	  Immediate Data."
> > 
> > Tell me how this is possible? How can the application distinguish 
> > between a 4 byte message and a 4 byte immediate data 
> message? We would 
> > have to add a new requirement... "If the provider supports 
> immediate 
> > data in the payload the ULP cannot send a message equal to the 
> > immediate
> > data size".   
> > 
> > -arlin
> > 
> > >-----Original Message-----
> > >From: Kanevsky, Arkady [mailto:Arkady.Kanevsky at netapp.com]
> > >Sent: Monday, February 06, 2006 8:08 AM
> > >To: Sean Hefty; Davis, Arlin R
> > >Cc: dat-discussions at yahoogroups.com; openib-general at openib.org
> > >Subject: RE: [dat-discussions] [openib-general] [RFC] DAT
> > 2.0 immediate
> > dataproposal
> > >
> > >Here are the changes to the existing requirements chapters 
> for RDMA 
> > >Write with Immediate Data.
> > >
> > >Feedback please.
> > >Arkady
> > >
> > >Arkady Kanevsky                       email: arkady at netapp.com
> > >Network Appliance Inc.               phone: 781-768-5395
> > >1601 Trapelo Rd. - Suite 16.        Fax: 781-895-1195
> > >Waltham, MA 02451                   central phone: 781-768-5300
> > >
> > >
> > >> -----Original Message-----
> > >> From: Sean Hefty [mailto:mshefty at ichips.intel.com]
> > >> Sent: Friday, February 03, 2006 7:30 PM
> > >> To: Davis, Arlin R
> > >> Cc: dat-discussions at yahoogroups.com; openib-general at openib.org
> > >> Subject: Re: [dat-discussions] [openib-general] [RFC] DAT 2.0 
> > >> immediate dataproposal
> > >>
> > >> Davis, Arlin R wrote:
> > >> > "Applications need an optimized mechanism to notify the
> > >> receiving end
> > >> > that RDMA write data has completed beyond the two
> > operation method
> > >> > currently used (RDMA write followed by message send). 
> > This new RDMA
> > >> > write feature will support 4-bytes of inline data that
> > will be sent
> > >>
> > >> Is there any reason to restrict the size of the immediate data?  
> > >> Could you define the API such that the size is variable? 
>  I.e. the 
> > >> provider can simply give the immediate data size, with 0
> > indicating
> > >> that it is not supported.
> > >>
> > >> > It should avoid
> > >> > any latency penalties normally associated with a two
> > >> operation method.
> > >>
> > >> I would state this as a requirement.  A write followed by a send 
> > >> should be pushed to the application, since they may be able to 
> > >> provide additional optimizations (such as combining
> > >> operations) beyond what a provider could.
> > >>
> > >> > The initiating side must expose a 4-byte immediate data
> > >> parameter for
> > >> > the application to set the inline data. The receiving 
> side must 
> > >> > provide a mechanism to accept the 4-byte immediate 
> data. On the 
> > >> > receiving side, the write with immediate completion
> > notification is
> > >> > indicated through a receive completion. It is the
> > responsibility of
> > >> > the provider to identify to the application 4-byte
> > >> immediate data from
> > >> > a normal 4-byte send message. The inline byte ordering is
> > >> application specific."
> > >>
> > >> Requirements look good to me.
> > >>
> > >> - Sean
> > >> _______________________________________________
> > >> openib-general mailing list
> > >> openib-general at openib.org
> > >> http://openib.org/mailman/listinfo/openib-general
> > >>
> > >> To unsubscribe, please visit
> > >> http://openib.org/mailman/listinfo/openib-general
> > >>
> > 
> _______________________________________________
> openib-general mailing list
> openib-general at openib.org
> http://openib.org/mailman/listinfo/openib-general
> 
> To unsubscribe, please visit 
> http://openib.org/mailman/listinfo/openib-general
>