[rds-devel] Re: RDS/RDMA protocol
Richard Frank
richard.frank at oracle.com
Tue Nov 6 07:01:17 PST 2007
Or Gerlitz wrote:
> Richard Frank wrote:
>> Zach Brown wrote:
>
>>> You should be sending these mails to rds-devel. There's a great chance
>>> that you'll want the people actively involved in RDS to respond.
>
>> Yes - we're getting hammered about not using rds-dev - let's try and
>> move all our RDS discussion - that does not contain Oracle private
>> information - into rds-dev.
>
> I did not CC rds-devel by mistake, sorry.
>
>> The message send is a compound operation - it includes a regular RDS
>> send (the immediate data) and the RDMA data.
>>
>> The rdma operation is pushed down the wire and then the immediate
>> data is pipelined right behind the RDMA.
>>
>> Keep in mind when the client requested the rdma - it sent along an
>> identifier for the operation. When the rdma server responds - it
>> encodes the client provided identifier in the immediate data
>> response message.
>>
>> So when the client recv's the immediate data message (response to
>> request) - it gets back the id of the request which completed and it
>> knows the rdma is complete due to ordering of the RC that both ops
>> traveled over.
>
> Just to make sure I understand, the "immediate data message" you
> mention here is at the app level, not RDS level, correct? for example
> when you say "it encodes the client provided identifier" etc its left
> to the app how to encode this?
>
> Or.
>
Yes, the app is sending the immediate data - along with the rdma
operation via the single RDS send operation.
The immediate data send and rdma are an atomic operation - either both
succeed or neither does.
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