[ofa-general] RDMA write completion question

[Michael Krause]

At 08:13 AM 5/24/2007, Tang, Changqing wrote:

>But I was learned a while back, that local rdma completion only means
>that
>the data has been received by remote HCA, and an ACK has been
>acknowledged,
>the remote HCA may have deliveried the data to host memory, may NOT.
>
>Is this still true ?

Yes.   Unless a RDMA Read is done to flush all prior operations to host 
memory, acknowledgement of a RDMA Write via the IB protocol only indicates 
the packet arrived with a valid CRC to the CA.  There is no guarantee of 
anything getting to host memory or that any data corruption has been 
prevented as a CRC only guarantees the packet traversed the fabric without 
a CRC detectable error occurring.

Mike


>--CQ
>
>
>
> > -----Original Message-----
> > From: general-bounces at lists.openfabrics.org
> > [mailto:general-bounces at lists.openfabrics.org] On Behalf Of
> > Devesh Sharma
> > Sent: Thursday, May 24, 2007 10:08 AM
> > To: Gleb Natapov
> > Cc: general at lists.openfabrics.org
> > Subject: Re: [ofa-general] RDMA write completion question
> >
> > On 5/24/07, Gleb Natapov <glebn at voltaire.com> wrote:
> > > Hi,
> > >
> > >  Does local RDMA write completion guaranties that a data that was
> > > RDMAed is already accessible in a destination's host _memory_?
> > Local RDMA write completion guarantees that the data you have
> > RDMAed has been copied into the remote buffer, without any
> > data corruption.
> > >
> > > --
> > >                        Gleb.
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