From: "Hefty, Sean" <sean.hefty@intel.com>
To: Terry Toole <toole@photodiagnostic.com>, Jason Gunthorpe <jgg@ziepe.ca>
Cc: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: RE: Is it possible to transfer a large file between two computers using RDMA UD?
Date: Thu, 2 Jan 2020 19:25:34 +0000 [thread overview]
Message-ID: <CY4PR11MB14302D923E9CFF0665E67B3F9E200@CY4PR11MB1430.namprd11.prod.outlook.com> (raw)
In-Reply-To: <CADw-U9BTH1-2FztrKnC=tTTH93wOZg3FM2qJgjneNz-6-kywiw@mail.gmail.com>
> > > Is it possible to transfer a large file, say 25GB, between two computers using
> > > RDMA UD, and have an exact copy of the original file on the receiving side? My
> > > understanding is that the order of the messages is not guaranteed with UD.
> > > But I thought that if I only use one QP I could ensure that the ordering of the
> > > data will be predictable.
> >
> > It is not guaranteed to be in order.
> >
> > Why would you do this anyhow? The overhead to use RC is pretty small
> >
> So even if I am using only 1 QP, it is still not guaranteed to be in
> order. Ok. Thanks.
The spec doesn't guarantee ordering, though I doubt messages would ever be unordered in practice. You could transfer a sequence number as immediate data to allow the receiver to verify (and correct) packet ordering, and detect lost packets.
- Sean
next prev parent reply other threads:[~2020-01-02 19:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-02 14:47 Is it possible to transfer a large file between two computers using RDMA UD? Terry Toole
2020-01-02 18:29 ` Jason Gunthorpe
2020-01-02 19:11 ` Terry Toole
2020-01-02 19:25 ` Hefty, Sean [this message]
2020-01-02 19:31 ` Jason Gunthorpe
2020-01-02 19:45 ` Terry Toole
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