Re: [RFC 0/8] Copy Offload with Peer-to-Peer PCI Memory

Knut Omang
2017-04-25T06:30:03Z

On Mon, 2017-04-24 at 10:14 -0600, Logan Gunthorpe wrote:
>
> On 24/04/17 01:36 AM, Knut Omang wrote:
> > My first reflex when reading this thread was to think that this whole domain
> > lends it self excellently to testing via Qemu. Could it be that doing this in
> > the opposite direction might be a safer approach in the long run even though
> > (significant) more work up-front?
>
> That's an interesting idea. We did do some very limited testing on qemu
> with one iteration of our work. However, it's difficult because there is
> no support for any RDMA devices which are a part of our primary use
> case.

Yes, that's why I used 'significant'. One good thing is that given resources
it can easily be done in parallel with other development, and will give additional
insight of some form.

> I also imagine it would be quite difficult to develop those models
> given the array of hardware that needs to be supported and the deep
> functional knowledge required to figure out appropriate restrictions.

From my naive perspective it seems it need not even be a full model to get some benefits,
just low level functionality tests with some instances of a
device that offers some MMIO space 'playground'.

Or maybe you can leverage some of the already implemented emulated devices in Qemu?

Knut

>
> Logan
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