Re: [RFC PATCH v2 0/2] add simple copy support

[Javier González]

On 08.12.2020 13:24, Johannes Thumshirn wrote:
> On 08/12/2020 14:13, Javier González wrote:
> > On 08.12.2020 12:37, Johannes Thumshirn wrote:
> > > On 08/12/2020 13:22, Javier González wrote:
> > > > Good idea. Are you thinking of a sysfs entry to select the backend?
> > >
> > > Not sure on this one, initially I thought of a sysfs file, but then
> > > how would you do it. One "global" sysfs entry is probably a bad idea.
> > > Having one per block device to select native vs emulation maybe? And
> > > a good way to benchmark.
> >
> > I was thinking a per block device to target the use case where a certain
> > implementation / workload is better one way or the other.
>
> Yes something along those lines.
>
> > > The other idea would be a benchmark loop on boot like the raid library
> > > does.
> > >
> > > Then on the other hand, there might be workloads that run faster with
> > > the emulation and some that run faster with the hardware acceleration.
> > >
> > > I think these points are the reason the last attempts got stuck.
> >
> > Yes. I believe that any benchmark we run would be biased in a certain
> > way. If we can move forward with a sysfs entry and default to legacy
> > path, we would not alter current behavior and enable NVMe copy offload
> > (for now) for those that want to use it. We can then build on top of it.
> >
> > Does this sound like a reasonable approach?
>
> Yes this sounds like a reasonable approach to me.

Cool. We will add this to the V3 then.

Thanks Johannes!