Re: [Intel-gfx] [PATCH 03/25] dma-buf.rst: Document why idenfinite fences are a bad idea

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jul 09, 2020 at 08:36:43AM +0100, Daniel Stone wrote:
> Hi,
> 
> On Tue, 7 Jul 2020 at 21:13, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > Comes up every few years, gets somewhat tedious to discuss, let's
> > write this down once and for all.
> 
> Thanks for writing this up! I wonder if any of the notes from my reply
> to the previous-version thread would be helpful to more explicitly
> encode the carrot of dma-fence's positive guarantees, rather than just
> the stick of 'don't do this'. ;) Either way, this is:

I think the carrot should go into the intro section for dma-fence, this
section here is very much just the "don't do this" part. The previous
patches have an attempt at encoding this a bit, maybe see whether there's
a place for your reply (or parts of it) to fit?

> Acked-by: Daniel Stone <daniels@collabora.com>
> 
> > What I'm not sure about is whether the text should be more explicit in
> > flat out mandating the amdkfd eviction fences for long running compute
> > workloads or workloads where userspace fencing is allowed.
> 
> ... or whether we just say that you can never use dma-fence in
> conjunction with userptr.

Uh userptr is entirely different thing. That one is ok. It's userpsace
fences or gpu futexes or future fences or whatever we want to call them.
Or is there some other confusion here?.
-Daniel


> 
> Cheers,
> Daniel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch