Re: [RFC] mm: gup: add helper page_try_gup_pin(page)

[Jan Kara]

On Sun 03-11-19 22:09:03, John Hubbard wrote:
> On 11/3/19 8:34 PM, Hillf Danton wrote:
> > future, we have options for instance that gupers periodically release
> > their references and re-pin pages after data sync the same way as the
> > current flusher does.
> > 
> 
> That's one idea. I don't see it as viable, given the behavior of, say,
> a compute process running OpenCL jobs on a GPU that is connected via
> a network or Infiniband card--the idea of "pause" really looks more like
> "tear down the complicated multi-driver connection, writeback, then set it
> all up again", I suspect. (And if we could easily interrupt the job, we'd
> probably really be running with a page-fault-capable GPU plus and IB card
> that does ODP, plus HMM, and we wouldn't need to gup-pin anyway...)
> 
> Anyway, this is not amenable to quick fixes, because the problem is
> a couple of missing design pieces. Which we're working on putting in.
> But meanwhile, smaller changes such as this one are just going to move
> the problems to different places, rather than solving them. So it's best
> not to do that.

Yeah, fully agreed here. Quick half baked fixes will make the current messy
situation even worse...

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR