On Tue, 22 Nov 2016, Matthew Auld wrote: > On 9 November 2016 at 18:36, Hugh Dickins <hughd@xxxxxxxxxx> wrote: > > On Wed, 9 Nov 2016, Daniel Vetter wrote: > >> > >> Hi all -mm folks! > >> > >> Any feedback on these two? It's kinda an intermediate step towards a > >> full-blown gemfs, and I think useful for that. Or do we need to go > >> directly to our own backing storage thing? Aside from ack/nack from -mm I > >> think this is ready for merging. > > > > I'm currently considering them at last: will report back later. > > > > Full-blown gemfs does not come in here, of course; but let me > > fire a warning shot since you mention it: if it's going to use swap, > > then we shall probably have to nak it in favour of continuing to use > > infrastructure from mm/shmem.c. I very much understand why you would > > love to avoid that dependence, but I doubt it can be safely bypassed. > > Could you please elaborate on what specifically you don't like about > gemfs implementing swap, just to make sure I'm following? If we're talking about swap as implemented in mm/swapfile.c, and managed for tmpfs mainly through shmem_getpage_gfp(): that's slippery stuff, private to mm, and I would not want such trickiness duplicated somewhere down in drivers/gpu/drm, where mm developers and drm developers will keep on forgetting to keep it working correctly. But you write of gemfs "implementing" swap (and I see Daniel wrote of "our own backing storage"): perhaps you intend a disk or slow-mem file of your own, dedicated to paging gemfs objects according to your own rules, poked from memory reclaim via a shrinker. I certainly don't have the same quick objection to that: it may be a good way forward, though I'm not at all sure (and would prefer a name distinct from swap, so we wouldn't get confused - maybe gemswap). Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>