On Wed, Aug 13, 2014 at 6:38 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: >> Yes, it currently limits you to half of memory, but at least we would >> like to make it tuneable since there are a lot of user cases where the >> user wants to use 90% of memory for GPU tasks at the expense of >> everything else. > > Ime a lot of fun stuff starts to happen when you go there. We have piles > of memory thrashing testcases and generally had lots of fun with our > shrinker, so I think until you've really beaten onto those paths in > ttm+radeon I'd keep the limit where it is. One example that already starts if you go above 50% is that by default the dirty pagecache is limited to 40% of memory. Above that you start to stall in writeback, but gpus are really fast at re-dirtying memory. So we've seen cases where the core mm OOMed with essentially 90% of memory on writeback and piles of free swap. Waiting a few seconds for the SSD to catch up would have gotten it out of that tight spot without killing any process. One side-effect of such fun is that memory allocations start to fail in really interesting places, and you need to pile in hacks so make it all a bit more synchronous to avoid the core mm freaking out. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
