Hi, On Thu, 10 Jun 2021 at 20:02, Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> wrote: > > Hi, Matthew! > > I got a funny result from the hugepages selftest when trying to break > out some functionality from shmem to make a ttm page pool for > cached-only TTM system bos. > > It turns out that shmem computed the pagesizes using the underlying > pages rather than the dma segments, so when I changed that, hugepages > started failing. > > https://patchwork.freedesktop.org/series/91227/ > > But when hacking the page-size computation to use the underlying pages, > it's fine again > > https://patchwork.freedesktop.org/series/91336/ > > It seems like some assumption about huge dma segments is wrong, either > in our page-size calculation, in the selftest or in the actual huge page > setup. Could it be that huge sized segments are assumed to be properly > aligned? We disabled THP for $reasons, so shrink_thp will pretty much always skip I think, unless we happen to coalesce enough pages to make a 2M page. I guess with your change that is somehow more likely now that we use i915_sg_dma_sizes() and call it after we do the dma_map_sg. I think the intel iommu driver also does coalescing or something. The sg_page_sizes is mostly just a heuristic though. The test failure looks like a bug in the test though, I think since the object might still be active(gpu_write) we need to also force SHRINK_ACTIVE, otherwise the shrinker will just ignore the object. The test did work at some point but I guess has been modified/refactored a few times. We can either fix the test, or just delete it(igt_shrink_thp). > > /Thomas > > > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
