On Mon, May 13, 2024 at 1:59 PM Chenliang Li <cliang01.li@xxxxxxxxxxx> wrote: > > Registered buffers are stored and processed in the form of bvec array, > each bvec element typically points to a PAGE_SIZE page but can also work > with hugepages. Specifically, a buffer consisting of a hugepage is > coalesced to use only one hugepage bvec entry during registration. > This coalescing feature helps to save both the space and DMA-mapping time. > > However, currently the coalescing feature doesn't work for multi-hugepage > buffers. For a buffer with several 2M hugepages, we still split it into > thousands of 4K page bvec entries while in fact, we can just use a > handful of hugepage bvecs. > > This patch series enables coalescing registered buffers with more than > one hugepages. It optimizes the DMA-mapping time and saves memory for > these kind of buffers. > > Perf diff of 8M(4*2M) hugepage fixed buffer fio test: > > fio/t/io_uring -d64 -s32 -c32 -b8388608 -p0 -B1 -F0 -n1 -O1 -r10 \ > -R1 /dev/nvme0n1 It seems you modified t/io_uring to allocate from hugepages. It would be nice to mention that part here. -- Anuj Gupta
