On 5/13/24 6:09 AM, Anuj gupta wrote: > 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. Yes, please just send a separate series/patch for both liburing and fio. This series should be strictly the kernel side changes required, then reference/link the postings for the t/io_uring and liburing test case(s) in the cover letter. -- Jens Axboe
