Messages in this thread |  | | Date | Sat, 6 Aug 2022 03:55:18 +0800 | From | Chao Gao <> | Subject | Re: [RFC v2 0/2] swiotlb performance optimizations |
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Ping. Intel reviewers, comments and suggestions are welcome.
On Mon, Jul 18, 2022 at 09:28:16AM +0800, Chao Gao wrote: >Intent of this post: > Seek reviews from Intel reviewers and anyone else in the list > interested in IO performance in confidential VMs. Need some acked-by > reviewed-by tags before I can add swiotlb maintainers to "to/cc" lists > and ask for a review from them. > >Changes from v1 to v2: >- rebase to the latest dma-mapping tree. >- drop the duplicate patch for mitigating lock contention >- re-collect perf data > >swiotlb is now widely used by confidential VMs. This series optimizes >swiotlb to reduce cache misses and lock contention during bounce buffer >allocation/free and memory bouncing to improve IO workload performance in >confidential VMs. > >Here are some FIO tests we did to demonstrate the improvement. > >Test setup >---------- > >A normal VM with 8vCPU and 32G memory, swiotlb is enabled by swiotlb=force. >FIO block size is 4K and iodepth is 256. Note that a normal VM is used so >that others lack of necessary hardware to host confidential VMs can reproduce >results below. > >Results >------- > >1 FIO job read/write IOPS (k) >vanilla read 216 > write 251 >optimized read 250 > write 270 > >1-job FIO sequential read/write perf increase by 19% and 8% respectively. > >Chao Gao (2): > swiotlb: use bitmap to track free slots > swiotlb: Allocate memory in a cache-friendly way > > include/linux/swiotlb.h | 8 ++- > kernel/dma/swiotlb.c | 127 +++++++++++++++++----------------------- > 2 files changed, 60 insertions(+), 75 deletions(-) > >-- >2.25.1 >
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