Re: [PATCH v2] app/dma-perf: fix physical address seg-fault

[Jerin Jacob <jerinjacobk@gmail.com>]

On Wed, Aug 16, 2023 at 3:21 PM Vipin Varghese <vipin.varghese@amd.com> wrote:
>
> do_cpu_mem_copy uses DPDK API rte_mbuf_data_iova to return
> the start of the virtual address for both src and dst.
> But in case of iova mode set as PA, this results in seg-fault.
> This is because rte_memcpy uses VA address and not PA.
>
> This fix invokes `rte_pktmbuf_mtod` for both src and dst.
>
> Bugzilla ID: 1269
> Fixes: 623dc9364dc6 ("app/dma-perf: introduce DMA performance test")
> Cc: cheng1.jiang@intel.com
>
> Cc: stable@dpdk.org
>
> Signed-off-by: Vipin Varghese <vipin.varghese@amd.com>
> Suggested-by: Anoob Joseph <anoobj@marvell.com>
> ---
>
> v2:
>  - suggest use of pktmbuf_mtod for both va and pa.
>
> tested for both va and pa
>
> CMD:
> PA: dpdk-test-dma-perf --iova-mode=pa  -- --config test.ini
> VA: dpdk-test-dma-perf --iova-mode=va  -- --config test.ini
> DC: dpdk-test-dma-perf --iova-mode=dc  -- --config test.ini
>
> Log: fails for dc mode `EAL: invalid parameters for --iova-mode`
>
> test.ini:
> ```
> [case1]
> type=CPU_MEM_COPY
> mem_size=10
> buf_size=64,8192,2,MUL
> src_numa_node=0
> dst_numa_node=0
> cache_flush=0
> test_seconds=2
> lcore = 7
> eal_args=--in-memory --no-pci
> ```
> ---
>  app/test-dma-perf/benchmark.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/app/test-dma-perf/benchmark.c b/app/test-dma-perf/benchmark.c
> index 0601e0d171..1d1c9bde99 100644
> --- a/app/test-dma-perf/benchmark.c
> +++ b/app/test-dma-perf/benchmark.c
> @@ -288,10 +288,11 @@ do_cpu_mem_copy(void *p)
>
>         while (1) {
>                 for (i = 0; i < nr_buf; i++) {
> +                       void *src = rte_pktmbuf_mtod(dsts[i], void *);
> +                       void *dst = rte_pktmbuf_mtod(srcs[i], void *);

Use _const_ in fast path if src and dst in not changing as better
optimization hint to compiler.