Re: [PATCH v6 3/3] tools/dma: Add dma_map_sg support

[Barry Song]

On Mon, Jan 12, 2026 at 5:34 PM Qinxin Xia <xiaqinxin@xxxxxxxxxx> wrote:
>
> Support for dma_map_sg, add option '-m' to distinguish mode.
>
> i) Users can set option '-m' to select mode:
>    DMA_MAP_BENCH_SINGLE_MODE=0, DMA_MAP_BENCH_SG_MODE:=1
>    (The mode is also show in the test result).
> ii) Users can set option '-g' to set sg_nents
>     (total count of entries in scatterlist)
>     the maximum number is 1024. Each of sg buf size is PAGE_SIZE.
>     e.g
>     [root@localhost]# ./dma_map_benchmark -m 1 -g 8 -t 8 -s 30 -d 2
>     dma mapping mode: DMA_MAP_BENCH_SG_MODE
>     dma mapping benchmark: threads:8 seconds:30 node:-1
>     dir:FROM_DEVICE granule/sg_nents: 8
>     average map latency(us):1.4 standard deviation:0.3
>     average unmap latency(us):1.3 standard deviation:0.3
>     [root@localhost]# ./dma_map_benchmark -m 0 -g 8 -t 8 -s 30 -d 2
>     dma mapping mode: DMA_MAP_BENCH_SINGLE_MODE
>     dma mapping benchmark: threads:8 seconds:30 node:-1
>     dir:FROM_DEVICE granule/sg_nents: 8
>     average map latency(us):1.0 standard deviation:0.3
>     average unmap latency(us):1.3 standard deviation:0.5
>

What happens if m is set to 0 while g is set to 8?

Thanks
Barry