linux-kernel - Re: [PATCH v5 3/3] tools/dma: Add dma_map

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Message-ID: <CAGsJ_4yyFXmeHKwb4E7PA9ndOrB79aQKAEKSTmJEVPO1OtiqnA@mail.gmail.com>
Date: Tue, 23 Dec 2025 10:10:04 +1300
From: Barry Song <21cnbao@...il.com>
To: Qinxin Xia <xiaqinxin@...wei.com>
Cc: jonathan.cameron@...wei.com, wangzhou1@...ilicon.com, 
	iommu@...ts.linux.dev, prime.zeng@...wei.com, fanghao11@...wei.com, 
	linux-kernel@...r.kernel.org, linuxarm@...wei.com
Subject: Re: [PATCH v5 3/3] tools/dma: Add dma_map_sg support

On Tue, Dec 23, 2025 at 4:33 AM Qinxin Xia <xiaqinxin@...wei.com> 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@...alhost]# ./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@...alhost]# ./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
>
> Reviewed-by: Barry Song <baohua@...nel.org>
> Signed-off-by: Qinxin Xia <xiaqinxin@...wei.com>
> ---
>  tools/dma/dma_map_benchmark.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/tools/dma/dma_map_benchmark.c b/tools/dma/dma_map_benchmark.c
> index dd0ed528e6df..39102330a43f 100644
> --- a/tools/dma/dma_map_benchmark.c
> +++ b/tools/dma/dma_map_benchmark.c
> @@ -26,6 +26,8 @@ int main(int argc, char **argv)
>         int fd, opt;
>         /* default single thread, run 20 seconds on NUMA_NO_NODE */
>         int threads = 1, seconds = 20, node = -1;
> +       /* default single map mode */
> +       int map_mode = DMA_MAP_BENCH_SINGLE_MODE;
>         /* default dma mask 32bit, bidirectional DMA */
>         int bits = 32, xdelay = 0, dir = DMA_MAP_BIDIRECTIONAL;
>         /* default granule 1 PAGESIZE */
> @@ -33,7 +35,7 @@ int main(int argc, char **argv)
>
>         int cmd = DMA_MAP_BENCHMARK;
>
> -       while ((opt = getopt(argc, argv, "t:s:n:b:d:x:g:")) != -1) {
> +       while ((opt = getopt(argc, argv, "t:s:n:b:d:x:g:m:")) != -1) {
>                 switch (opt) {
>                 case 't':
>                         threads = atoi(optarg);
> @@ -56,11 +58,20 @@ int main(int argc, char **argv)
>                 case 'g':
>                         granule = atoi(optarg);
>                         break;
> +               case 'm':
> +                       map_mode = atoi(optarg);
> +                       break;
>                 default:
>                         return -1;
>                 }
>         }
>
> +       if (map_mode < 0 || map_mode >= DMA_MAP_BENCH_MODE_MAX) {
> +               fprintf(stderr, "invalid map mode, SINGLE_MODE:%d, SG_MODE: %d\n",
> +                       DMA_MAP_BENCH_SINGLE_MODE, DMA_MAP_BENCH_SG_MODE);
> +               exit(1);
> +       }
> +
>         if (threads <= 0 || threads > DMA_MAP_MAX_THREADS) {
>                 fprintf(stderr, "invalid number of threads, must be in 1-%d\n",
>                         DMA_MAP_MAX_THREADS);
> @@ -110,13 +121,15 @@ int main(int argc, char **argv)
>         map.dma_dir = dir;
>         map.dma_trans_ns = xdelay;
>         map.granule = granule;
> +       map.map_mode = map_mode;
>
>         if (ioctl(fd, cmd, &map)) {
>                 perror("ioctl");
>                 exit(1);
>         }
>
> -       printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule: %d\n",
> +       printf("dma mapping mode: %d\n", map_mode);
> +       printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule/sg_nents: %d\n",

Why can’t we print mode on this line,
and why isn’t the integer converted to a string
like directions?

Thanks
Barry