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

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Message-ID: <918dbc66-b8ed-4b38-b147-f271137c716a@huawei.com>
Date: Tue, 23 Dec 2025 11:14:15 +0800
From: Qinxin Xia <xiaqinxin@...wei.com>
To: Barry Song <21cnbao@...il.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 2025/12/23 05:10:04, Barry Song <21cnbao@...il.com> wrote:
> 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

Agreed. I'll fix the print format in the next version.

-- 
Thanks,
Qinxin