In current ping-pong design, xdp_hw_metadata will wait until the packet
transmition completely done, then only start to receive the next packet.

The current sleep interval is 10ms, which is unnecessary large. Typically,
a NIC does not need such a long time to transmit a packet. Furthermore,
during this 10ms sleep time, the app is unable to receive incoming packets.

Therefore, this commit reduce sleep interval to 10us, so that
xdp_hw_metadata able to support periodic packets with shorter interval.
10us * 500 = 5ms should be enough for packet transmission and status
retrival.

Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
---
 tools/testing/selftests/bpf/xdp_hw_metadata.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
index 878d68db0325..bdf5d8180067 100644
--- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
@@ -480,7 +480,7 @@ static int verify_metadata(struct xsk *rx_xsk, int rxq, int server_fd, clockid_t
 					for (int j = 0; j < 500; j++) {
 						if (complete_tx(xsk, clock_id))
 							break;
-						usleep(10*1000);
+						usleep(10);
 					}
 				}
 			}
-- 
2.34.1

On 03/02, Song Yoong Siang wrote:
> In current ping-pong design, xdp_hw_metadata will wait until the packet
> transmition completely done, then only start to receive the next packet.
> 
> The current sleep interval is 10ms, which is unnecessary large. Typically,
> a NIC does not need such a long time to transmit a packet. Furthermore,
> during this 10ms sleep time, the app is unable to receive incoming packets.
> 
> Therefore, this commit reduce sleep interval to 10us, so that
> xdp_hw_metadata able to support periodic packets with shorter interval.
> 10us * 500 = 5ms should be enough for packet transmission and status
> retrival.
> 
> Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>

Acked-by: Stanislav Fomichev <sdf@google.com>

Song Yoong Siang wrote:
> In current ping-pong design, xdp_hw_metadata will wait until the packet
> transmition completely done, then only start to receive the next packet.
> 
> The current sleep interval is 10ms, which is unnecessary large. Typically,
> a NIC does not need such a long time to transmit a packet. Furthermore,
> during this 10ms sleep time, the app is unable to receive incoming packets.
> 
> Therefore, this commit reduce sleep interval to 10us, so that
> xdp_hw_metadata able to support periodic packets with shorter interval.
> 10us * 500 = 5ms should be enough for packet transmission and status
> retrival.
> 
> Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
> ---
>  tools/testing/selftests/bpf/xdp_hw_metadata.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> index 878d68db0325..bdf5d8180067 100644
> --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> @@ -480,7 +480,7 @@ static int verify_metadata(struct xsk *rx_xsk, int rxq, int server_fd, clockid_t
>  					for (int j = 0; j < 500; j++) {
>  						if (complete_tx(xsk, clock_id))
>  							break;
> -						usleep(10*1000);
> +						usleep(10);
>  					}
>  				}
>  			}
> -- 
> 2.34.1
> 

Acked-by: John Fastabend <john.fastabend@gmail.com>