When doing manual injection of the frame, it is required to check if the
TX FIFO is ready to accept the next word of the frame. For this we are
using 'readx_poll_timeout_atomic', the only problem is that before it
actually checks the status, is determining the time when to finish polling
the status. Which seems to be an expensive operation.
Therefore check the status of the TX FIFO before calling
'readx_poll_timeout_atomic'.
Doing this will improve the TX bitrate by ~70%. Because 99% the FIFO is
ready by that time. The measurements were done using iperf3.
Before:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.03 sec 55.2 MBytes 46.2 Mbits/sec 0 sender
[ 5] 0.00-10.04 sec 53.8 MBytes 45.0 Mbits/sec receiver
After:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.10 sec 95.0 MBytes 78.9 Mbits/sec 0 sender
[ 5] 0.00-10.11 sec 95.0 MBytes 78.8 Mbits/sec receiver
Signed-off-by: Horatiu Vultur <[email protected]>
---
v1->v2
- check for TX FIFO status before calling readx_poll_timeout_atomic
---
drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index 81c01665d01e..e1bcb28039dc 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -185,6 +185,9 @@ static int lan966x_port_inj_ready(struct lan966x *lan966x, u8 grp)
{
u32 val;
+ if (lan_rd(lan966x, QS_INJ_STATUS) & QS_INJ_STATUS_FIFO_RDY_SET(BIT(grp)))
+ return 0;
+
return readx_poll_timeout_atomic(lan966x_port_inj_status, lan966x, val,
QS_INJ_STATUS_FIFO_RDY_GET(val) & BIT(grp),
READL_SLEEP_US, READL_TIMEOUT_US);
--
2.33.0
On Thu, Mar 10, 2022 at 09:40:05AM +0100, Horatiu Vultur wrote:
> When doing manual injection of the frame, it is required to check if the
> TX FIFO is ready to accept the next word of the frame. For this we are
> using 'readx_poll_timeout_atomic', the only problem is that before it
> actually checks the status, is determining the time when to finish polling
> the status. Which seems to be an expensive operation.
> Therefore check the status of the TX FIFO before calling
> 'readx_poll_timeout_atomic'.
> Doing this will improve the TX bitrate by ~70%. Because 99% the FIFO is
> ready by that time. The measurements were done using iperf3.
>
> Before:
> [ ID] Interval Transfer Bitrate Retr
> [ 5] 0.00-10.03 sec 55.2 MBytes 46.2 Mbits/sec 0 sender
> [ 5] 0.00-10.04 sec 53.8 MBytes 45.0 Mbits/sec receiver
>
> After:
> [ ID] Interval Transfer Bitrate Retr
> [ 5] 0.00-10.10 sec 95.0 MBytes 78.9 Mbits/sec 0 sender
> [ 5] 0.00-10.11 sec 95.0 MBytes 78.8 Mbits/sec receiver
>
> Signed-off-by: Horatiu Vultur <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Andrew
Hello:
This patch was applied to netdev/net-next.git (master)
by David S. Miller <[email protected]>:
On Thu, 10 Mar 2022 09:40:05 +0100 you wrote:
> When doing manual injection of the frame, it is required to check if the
> TX FIFO is ready to accept the next word of the frame. For this we are
> using 'readx_poll_timeout_atomic', the only problem is that before it
> actually checks the status, is determining the time when to finish polling
> the status. Which seems to be an expensive operation.
> Therefore check the status of the TX FIFO before calling
> 'readx_poll_timeout_atomic'.
> Doing this will improve the TX bitrate by ~70%. Because 99% the FIFO is
> ready by that time. The measurements were done using iperf3.
>
> [...]
Here is the summary with links:
- [net-next,v2] net: lan966x: Improve the CPU TX bitrate.
https://git.kernel.org/netdev/net-next/c/fb9eb027fbc9
You are awesome, thank you!
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