2024-04-15 09:49:51

by Paul Barker

Subject: [net-next RFC v3 5/7] net: ravb: Enable SW IRQ Coalescing for GbEth

Software IRQ Coalescing is required to improve network stack performance
in the RZ/G2L SoC family and the RZ/G3S SoC, i.e. the SoCs which use the
GbEth IP.

This patch gives the following improvements during testing with iperf3:

* RZ/G2L:
* TCP RX: same bandwidth with -6% CPU load (76% -> 71%)
* UDP RX: same bandwidth with -10% CPU load (99% -> 89%)

* RZ/G2UL:
* UDP RX: +4200% bandwidth (1.23Mbps -> 53Mbps)

* RZ/G3S:
* UDP RX: +425% bandwidth (1.23Mbps -> 6.46Mbps)

The improvement of UDP RX bandwidth for the single core SoCs (RZ/G2UL &
RZ/G3S) is particularly critical.

Signed-off-by: Paul Barker <[email protected]>
---
drivers/net/ethernet/renesas/ravb.h | 1 +
drivers/net/ethernet/renesas/ravb_main.c | 4 ++++
2 files changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 71de2a7aa27c..9c6392ade2f1 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -1054,6 +1054,7 @@ struct ravb_hw_info {
u32 rx_max_desc_use;
u32 rx_desc_size;
unsigned aligned_tx: 1;
+ unsigned needs_irq_coalesce:1; /* Needs software IRQ coalescing */

/* hardware features */
unsigned internal_delay:1; /* AVB-DMAC has internal delays */
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 12618171f6d5..26b70b996bd3 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2663,6 +2663,7 @@ static const struct ravb_hw_info gbeth_hw_info = {
.tx_counters = 1,
.carrier_counters = 1,
.half_duplex = 1,
+ .needs_irq_coalesce = 1,
};

static const struct of_device_id ravb_match_table[] = {
@@ -2937,6 +2938,9 @@ static int ravb_probe(struct platform_device *pdev)
if (info->nc_queues)
netif_napi_add(ndev, &priv->napi[RAVB_NC], ravb_poll);

+ if (info->needs_irq_coalesce)
+ netdev_sw_irq_coalesce_default_on(ndev);
+
/* Network device register */
error = register_netdev(ndev);
if (error)
--
2.39.2

2024-04-19 20:26:28

by Sergey Shtylyov

Subject: Re: [net-next RFC v3 5/7] net: ravb: Enable SW IRQ Coalescing for GbEth

On 4/15/24 12:48 PM, Paul Barker wrote:

> Software IRQ Coalescing is required to improve network stack performance
> in the RZ/G2L SoC family and the RZ/G3S SoC, i.e. the SoCs which use the
> GbEth IP.
>
> This patch gives the following improvements during testing with iperf3:
>
> * RZ/G2L:
> * TCP RX: same bandwidth with -6% CPU load (76% -> 71%)
> * UDP RX: same bandwidth with -10% CPU load (99% -> 89%)
>
> * RZ/G2UL:
> * UDP RX: +4200% bandwidth (1.23Mbps -> 53Mbps)
>
> * RZ/G3S:
> * UDP RX: +425% bandwidth (1.23Mbps -> 6.46Mbps)
>
> The improvement of UDP RX bandwidth for the single core SoCs (RZ/G2UL &
> RZ/G3S) is particularly critical.
>
> Signed-off-by: Paul Barker <[email protected]>

Reviewed-by: Sergey Shtylyov <[email protected]>

[...]

> diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> index 71de2a7aa27c..9c6392ade2f1 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -1054,6 +1054,7 @@ struct ravb_hw_info {
> u32 rx_max_desc_use;
> u32 rx_desc_size;
> unsigned aligned_tx: 1;
> + unsigned needs_irq_coalesce:1; /* Needs software IRQ coalescing */

Perhaps something shorter, like coalesce_irqs?

[...]

MBR, Sergey