Re: [PATCH net-next] sfc: reduce the number of requested xdp ev queues

[Martin Habets]

On Wed, Jan 20, 2021 at 01:27:59PM -0800, Ivan Babrou wrote:
> Without this change the driver tries to allocate too many queues,
> breaching the number of available msi-x interrupts on machines
> with many logical cpus and default adapter settings:
> 
> Insufficient resources for 12 XDP event queues (24 other channels, max 32)
> 
> Which in turn triggers EINVAL on XDP processing:
> 
> sfc 0000:86:00.0 ext0: XDP TX failed (-22)
> 
> Signed-off-by: Ivan Babrou <ivan@xxxxxxxxxxxxxx>

Acked-by: Martin Habets <habetsm.xilinx@xxxxxxxxx>

> ---
>  drivers/net/ethernet/sfc/efx_channels.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c
> index a4a626e9cd9a..1bfeee283ea9 100644
> --- a/drivers/net/ethernet/sfc/efx_channels.c
> +++ b/drivers/net/ethernet/sfc/efx_channels.c
> @@ -17,6 +17,7 @@
>  #include "rx_common.h"
>  #include "nic.h"
>  #include "sriov.h"
> +#include "workarounds.h"
>  
>  /* This is the first interrupt mode to try out of:
>   * 0 => MSI-X
> @@ -137,6 +138,7 @@ static int efx_allocate_msix_channels(struct efx_nic *efx,
>  {
>  	unsigned int n_channels = parallelism;
>  	int vec_count;
> +	int tx_per_ev;
>  	int n_xdp_tx;
>  	int n_xdp_ev;
>  
> @@ -149,9 +151,9 @@ static int efx_allocate_msix_channels(struct efx_nic *efx,
>  	 * multiple tx queues, assuming tx and ev queues are both
>  	 * maximum size.
>  	 */
> -
> +	tx_per_ev = EFX_MAX_EVQ_SIZE / EFX_TXQ_MAX_ENT(efx);
>  	n_xdp_tx = num_possible_cpus();
> -	n_xdp_ev = DIV_ROUND_UP(n_xdp_tx, EFX_MAX_TXQ_PER_CHANNEL);
> +	n_xdp_ev = DIV_ROUND_UP(n_xdp_tx, tx_per_ev);
>  
>  	vec_count = pci_msix_vec_count(efx->pci_dev);
>  	if (vec_count < 0)
> -- 
> 2.29.2