RE: [Intel-wired-lan] [PATCH net-next 1/9] e1000: switch to napi_consume_skb()

[Brelinski, Tony]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of
> Alexander Lobakin
> Sent: Tuesday, November 23, 2021 9:19 AM
> To: intel-wired-lan@xxxxxxxxxxxxxxxx
> Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Jakub Kicinski
> <kuba@xxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>
> Subject: [Intel-wired-lan] [PATCH net-next 1/9] e1000: switch to
> napi_consume_skb()
> 
> In order to take the best from per-cpu NAPI skbuff_head caches and CPU
> cycles, let's switch from dev_kfree_skb_any(), which passes skb back to the
> mm layer, to napi_consume_skb(), which feeds those caches on non-zero
> budget instead (falls back to the former on 0).
> Do the replacement in e1000_unmap_and_free_tx_resource(). There are
> 4 call sites of this function throughout the driver:
>  * e1000_clean_tx_ring(). Slowpath, process context, cleans the
>    whole Tx ring on ifdown. Use budget of 0 here;
>  * e1000_tx_map(). Hotpath, net Tx softirq, unmaps the buffers in
>    case of error. Use 0 as well;
>  * e1000_clean_tx_irq(). Hotpath, NAPI Tx completion polling cycle.
>    As the driver doesn't count completed Tx entries towards the NAPI
>    budget, just use the poll budget of 64 to utilize caches.
> 
> Apart from being a preparation for switching to napi_build_skb(), this is
> useful on its own as well, as napi_consume_skb() flushes skb caches by
> batches of 32 instead of one-at-a-time.
> 
> Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/e1000/e1000_main.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

Tested-by: Tony Brelinski <tony.brelinski@xxxxxxxxx>