[PATCH net-next] eth: bnxt: disable rx-copybreak by default

[PATCH net-next] eth: bnxt: disable rx-copybreak by default

[Jakub Kicinski]

rx-copybreak requires an extra slab allocation. Since bnxt uses
page pool frags and HDS by default, the rx-copybreak doesn't
buy us anything. The extra pressure on slab causes overload
on pre-sheaves kernels on modern AMD platforms.

In synthetic testing on net-next this patch shows little difference
but I think copybreak is "obvious waste" at this point.

Default rx-copybreak threshold to 0 / disabled.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 61c847b36b9f..044084af2254 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -36,7 +36,7 @@
 #include <linux/firmware/broadcom/tee_bnxt_fw.h>
 #endif
 
-#define BNXT_DEFAULT_RX_COPYBREAK 256
+#define BNXT_DEFAULT_RX_COPYBREAK 0
 #define BNXT_MAX_RX_COPYBREAK 1024
 
 extern struct list_head bnxt_block_cb_list;
-- 
2.54.0

Re: [PATCH net-next] eth: bnxt: disable rx-copybreak by default

[Pavan Chebbi]

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On Sat, May 30, 2026 at 2:25 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> rx-copybreak requires an extra slab allocation. Since bnxt uses
> page pool frags and HDS by default, the rx-copybreak doesn't
> buy us anything. The extra pressure on slab causes overload
> on pre-sheaves kernels on modern AMD platforms.
>
> In synthetic testing on net-next this patch shows little difference
> but I think copybreak is "obvious waste" at this point.
>
> Default rx-copybreak threshold to 0 / disabled.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  drivers/net/ethernet/broadcom/bnxt/bnxt.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Fine by me. We can always use set-tunable.
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>

> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> index 61c847b36b9f..044084af2254 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> @@ -36,7 +36,7 @@
>  #include <linux/firmware/broadcom/tee_bnxt_fw.h>
>  #endif
>
> -#define BNXT_DEFAULT_RX_COPYBREAK 256
> +#define BNXT_DEFAULT_RX_COPYBREAK 0
>  #define BNXT_MAX_RX_COPYBREAK 1024
>
>  extern struct list_head bnxt_block_cb_list;
> --
> 2.54.0
>

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