Subject: Re: [PATCHv2 net] Documentation: add description for net.core.gro_normal_batch

From: Jakub Kicinski <[email-masked]>
Date: Tue, 17 May 2022 17:21:41 -0700

On Fri, 13 May 2022 11:02:35 -0400 Xin Long wrote:
> Describe it in admin-guide/sysctl/net.rst like other Network core options.
> Users need to know gro_normal_batch for performance tuning.
> 
> v1->v2:
>   - Improved the description according to the suggestion from Edward and
>     Jakub.
> 
> Fixes: 323ebb61e32b ("net: use listified RX for handling GRO_NORMAL skbs")
> Reported-by: Prijesh Patel <[email-masked]>
> Signed-off-by: Xin Long <[email-masked]>
> ---
>  Documentation/admin-guide/sysctl/net.rst | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
> index f86b5e1623c6..5cb99403bf03 100644
> --- a/Documentation/admin-guide/sysctl/net.rst
> +++ b/Documentation/admin-guide/sysctl/net.rst
> @@ -374,6 +374,17 @@ option is set to SOCK_TXREHASH_DEFAULT (i. e. not overridden by setsockopt).
>  If set to 1 (default), hash rethink is performed on listening socket.
>  If set to 0, hash rethink is not performed.
>  
> +gro_normal_batch
> +----------------
> +
> +Maximum number of the segments to batch up for GRO list-RX.

How about s/for GRO list-RX/on output of GRO/ ?

> When a packet exits
> +GRO, either as a coalesced superframe or as an original packet which GRO has
> +decided not to coalesce, it is placed on a per-NAPI list. This list is then
> +passed to the stack when the segments in this list count towards the
> +gro_normal_batch limit.

... when the number of segments reaches the gro_normal_batch limit.

> +
> +Default : 8

Also, should we drop the default? It's easy to grep for, chances are if
anyone updates the value they will forget to change the doc.

Sorry for the late review, I wasn't expecting v3 will be needed.

>  2. /proc/sys/net/unix - Parameters for Unix domain sockets
>  ----------------------------------------------------------
>