Re: [PATCH v2 net] splice: do not checksum AF_UNIX sockets

[Joe Damato]

On Mon, Dec 09, 2024 at 09:06:48PM -0800, Frederik Deweerdt wrote:
> When `skb_splice_from_iter` was introduced, it inadvertently added
> checksumming for AF_UNIX sockets. This resulted in significant
> slowdowns, for example when using sendfile over unix sockets.
> 
> Using the test code in [1] in my test setup (2G single core qemu),
> the client receives a 1000M file in:
> - without the patch: 1482ms (+/- 36ms)
> - with the patch: 652.5ms (+/- 22.9ms)
> 
> This commit addresses the issue by marking checksumming as unnecessary in
> `unix_stream_sendmsg`
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Frederik Deweerdt <deweerdt.lkml@xxxxxxxxx>
> Fixes: 2e910b95329c ("net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES")
> ---
>  net/unix/af_unix.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Joe Damato <jdamato@xxxxxxxxxx>