Re: [PATCH net-next] udp: add local "peek offset enabled" flag

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Eric Dumazet wrote:
> On Tue, Feb 20, 2024 at 12:00 PM Paolo Abeni <pabeni@redhat.com> wrote:
> >
> > We want to re-organize the struct sock layout. The sk_peek_off
> > field location is problematic, as most protocols want it in the
> > RX read area, while UDP wants it on a cacheline different from
> > sk_receive_queue.
> >
> > Create a local (inside udp_sock) copy of the 'peek offset is enabled'
> > flag and place it inside the same cacheline of reader_queue.
> >
> > Check such flag before reading sk_peek_off. This will save potential
> > false sharing and cache misses in the fast-path.
> >
> > Tested under UDP flood with small packets. The struct sock layout
> > update causes a 4% performance drop, and this patch restores completely
> > the original tput.
> >
> > Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> > ---
> 
> SGTM, thanks !
> Reviewed-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Willem de Bruijn <willemb@google.com>