netdev - Re: [PATCH V3 net-next 0/3] RDS: optimized notification for zerocopy completion

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Date:   Mon, 26 Feb 2018 11:56:55 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Sowmini Varadhan <sowmini.varadhan@...cle.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Santosh Shilimkar <santosh.shilimkar@...cle.com>
Subject: Re: [PATCH V3 net-next 0/3] RDS: optimized notification for zerocopy completion

On Sun, Feb 25, 2018 at 6:21 PM, Sowmini Varadhan
<sowmini.varadhan@...cle.com> wrote:
> RDS applications use predominantly request-response, transacation
> based IPC, so that ingress and egress traffic are well-balanced,
> and it is possible/desirable to reduce system-call overhead by
> piggybacking the notifications for zerocopy completion response
> with data.
>
> Moreover, it has been pointed out that socket functions block
> if sk_err is non-zero, thus if the RDS code does not plan/need
> to use sk_error_queue path for completion notification, it
> is preferable to remove the sk_errror_queue related paths in
> RDS.
>
> Both of these goals are implemented in this series.
>
> v2: removed sk_error_queue support
> v3: incorporated additional code review comments (details in each patch)
>
> Sowmini Varadhan (3):
>   selftests/net: revert the zerocopy Rx path for PF_RDS
>   rds: deliver zerocopy completion notification with data
>   selftests/net: reap zerocopy completions passed up as ancillary data.
>
>  include/uapi/linux/errqueue.h              |    2 -
>  include/uapi/linux/rds.h                   |    7 ++
>  net/rds/af_rds.c                           |    7 +-
>  net/rds/message.c                          |   38 ++++-----
>  net/rds/rds.h                              |    2 +
>  net/rds/recv.c                             |   31 +++++++-
>  tools/testing/selftests/net/msg_zerocopy.c |  120 ++++++++++++----------------
>  7 files changed, 111 insertions(+), 96 deletions(-)

For the series:

Acked-by Willem de Bruijn <willemb@...gle.com>

Small item I missed in v2: the recvmsg in patch 3 should fail hard with
error() on an unexpected errno. Not worth sending a v4 just for that.