On 2/29/2024 5:56 PM, Stephen Hemminger wrote:
> The tap device needs to exchange file descriptors for tx and rx.
> But the EAL MP layer has limit of 8 file descriptors per message.
> The ideal resolution would be to increase the number of file
> descriptors allowed for rte_mp_sendmsg(), but this would break
> the ABI. Workaround the constraint by breaking into multiple messages.
>
> Do not hide errors about MP message failures.
>
> Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> ---
> drivers/net/tap/rte_eth_tap.c | 40 +++++++++++++++++++++++++++++------
> 1 file changed, 33 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index 69d9da695bed..df18c328f498 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -863,21 +863,44 @@ tap_mp_req_on_rxtx(struct rte_eth_dev *dev)
> msg.fds[fd_iterator++] = process_private->txq_fds[i];
> msg.num_fds++;
> request_param->txq_count++;
> +
> + /* Need to break request into chunks */
> + if (fd_iterator >= RTE_MP_MAX_FD_NUM) {
> + err = rte_mp_sendmsg(&msg);
> + if (err < 0)
> + goto fail;
> +
> + fd_iterator = 0;
> + msg.num_fds = 0;
> + request_param->txq_count = 0;
> + }
> }
> for (i = 0; i < dev->data->nb_rx_queues; i++) {
> msg.fds[fd_iterator++] = process_private->rxq_fds[i];
> msg.num_fds++;
> request_param->rxq_count++;
> +
> + if (fd_iterator >= RTE_MP_MAX_FD_NUM) {
> + err = rte_mp_sendmsg(&msg);
> + if (err < 0)
> + goto fail;
> +
> + fd_iterator = 0;
> + msg.num_fds = 0;
> + request_param->rxq_count = 0;
> + }
> }
Hi Stephen,
Did you able to verify with more than 4 queues?
As far as I can see, in the secondary counterpart of the
'rte_mp_sendmsg()', each time secondary index starts from 0, and
subsequent calls overwrites the fds in secondary.
So practically still only 4 queues works.
