On Fri, Jul 8, 2022 at 10:18 PM Pai G, Sunil <[email protected]> wrote:
>
> Hi Kevin,
>
Hi Sunil,
thanks for reviewing the patches.
> Thanks for the patch.
> LGTM in general, couple of minor comments/thoughts inline.
>
> <snipped>
>
> > +struct user_mempool_config {
> > + int adj_mtu;
> > + int socket_id;
> > +};
> > +
> > +static struct user_mempool_config *user_mempools = NULL; static int
> > +n_user_mempools;
>
> Should we consider restricting n_user_mempools to some max value ?
>
We could do. There is no issue with having many values, it just might
not make much sense for a user.
Is your concern that someone might maliciously keep adding values?
I'm not sure if there is some protection already within the smap_get
that would prevent this. i'd need to check that.
If there is, then that would be covered already. Otherwise we could
add some arbitrary max number like 100.
> >
> > /* There should be one 'struct dpdk_tx_queue' created for @@ -573,4
> > +582,42 @@ dpdk_buf_size(int mtu) }
> >
> > +static int
> > +dpdk_get_user_adjusted_mtu(int port_adj_mtu, int port_mtu, int
> > +port_socket_id) {
> > + int best_adj_user_mtu = INT_MAX;
> > +
> > + for (unsigned i = 0; i < n_user_mempools; i++) {
> > + int user_adj_mtu, user_socket_id;
> > +
> > + user_adj_mtu = user_mempools[i].adj_mtu;
> > + user_socket_id = user_mempools[i].socket_id;
> > + if (port_adj_mtu > user_adj_mtu
> > + || (user_socket_id != INT_MAX
> > + && user_socket_id != port_socket_id)) {
> > + continue;
> > + }
> > + if (user_adj_mtu < best_adj_user_mtu) {
> > + /* This is the is the lowest valid user MTU. */
> > + best_adj_user_mtu = user_adj_mtu;
> > + if (best_adj_user_mtu == port_adj_mtu) {
> > + /* Found an exact fit, no need to keep searching. */
> > + break;
> > + }
> > + }
>
>
> I guess this is more appropriate than sorting etc to find lowest valid user
> MTU since we assume n_user_mempools will be quite small ?
>
It is relying on MTU *and* socket id (which may be wildcard/any NUMA),
so we couldn't sort it as a flat list.
There would need to be multiple lists created for every numa etc
There is no need to go to that trouble to speed up the look up when we
expect a few entries and we only look this up on the control path
when we are changing MTU. So I think it's fine the way it is.
Kevin.
> > + }
> > + if (best_adj_user_mtu == INT_MAX) {
> > + VLOG_DBG("No user configured shared mempool mbuf sizes found "
> > + "suitable for port with MTU %d, NUMA %d.", port_mtu,
> > + port_socket_id);
> > + best_adj_user_mtu = port_adj_mtu;
> > + } else {
> > + VLOG_DBG("Found user configured shared mempool with mbufs "
> > + "of size %d, suitable for port with MTU %d, NUMA %d.",
> > + MTU_TO_FRAME_LEN(best_adj_user_mtu), port_mtu,
> > + port_socket_id);
> > + }
> > + return best_adj_user_mtu;
> > +}
> > +
>
> <snipped>
>
> Thanks and regards,
> Sunil
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