> On 1 Jun 2021, at 04:15, Patrick Wildt <[email protected]> wrote:
>
> Hi,
>
> mcx(4) seems to sync the whole mapsize on processing a received packet.
> As far as I know, we usually only sync the actual size that we have
> received. Noticed this when doing bounce buffer tests, seeing that
> it copied a lot more data than is necessary.
>
> That's because the RX buffer size is maximum supported MTU, which is
> about 9500 bytes or so. For small packets, or regular 1500 bytes,
> this adds overhead.
>
> This change should not change anything for ARM machines that have a
> cache coherent PCIe bus or x86.
>
> ok?
ok.
>
> Patrick
>
> diff --git a/sys/dev/pci/if_mcx.c b/sys/dev/pci/if_mcx.c
> index 38437e54897..065855d46d3 100644
> --- a/sys/dev/pci/if_mcx.c
> +++ b/sys/dev/pci/if_mcx.c
> @@ -6800,20 +6800,20 @@ mcx_process_rx(struct mcx_softc *sc, struct mcx_rx
> *rx,
> {
> struct mcx_slot *ms;
> struct mbuf *m;
> - uint32_t flags;
> + uint32_t flags, len;
> int slot;
>
> + len = bemtoh32(&cqe->cq_byte_cnt);
> slot = betoh16(cqe->cq_wqe_count) % (1 << MCX_LOG_RQ_SIZE);
>
> ms = &rx->rx_slots[slot];
> - bus_dmamap_sync(sc->sc_dmat, ms->ms_map, 0, ms->ms_map->dm_mapsize,
> - BUS_DMASYNC_POSTREAD);
> + bus_dmamap_sync(sc->sc_dmat, ms->ms_map, 0, len, BUS_DMASYNC_POSTREAD);
> bus_dmamap_unload(sc->sc_dmat, ms->ms_map);
>
> m = ms->ms_m;
> ms->ms_m = NULL;
>
> - m->m_pkthdr.len = m->m_len = bemtoh32(&cqe->cq_byte_cnt);
> + m->m_pkthdr.len = m->m_len = len;
>
> if (cqe->cq_rx_hash_type) {
> m->m_pkthdr.ph_flowid = betoh32(cqe->cq_rx_hash);
>
