On Tue, Jun 01, 2021 at 08:20:43AM +1000, David Gwynne wrote:
>
>
> > 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.
ok by me too.
>
> >
> > 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);
> >
>
