On Wed, 10 Sep 2025 08:49:38 +0200 Thierry Herbelot <thierry.herbe...@6wind.com> wrote:
> Hello Stephen, > > On 9/9/25 18:17, Stephen Hemminger wrote: > > On Tue, 9 Sep 2025 07:40:23 +0200 > > Thierry Herbelot <thierry.herbe...@6wind.com> wrote: > > > >> The qede PMD stopped working under Ubuntu-24.04 (using gcc-13) when > >> compiled with -O3 (default level for all DPDK code). A bug is opened > >> for this issue (see Link). The same issue is also seen with gcc-12 > >> and gcc-14. The issue is not seen with clang-20. > >> > >> A first workaround is to just disable all optimizations (-O0), which > >> restores packet Rx with Qlogic NICs. However, the performance impact > >> is not acceptable (around 50% drop). > >> > >> A better compromise is to use -O1 for the qede PMD: > >> - there is some perf impact, > >> - but the PMD is working as expected (packets are correctly received). > >> > >> When compiling with both -O2 and -O3 and gcc > 11, there is no packet > >> reception when using the qede PMD. The root cause could be missing > >> 'volatile' keywords or missing memory barriers in the qede PMD code. > >> > >> Link: https://bugs.dpdk.org/show_bug.cgi?id=1379 > >> Signed-off-by: Thierry Herbelot <thierry.herbe...@6wind.com> > > > > Which rx_burst gets used on that hardware? > > > > Is there any indication of errors (like rx_mbuf_alloc_failed) in the stats. > > > > The driver does not appear to have any write barrier after updating the > > consumed packets. > > > > Would this help? > > diff --git a/drivers/net/qede/qede_rxtx.c b/drivers/net/qede/qede_rxtx.c > > index 25e28fd9f6..1b5109d966 100644 > > --- a/drivers/net/qede/qede_rxtx.c > > +++ b/drivers/net/qede/qede_rxtx.c > > @@ -1295,6 +1295,8 @@ static inline void qede_rx_bd_ring_consume(struct > > qede_rx_queue *rxq) > > { > > ecore_chain_consume(&rxq->rx_bd_ring); > > rxq->sw_rx_cons++; > > + > > + rte_wmb(); > > } > > > I just checked with this patch, but the error is still present: > > testpmd> show fwd stats all > > ---------------------- Forward statistics for port 0 > ---------------------- > RX-packets: 0 RX-dropped: 10 RX-total: 10 > RX-error: 0 > RX-nombufs: 10 > TX-packets: 0 TX-dropped: 0 TX-total: 0 > > ---------------------------------------------------------------------------- > > The error chain is: > > RX-nombufs > => (testpmd) stats.rx_nombuf > => (qede) p_stats->common.no_buff_discards > => (qede/base) HILO_64_REGPAIR(mstats.no_buff_discard) > (internal to the NIC) > Thanks, lets root cause this (rather than paper it over) because other drivers may have same issue. Since no mbufs are present looks like rx discriptor never made it to NIC
