Hi Maxime and other maintainers, On Fri, Jul 4, 2025 at 7:57 PM Maxime Coquelin <maxime.coque...@redhat.com> wrote: > > Hi Yu, Hengqi, > > First, thanks Yu for testing and reporting the performance degradation, > this is much appreciated! > > On 7/4/25 1:29 PM, Jiang, YuX wrote: > > Hi Hengqi, > > > > Can you help to check the ticket: > > https://bugs.dpdk.org/show_bug.cgi?id=1747? The perf drop is caused by your > > patch. Thanks so much. > > The options I see are: > 1. Revert the patch for v25.07, fix it and resubmit for v25.11. > 2. Fix it on time for v25.07-rc3 > 3. Keep the patch in v25.07 and try to fix it in v25.11. > > As I will be OoO starting this evening, I would be in favor of option 1. > What do you think? >
I am OK with both option 1 and 3. Please handle it according to the DPDK community rules. Thanks, Hengqi > Thanks, > Maxime > > > Best regards, > > Yu Jiang > > > >> -----Original Message----- > >> From: Hengqi Chen <hengqi.c...@gmail.com> > >> Sent: Monday, June 9, 2025 3:24 PM > >> To: dev@dpdk.org > >> Cc: Hengqi Chen <hengqi.c...@gmail.com>; Baoyuan Li > >> <updo...@sina.com>; Maxime Coquelin <maxime.coque...@redhat.com>; > >> Chenbo Xia <chen...@nvidia.com> > >> Subject: [PATCH] net/virtio: Fix check of threshold for Tx freeing > >> > >> Like most dirvers, make the fast path of virtio_xmit_cleanup() behave as > >> described by the comments of rte_eth_txconf::tx_free_thresh ([0]): > >> Start freeing Tx buffers if there are > >> less free descriptors than this value. > >> > >> The rationale behind this change is that: > >> * vq->vq_nentries is set during device probe with the queue size > >> specified > >> by vhost backend, this value does not reflect the real nb_tx_desc > >> * the real available tx desc is set to vq->vq_free_cnt via the > >> nb_tx_desc > >> param of rte_eth_tx_queue_setup() API > >> * so `nb_used > vq->vq_nentries - vq->vq_free_thresh` could never be > >> true > >> if say nb_tx_desc=2048, vq->vq_nentries=4096, vq->vq_free_thresh=32, > >> see bug report 1716 ([1]) for details. > >> > >> Bugzilla ID: 1716 > >> > >> [0]: https://github.com/DPDK/dpdk/commit/72514b5d5543 > >> [1]: https://bugs.dpdk.org/show_bug.cgi?id=1716 > >> > >> Signed-off-by: Baoyuan Li <updo...@sina.com> > >> Signed-off-by: Hengqi Chen <hengqi.c...@gmail.com> > >> --- > >> drivers/net/virtio/virtio_rxtx.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/net/virtio/virtio_rxtx.c > >> b/drivers/net/virtio/virtio_rxtx.c > >> index edecd2011f..ab97f03d7d 100644 > >> --- a/drivers/net/virtio/virtio_rxtx.c > >> +++ b/drivers/net/virtio/virtio_rxtx.c > >> @@ -1873,7 +1873,7 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf > >> **tx_pkts, uint16_t nb_pkts) > >> > >> nb_used = virtqueue_nused(vq); > >> > >> - if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh)) > >> + if (likely(vq->vq_free_cnt < vq->vq_free_thresh)) > >> virtio_xmit_cleanup(vq, nb_used); > >> > >> for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) { > >> -- > >> 2.43.5 > > >
