Hi Joyce, I just test performance impact of your patch set with code base commit id: d03d8622db48918d14bfe805641b1766ecc40088, after applying your v3 patch set , seven paths of vhost/virtio pvp test shows performance drop as below:
PVP vhost/virtio 1c1q test before apply patch apply patch test_perf_pvp_inorder_mergeable 7.603 7.474 test_perf_pvp_inorder_no_mergeable 7.642 7.525 test_perf_pvp_mergeable 7.556 7.431 test_perf_pvp_normal 7.554 7.478 test_perf_pvp_vector_rx 7.581 7.469 test_perf_pvp_virtio11_mergeable 7.068 6.905 test_perf_pvp_virtio11_normal 7.088 6.888 Thanks, Yinan > -----Original Message----- > From: dev [mailto:[email protected]] On Behalf Of Maxime Coquelin > Sent: 2019年9月9日 18:10 > To: Joyce Kong <[email protected]>; [email protected] > Cc: [email protected]; Bie, Tiwei <[email protected]>; Wang, Zhihong > <[email protected]>; [email protected]; Wang, Xiao W > <[email protected]>; Liu, Yong <[email protected]>; > [email protected]; [email protected]; [email protected] > Subject: Re: [dpdk-dev] [PATCH v3 1/2] virtio: one way barrier for packed > vring > desc avail flags > > > > On 9/9/19 11:14 AM, Joyce Kong wrote: > > In case VIRTIO_F_ORDER_PLATFORM(36) is not negotiated, then the > > frontend and backend are assumed to be implemented in software, that > > is they can run on identical CPUs in an SMP configuration. > > Thus a weak form of memory barriers like rte_smp_r/wmb, other than > > rte_cio_r/wmb, is sufficient for this case(vq->hw->weak_barriers == 1) > > and yields better performance. > > For the above case, this patch helps yielding even better performance > > by replacing the two-way barriers with C11 one-way barriers for avail > > flags in packed ring. > > > > Meanwhile, a read barrier is required to ensure ordering between > > descriptor's flags and content reads[1]. With C11, load-acquire can > > enforce the ordering instead of rmb barrier. > > > > [1]https://patchwork.dpdk.org/patch/49109/ > > > > Signed-off-by: Joyce Kong <[email protected]> > > Reviewed-by: Gavin Hu <[email protected]> > > Reviewed-by: Phil Yang <[email protected]> > > --- > > drivers/net/virtio/virtio_rxtx.c | 13 +++++++------ > > drivers/net/virtio/virtio_user/virtio_user_dev.c | 6 +++++- > > drivers/net/virtio/virtqueue.h | 11 +++++++++++ > > lib/librte_vhost/vhost.h | 2 +- > > lib/librte_vhost/virtio_net.c | 11 +++++------ > > 5 files changed, 29 insertions(+), 14 deletions(-) > > Reviewed-by: Maxime Coquelin <[email protected]> > > Thanks, > Maxime
