On Tue, Jul 03, 2018 at 04:31:30PM +0900, Toshiaki Makita wrote: > Under heavy load vhost tx busypoll tend not to suppress vq kicks, which > causes poor guest tx performance. The detailed scenario is described in > commitlog of patch 2. > Rx seems not to have that serious problem, but for consistency I made a > similar change on rx to avoid rx wakeups (patch 3). > Additionary patch 4 is to avoid rx kicks under heavy load during > busypoll. > > Tx performance is greatly improved by this change. I don't see notable > performance change on rx with this series though. > > Performance numbers (tx): > > - Bulk transfer from guest to external physical server. > [Guest]->vhost_net->tap--(XDP_REDIRECT)-->i40e --(wire)--> [Server] > - Set 10us busypoll. > - Guest disables checksum and TSO because of host XDP. > - Measured single flow Mbps by netperf, and kicks by perf kvm stat > (EPT_MISCONFIG event). > > Before After > Mbps kicks/s Mbps kicks/s > UDP_STREAM 1472byte 247758 27 > Send 3645.37 6958.10 > Recv 3588.56 6958.10 > 1byte 9865 37 > Send 4.34 5.43 > Recv 4.17 5.26 > TCP_STREAM 8801.03 45794 9592.77 2884 Thanks! Series: Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > v2: > - Split patches into 3 parts (renaming variables, tx-kick fix, rx-wakeup > fix). > - Avoid rx-kicks too (patch 4). > - Don't memorize endtime as it is not needed for now. > > Toshiaki Makita (4): > vhost_net: Rename local variables in vhost_net_rx_peek_head_len > vhost_net: Avoid tx vring kicks during busyloop > vhost_net: Avoid rx queue wake-ups during busypoll > vhost_net: Avoid rx vring kicks during busyloop > > drivers/vhost/net.c | 95 +++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 60 insertions(+), 35 deletions(-) > > -- > 1.8.3.1 >
