Michael S. Tsirkin
2018-Apr-09 05:46 UTC
[PATCH] vhost-net: set packet weight of tx polling to 2 * vq size
On Mon, Apr 09, 2018 at 04:09:20AM +0000, haibinzhang(???) wrote:> > > On Fri, Apr 06, 2018 at 08:22:37AM +0000, haibinzhang(???) wrote: > > > handle_tx will delay rx for tens or even hundreds of milliseconds when tx busy > > > polling udp packets with small length(e.g. 1byte udp payload), because setting > > > VHOST_NET_WEIGHT takes into account only sent-bytes but no single packet length. > > > > > > Ping-Latencies shown below were tested between two Virtual Machines using > > > netperf (UDP_STREAM, len=1), and then another machine pinged the client: > > > > > > Packet-Weight Ping-Latencies(millisecond) > > > min avg max > > > Origin 3.319 18.489 57.303 > > > 64 1.643 2.021 2.552 > > > 128 1.825 2.600 3.224 > > > 256 1.997 2.710 4.295 > > > 512 1.860 3.171 4.631 > > > 1024 2.002 4.173 9.056 > > > 2048 2.257 5.650 9.688 > > > 4096 2.093 8.508 15.943 > > > > And this is with Q size 256 right? > > Yes. Ping-latencies with 512 VQ size show below. > > Packet-Weight Ping-Latencies(millisecond) > min avg max > Origin 6.357 29.177 66.245 > 64 2.798 3.614 4.403 > 128 2.861 3.820 4.775 > 256 3.008 4.018 4.807 > 512 3.254 4.523 5.824 > 1024 3.079 5.335 7.747 > 2048 3.944 8.201 12.762 > 4096 4.158 11.057 19.985 > > We will submit again. Is there anything else?Seems pretty consistent, a small dip at 2 VQ sizes. Acked-by: Michael S. Tsirkin <mst at redhat.com>> > > > > Ring size is a hint from device about a burst size it can tolerate. Based on > > > benchmarks, set the weight to 2 * vq size. > > > > > > To evaluate this change, another tests were done using netperf(RR, TX) between > > > two machines with Intel(R) Xeon(R) Gold 6133 CPU @ 2.50GHz, and vq size was > > > tweaked through qemu. Results shown below does not show obvious changes. > > > > What I asked for is ping-latency with different VQ sizes, > > streaming below does not show anything. > > > > > vq size=256 TCP_RR vq size=512 TCP_RR > > > size/sessions/+thu%/+normalize% size/sessions/+thu%/+normalize% > > > 1/ 1/ -7%/ -2% 1/ 1/ 0%/ -2% > > > 1/ 4/ +1%/ 0% 1/ 4/ +1%/ 0% > > > 1/ 8/ +1%/ -2% 1/ 8/ 0%/ +1% > > > 64/ 1/ -6%/ 0% 64/ 1/ +7%/ +3% > > > 64/ 4/ 0%/ +2% 64/ 4/ -1%/ +1% > > > 64/ 8/ 0%/ 0% 64/ 8/ -1%/ -2% > > > 256/ 1/ -3%/ -4% 256/ 1/ -4%/ -2% > > > 256/ 4/ +3%/ +4% 256/ 4/ +1%/ +2% > > > 256/ 8/ +2%/ 0% 256/ 8/ +1%/ -1% > > > > > > vq size=256 UDP_RR vq size=512 UDP_RR > > > size/sessions/+thu%/+normalize% size/sessions/+thu%/+normalize% > > > 1/ 1/ -5%/ +1% 1/ 1/ -3%/ -2% > > > 1/ 4/ +4%/ +1% 1/ 4/ -2%/ +2% > > > 1/ 8/ -1%/ -1% 1/ 8/ -1%/ 0% > > > 64/ 1/ -2%/ -3% 64/ 1/ +1%/ +1% > > > 64/ 4/ -5%/ -1% 64/ 4/ +2%/ 0% > > > 64/ 8/ 0%/ -1% 64/ 8/ -2%/ +1% > > > 256/ 1/ +7%/ +1% 256/ 1/ -7%/ 0% > > > 256/ 4/ +1%/ +1% 256/ 4/ -3%/ -4% > > > 256/ 8/ +2%/ +2% 256/ 8/ +1%/ +1% > > > > > > vq size=256 TCP_STREAM vq size=512 TCP_STREAM > > > size/sessions/+thu%/+normalize% size/sessions/+thu%/+normalize% > > > 64/ 1/ 0%/ -3% 64/ 1/ 0%/ 0% > > > 64/ 4/ +3%/ -1% 64/ 4/ -2%/ +4% > > > 64/ 8/ +9%/ -4% 64/ 8/ -1%/ +2% > > > 256/ 1/ +1%/ -4% 256/ 1/ +1%/ +1% > > > 256/ 4/ -1%/ -1% 256/ 4/ -3%/ 0% > > > 256/ 8/ +7%/ +5% 256/ 8/ -3%/ 0% > > > 512/ 1/ +1%/ 0% 512/ 1/ -1%/ -1% > > > 512/ 4/ +1%/ -1% 512/ 4/ 0%/ 0% > > > 512/ 8/ +7%/ -5% 512/ 8/ +6%/ -1% > > > 1024/ 1/ 0%/ -1% 1024/ 1/ 0%/ +1% > > > 1024/ 4/ +3%/ 0% 1024/ 4/ +1%/ 0% > > > 1024/ 8/ +8%/ +5% 1024/ 8/ -1%/ 0% > > > 2048/ 1/ +2%/ +2% 2048/ 1/ -1%/ 0% > > > 2048/ 4/ +1%/ 0% 2048/ 4/ 0%/ -1% > > > 2048/ 8/ -2%/ 0% 2048/ 8/ 5%/ -1% > > > 4096/ 1/ -2%/ 0% 4096/ 1/ -2%/ 0% > > > 4096/ 4/ +2%/ 0% 4096/ 4/ 0%/ 0% > > > 4096/ 8/ +9%/ -2% 4096/ 8/ -5%/ -1% > > > > > > Signed-off-by: Haibin Zhang <haibinzhang at tencent.com> > > > Signed-off-by: Yunfang Tai <yunfangtai at tencent.com> > > > Signed-off-by: Lidong Chen <lidongchen at tencent.com> > > > > Code is fine but I'd like to see validation of the heuristic > > 2*vq->num with another vq size. > > > > > > > > > --- > > > drivers/vhost/net.c | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > > > index 8139bc70ad7d..3563a305cc0a 100644 > > > --- a/drivers/vhost/net.c > > > +++ b/drivers/vhost/net.c > > > @@ -44,6 +44,10 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;" > > > * Using this limit prevents one virtqueue from starving others. */ > > > #define VHOST_NET_WEIGHT 0x80000 > > > > > > +/* Max number of packets transferred before requeueing the job. > > > + * Using this limit prevents one virtqueue from starving rx. */ > > > +#define VHOST_NET_PKT_WEIGHT(vq) ((vq)->num * 2) > > > + > > > /* MAX number of TX used buffers for outstanding zerocopy */ > > > #define VHOST_MAX_PEND 128 > > > #define VHOST_GOODCOPY_LEN 256 > > > @@ -473,6 +477,7 @@ static void handle_tx(struct vhost_net *net) > > > struct socket *sock; > > > struct vhost_net_ubuf_ref *uninitialized_var(ubufs); > > > bool zcopy, zcopy_used; > > > + int sent_pkts = 0; > > > > > > mutex_lock(&vq->mutex); > > > sock = vq->private_data; > > > @@ -580,7 +585,8 @@ static void handle_tx(struct vhost_net *net) > > > else > > > vhost_zerocopy_signal_used(net, vq); > > > vhost_net_tx_packet(net); > > > - if (unlikely(total_len >= VHOST_NET_WEIGHT)) { > > > + if (unlikely(total_len >= VHOST_NET_WEIGHT) || > > > + unlikely(++sent_pkts >= VHOST_NET_PKT_WEIGHT(vq))) { > > > vhost_poll_queue(&vq->poll); > > > break; > > > } > > > -- > > > 2.12.3 > > > >
Maybe Matching Threads
- [PATCH] vhost-net: set packet weight of tx polling to 2 * vq size
- [PATCH] vhost-net: add limitation of sent packets for tx polling
- [PATCH] vhost-net: add limitation of sent packets for tx polling
- [PATCH] vhost-net: set packet weight of tx polling to 2 * vq size
- [PATCH RESEND v2] vhost-net: set packet weight of tx polling to 2 * vq size
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