Krishna Kumar2/India/IBM wrote on 10/26/2010 10:40:35 AM: > > I am trying to wrap my head around kernel/user interface here. > > E.g., will we need another incompatible change when we add multiple RX > > queues? > > Though I added a 'mq' option to qemu, there shouldn't be > any incompatibility between old and new qemu's wrt vhost > and virtio-net drivers. So the old qemu will run new host > and new guest without issues, and new qemu can also run > old host and old guest. Multiple RXQ will also not add > any incompatibility. > > With MQ RX, I will be able to remove the hueristic (idea > from David Stevens). The idea is: Guest sends out packets > on, say TXQ#2, vhost#2 processes the packets but packets > going out from host to guest might be sent out on a > different RXQ, say RXQ#4. Guest receives the packet on > RXQ#4, and all future responses on that connection are sent > on TXQ#4. Now vhost#4 processes both RX and TX packets for > this connection. Without needing to hash on the connection, > guest can make sure that the same vhost thread will handle > a single connection. > > > Also need to think about how robust our single stream heuristic is, > > e.g. what are the chances it will misdetect a bidirectional > > UDP stream as a single TCP? > I think it should not happen. The hueristic code gets > called for handling just the transmit packets, packets > that vhost sends out to the guest skip this path. > > I tested unidirectional and bidirectional UDP to confirm: > > 8 iterations of iperf tests, each iteration of 15 secs, > result is the sum of all 8 iterations in Gbits/sec > __________________________________________ > Uni-directional Bi-directional > Org New Org New > __________________________________________ > 71.78 71.77 71.74 72.07 > __________________________________________ Results for UDP BW tests (unidirectional, sum across 3 iterations, each iteration of 45 seconds, default netperf, vhosts bound to cpus 0-3; no other tuning): ------ numtxqs=8, vhosts=5 --------- # BW% CPU% SD% ------------------------------------ 1 .49 1.07 0 2 23.51 52.51 26.66 4 75.17 72.43 8.57 8 86.54 80.21 27.85 16 92.37 85.99 6.27 24 91.37 84.91 8.41 32 89.78 82.90 3.31 48 89.85 79.95 -3.57 64 85.83 80.28 2.22 80 88.90 79.47 -23.18 96 90.12 79.98 14.71 128 86.13 80.60 4.42 ------------------------------------ BW: 71.3%, CPU: 80.4%, SD: 1.2% ------ numtxqs=16, vhosts=5 -------- # BW% CPU% SD% ------------------------------------ 1 1.80 0 0 2 19.81 50.68 26.66 4 57.31 52.77 8.57 8 108.44 88.19 -5.21 16 106.09 85.03 -4.44 24 102.34 84.23 -.82 32 102.77 82.71 -5.81 48 100.00 79.62 -7.29 64 96.86 79.75 -6.10 80 99.26 79.82 -27.34 96 94.79 80.02 -5.08 128 98.14 81.15 -15.25 ------------------------------------ BW: 77.9%, CPU: 80.4%, SD: -13.6% Thanks, - KK -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
