Hi Michael, Following the polling patch thread: http://marc.info/?l=kvm&m=140853271510179&w=2, I changed poll_stop_idle to be counted in micro seconds, and carried out experiments using varying sizes of this value. The setup for netperf consisted of 1 vm and 1 vhost , each running on their own dedicated core. Here are the numbers for netperf (micro benchmark): polling|Send |Throughput|Utilization |S. Demand |vhost|exits|throughput|throughput mode |Msg | |Send Recv |Send Recv |util |/sec | /cpu | /cpu |Size | |local remote|local remote| | | |% change |bytes|10^6bits/s| % % |us/KB us/KB | % | | | ----------------------------------------------------------------------------- NoPolling 64 1054.11 99.97 3.01 7.78 3.74 38.80 92K 7.60 Polling=1 64 1036.67 99.97 2.93 7.90 3.70 53.00 92K 6.78 -10.78 Polling=5 64 1079.27 99.97 3.07 7.59 3.73 83.00 90K 5.90 -22.35 Polling=7 64 1444.90 99.97 3.98 5.67 3.61 95.00 19.5K 7.41 -2.44 Polling=10 64 1521.70 99.97 4.21 5.38 3.63 98.00 8.5K 7.69 1.19 Polling=25 64 1534.24 99.97 4.18 5.34 3.57 99.00 8.5K 7.71 1.51 Polling=50 64 1534.24 99.97 4.18 5.34 3.57 99.00 8.5K 7.71 1.51 NoPolling 128 1577.39 99.97 4.09 5.19 3.40 54.00 113K 10.24 Polling=1 128 1596.08 99.97 4.22 5.13 3.47 71.00 120K 9.34 -8.88 Polling=5 128 2238.49 99.97 5.45 3.66 3.19 92.00 24K 11.66 13.82 Polling=7 128 2330.97 99.97 5.59 3.51 3.14 95.00 19.5K 11.96 16.70 Polling=10 128 2375.78 99.97 5.69 3.45 3.14 98.00 10K 12.00 17.14 Polling=25 128 2655.01 99.97 2.45 3.09 1.21 99.00 8.5K 13.34 30.25 Polling=50 128 2655.01 99.97 2.45 3.09 1.21 99.00 8.5K 13.34 30.25 NoPolling 25 2558.10 99.97 2.33 3.20 1.20 67.00 120K 15.32 Polling=1 25 2508.93 99.97 3.13 3.27 1.67 75.00 125K 14.34 -6.41 Polling=5 25 3740.34 99.97 2.70 2.19 0.95 94.00 17K 19.28 25.86 Polling=7 25 3692.69 99.97 2.80 2.22 0.99 97.00 15.5K 18.75 22.37 Polling=10 25 4036.60 99.97 2.69 2.03 0.87 99.00 8.5K 20.29 32.42 Polling=25 25 3998.89 99.97 2.64 2.05 0.87 99.00 8.5K 20.10 31.18 Polling=50 25 3998.89 99.97 2.64 2.05 0.87 99.00 8.5K 20.10 31.18 NoPolling 512 4531.50 99.90 2.75 1.81 0.79 78.00 55K 25.47 Polling=1 512 4684.19 99.95 2.69 1.75 0.75 83.00 35K 25.60 0.52 Polling=5 512 4932.65 99.75 2.75 1.68 0.74 91.00 12K 25.86 1.52 Polling=7 512 5226.14 99.86 2.80 1.57 0.70 95.00 7.5K 26.82 5.30 Polling=10 512 5464.90 99.60 2.90 1.49 0.70 96.00 8.2K 27.94 9.69 Polling=25 512 5550.44 99.58 2.84 1.47 0.67 99.00 7.5K 27.95 9.73 Polling=50 512 5550.44 99.58 2.84 1.47 0.67 99.00 7.5K 27.95 9.73 As you can see from the last column, polling improves performance in most cases. I ran memcached (macro benchmark), where (as in the previous benchmark) the vm and vhost each get their own dedicated core. I configured memslap with C=128, T=8, as this configuration was required to produce enough load to saturate the vm. I tried several other configurations, but this one produced the maximal throughput(for the baseline). The numbers for memcached (macro benchmark): polling time TPS Net vhost vm exits TPS/cpu TPS/cpu mode rate util util /sec % change % Disabled 15.9s 125819 91.5 45 99 87K 873.74 polling=1 15.8s 126820 92.3 60 99 87K 797.61 -8.71 polling=5 12.82 155799 113.4 79 99 25.5K 875.28 0.18 polling=10 11.7s 160639 116.9 83 99 16.3K 882.63 1.02 pollling=15 12.4s 160897 117.2 87 99 15K 865.04 -1.00 polling=100 11.7s 170971 124.4 99 99 30 863.49 -1.17 For memcached TPS/cpu does not show a significant difference in any of the cases. However, TPS numbers did improve in up to 35%, which can be useful for under-utilized systems which have cpu time to spare for extra throughput. If it makes sense to you, I will continue with the other changes requested for the patch. Thank you, Razya -- 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
