This patch will change vhost TX used buffer guest signaling from one by one to 3/4 ring size. I have tried different size, like 4, 16, 1/4 size, 1/2 size, and found that the large size is best for message size between 256 - 4K with netperf TCP_STREAM test, so 3/4 of the ring size is picked up for signaling. Tested both UDP and TCP performance with guest 2vcpu. The 60 secs netperf run shows that guest to host performance for TCP. TCP_STREAM Message size Guest CPU(%) BW (Mb/s) before:after before:after 256 57.84:58.42 1678.47:1908.75 512 68.68:60.21 1844.18:3387.33 1024 68.01:58.70 1945.14:3384.72 2048 65.36:54.25 2342.45:3799.31 4096 63.25:54.62 3307.11:4451.78 8192 59.57:57.89 6038.64:6694.04 UDP_STREAM 1024 49.64:26.69 1161.0:1687.6 2048 49.88:29.25 2326.8:2850.9 4096 49.59:29.15 3871.1:4880.3 8192 46.09:32.66 6822.9:7825.1 16K 42.90:34.96 11347.1:11767.4 For large message size, 60 secs run remains almost the same. I guess the signal might not play a big role in large message transmission. Shirley -- 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
