On 2018/10/17 17:39, Jason Wang wrote: > > On 2018/10/17 下午5:27, jiangyiwen wrote: >> On 2018/10/15 14:12, jiangyiwen wrote: >>> On 2018/10/15 10:33, Jason Wang wrote: >>>> >>>> On 2018年10月15日 09:43, jiangyiwen wrote: >>>>> Hi Stefan & All: >>>>> >>>>> Now I find vhost-vsock has two performance problems even if it >>>>> is not designed for performance. >>>>> >>>>> First, I think vhost-vsock should faster than vhost-net because it >>>>> is no TCP/IP stack, but the real test result vhost-net is 5~10 >>>>> times than vhost-vsock, currently I am looking for the reason. >>>> TCP/IP is not a must for vhost-net. >>>> >>>> How do you test and compare the performance? >>>> >>>> Thanks >>>> >>> I test the performance used my test tool, like follows: >>> >>> Server Client >>> socket() >>> bind() >>> listen() >>> >>> socket(AF_VSOCK) or socket(AF_INET) >>> Accept() <-------------->connect() >>> *======Start Record Time======* >>> Call syscall sendfile() >>> Recv() >>> Send end >>> Receive end >>> Send(file_size) >>> Recv(file_size) >>> *======End Record Time======* >>> >>> The test result, vhost-vsock is about 500MB/s, and vhost-net is about >>> 2500MB/s. >>> >>> By the way, vhost-net use single queue. >>> >>> Thanks. >>> >>>>> Second, vhost-vsock only supports two vqs(tx and rx), that means >>>>> if multiple sockets in the guest will use the same vq to transmit >>>>> the message and get the response. So if there are multiple applications >>>>> in the guest, we should support "Multiqueue" feature for Virtio-vsock. >>>>> >>>>> Stefan, have you encountered these problems? >>>>> >>>>> Thanks, >>>>> Yiwen. >>>>> >>>> >>>> . >>>> >>> >> Hi Jason and Stefan, >> >> Maybe I find the reason of bad performance. >> >> I found pkt_len is limited to VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE(4K), >> it will cause the bandwidth is limited to 500~600MB/s. And once I >> increase to 64k, it can improve about 3 times(~1500MB/s). > > > Looks like the value was chosen for a balance between rx buffer size and > performance. Allocating 64K always even for small packet is kind of waste and > stress for guest memory. Virito-net try to avoid this by inventing the merge > able rx buffer which allows big packet to be scattered in into different > buffers. We can reuse this idea or revisit the idea of using > virtio-net/vhost-net as a transport of vsock. > > What interesting is the performance is still behind vhost-net. > > Thanks >
Actually I don't understand why pkt_len is limited to VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE in virtio_transport_send_pkt_info(), while I think it should used VIRTIO_VSOCK_MAX_PKT_BUF_SIZE instead. Thanks. >> >> By the way, I send to 64K in application once, and I don't use >> sg_init_one and rewrite function to packet sg list because pkt_len >> include multiple pages. >> >> Thanks, >> Yiwen. >> >>> _______________________________________________ >>> Virtualization mailing list >>> Virtualization@lists.linux-foundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization >>> >> > > . > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
