Messages in this thread | | | Subject | [RFC PATCH V2 0/5] macvtap TX zero copy between guest and host kernel | From | Shirley Ma <> | Date | Fri, 10 Dec 2010 01:51:31 -0800 |
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This patchset add supports for TX zero-copy between guest and host kernel through vhost. It significantly reduces CPU utilization on the local host on which the guest is located (It reduced 30-50% CPU usage for vhost thread for single stream test). The patchset is based on previous submission and comments from the community regarding when/how to handle guest kernel buffers to be released. This is the simplest approach I can think of after comparing with several other solutions.
This patchset includes:
1. Induce a new sock zero-copy flag, SOCK_ZEROCOPY;
2. Induce a new device flag, NETIF_F_ZEROCOPY for device can support zero-copy;
3. Add a new struct skb_ubuf_info in skb_share_info for userspace buffers release callback when device DMA has done for that skb;
4. Add vhost zero-copy callback in vhost when skb last refcnt is gone; add vhost_zerocopy_add_used_and_signal to notify guest to release TX skb buffers.
5. Add macvtap zero-copy in lower device when sending packet is greater than 128 bytes.
The patchset has passed netperf/netserver test on Chelsio, and continuing test on other 10GbE NICs, like Intel ixgbe, Mellanox mlx4... I will provide guest to host, host to guest performance data next week.
However when running stress test, vhost & virtio_net seems out of sync, and virito_net interrupt was disabled somehow, and it stopped to send any packet. This problem has bothered me for a long long time, I will continue to look at this.
Please review this.
Thanks Shirley
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