Messages in this thread |  | | | Subject | [PATCH V3 0/8] macvtap/vhost TX zero copy support | | From | Shirley Ma <> | | Date | Wed, 20 Apr 2011 12:36:56 -0700 |
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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:
1/8: Add a new sock zero-copy flag, SOCK_ZEROCOPY;
2/8: Add a new device flag, NETIF_F_ZEROCOPY for lower level device support zero-copy;
3/8: Add a new struct skb_ubuf_info in skb_share_info for userspace buffers release callback when lower device DMA has done for that skb;
4/8: 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.
5/8: Add macvtap zero-copy in lower device when sending packet is greater than 128 bytes.
6/8: Add Chelsio 10Gb NIC to zero copy feature flag
7/8: Add Intel 10Gb NIC zero copy feature flag
8/8: Add Emulex 10Gb NIC zero copy feature flag
The patchset is built against most recent linux 2.6.git. It has passed netperf/netserver multiple streams stress test on above NICs.
The single stream test results from 2.6.37 kernel on Chelsio:
64K message size: copy_from_user dropped from 40% to 5%; vhost thread cpu utilization dropped from 76% to 28%
I am collecting more test results against 2.6.39-rc3 kernel and will provide the test matrix later.
Thanks Shirley
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