On Wed, Apr 20, 2011 at 3:36 PM, Shirley Ma <mashirle@xxxxxxxxxx> wrote: > 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 Why are only these 3 drivers getting support? As far as I can tell, the only requirement is HIGHDMA. If this is the case, is there really a need for an additional flag to support this? If you can key off of HIGHDMA, all devices that support this would get the benefit. > 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 > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- 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
