Applied to dpdk-next-virtio.
And thanks for testing and reviewing.
--yliu
On Fri, Oct 14, 2016 at 05:34:31PM +0800, Yuanhan Liu wrote:
> This is a new set of patches to optimize the mergeable Rx code path.
> No refactoring (rewrite) was made this time. It just applies some
> findings from Zhihong (kudos to him!) that could improve the mergeable
> Rx path on the old code.
>
> The two major factors that could improve the performance greatly are:
>
> - copy virtio header together with packet data. This could remove
> the buubbles between the two copy to optimize the cache access.
>
> This is implemented in patch 2 "vhost: optimize cache access"
>
> - shadow used ring update and update them at once
>
> The basic idea is to update used ring in a local buffer and flush
> them to the virtio used ring at once in the end. Again, this is
> for optimizing the cache access.
>
> This is implemented in patch 5 "vhost: shadow used ring update"
>
> The two optimizations could yield 40+% performance in micro testing
> and 20+% in PVP case testing with 64B packet size.
>
> Besides that, there are some tiny optimizations, such as prefetch
> avail ring (patch 6) and retrieve avail head once (patch 7).
>
> Note: the shadow used ring tech could also be applied to the non-mrg
> Rx path (and even the dequeu) path. I didn't do that for two reasons:
>
> - we already update used ring in batch in both path: it's not shadowed
> first though.
>
> - it's a bit too late too make many changes at this stage: RC1 is out.
>
> Please help testing.
>
> Thanks.
>
> --yliu
>
> Cc: Jianbo Liu <jianbo.liu at linaro.org>
> ---
> Yuanhan Liu (4):
> vhost: simplify mergeable Rx vring reservation
> vhost: use last avail idx for avail ring reservation
> vhost: prefetch avail ring
> vhost: retrieve avail head once
>
> Zhihong Wang (3):
> vhost: remove useless volatile
> vhost: optimize cache access
> vhost: shadow used ring update
>
> lib/librte_vhost/vhost.c | 13 ++-
> lib/librte_vhost/vhost.h | 5 +-
> lib/librte_vhost/vhost_user.c | 23 +++--
> lib/librte_vhost/virtio_net.c | 193
> +++++++++++++++++++++++++-----------------
> 4 files changed, 149 insertions(+), 85 deletions(-)
>
> --
> 1.9.0
