Re: [dpdk-dev] [PATCH 0/3] [RFC] vhost: micro vhost optimization

[Rich Lane <rich.lane@bigswitch.com>]

I see a significant performance improvement with these patches, around 5%
at 64 bytes.

The one patch that didn't give any performance boost for me was "vhost:
arrange virtio_net fields for better cache sharing".

Tested-by: Rich Lane <rich.lane@bigswitch.com>

On Mon, May 2, 2016 at 5:46 PM, Yuanhan Liu <yuanhan.liu@linux.intel.com>
wrote:

> Here is a small patch set does the micro optimization, which brings about
> 10% performance boost in my 64B packet testing, with the following topo:
>
>     pkt generator <----> NIC <-----> Virtio NIC
>
> Patch 1 pre updates the used ring and update them in batch. It should be
> feasible from my understanding: there will be no issue, guest driver will
> not start processing them as far as we haven't updated the "used->idx"
> yet. I could miss something though.
>
> Patch 2 saves one check for small packets (that can be hold in one desc
> buf and mbuf).
>
> Patch 3 moves several frequently used fields into one cache line, for
> better cache sharing.
>
> Note that this patch set is based on my latest vhost ABI refactoring
> patchset.
>
>
> ---
> Yuanhan Liu (3):
>   vhost: pre update used ring for Tx and Rx
>   vhost: optimize dequeue for small packets
>   vhost: arrange virtio_net fields for better cache sharing
>
>  lib/librte_vhost/vhost-net.h  |   8 +--
>  lib/librte_vhost/vhost_rxtx.c | 110
> ++++++++++++++++++++++++------------------
>  2 files changed, 68 insertions(+), 50 deletions(-)
>
> --
> 1.9.0
>
>