Acked-by: Ethan Jackson <et...@nicira.com>
One question I had for a future patch. Have you considered
prefetching more packets at once? I.E. 4 at a time or something?
That's how these things are typically written, though I don't know if
it would actually affect things.
Merged.
Ethan
On Mon, Jun 15, 2015 at 11:06 AM, Daniele Di Proietto
<diproiet...@vmware.com> wrote:
> It appears that miniflow_extract() in emc_processing() spends a lot of
> cycles waiting for the packet's data to be read.
>
> Prefetching the next packet's data while parsing removes this delay.
> For a single flow pipeline the throughput improves by ~10%. With a
> more realistic pipeline the change has a much smaller effect (~0.5%
> improvement)
>
> Signed-off-by: Daniele Di Proietto <diproiet...@vmware.com>
> ---
> lib/dpif-netdev.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 5b82c8b..f13169c 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -3150,6 +3150,11 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
> struct dp_packet **packets,
> continue;
> }
>
> + if (i != cnt - 1) {
> + /* Prefetch next packet data */
> + OVS_PREFETCH(dp_packet_data(packets[i+1]));
> + }
> +
> miniflow_extract(packets[i], &key.mf);
> key.len = 0; /* Not computed yet. */
> key.hash = dpif_netdev_packet_get_rss_hash(packets[i], &key.mf);
> --
> 2.1.4
>
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