On 01/02/2016 12:46, "Andy Zhou" <az...@ovn.org> wrote:
>For the machines I have access to, Reloading the same pointer from
>memory seems to inhibit complier optimization somewhat.
>
>In emc_processing(), using a single packet pointer, instead reloading
>it from memory with packets[i], improves performance by 0.3 Mpps (tested
>with 10G NIC pushing 64 byte packets, with the base line of 12.2 Mpps).
>
>Besides improving performance, this patch should also improves code
>readability.
Nice :-)
>Signed-off-by: Andy Zhou <az...@ovn.org>
Acked-by: Daniele Di Proietto <diproiet...@vmware.com>
One minor nit below
>---
> lib/dpif-netdev.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
>diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
>index 9abb948..c619b86 100644
>--- a/lib/dpif-netdev.c
>+++ b/lib/dpif-netdev.c
>@@ -3301,9 +3301,10 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
>struct dp_packet **packets,
>
> for (i = 0; i < cnt; i++) {
> struct dp_netdev_flow *flow;
>+ struct dp_packet *packet = packets[i];
>
>- if (OVS_UNLIKELY(dp_packet_size(packets[i]) < ETH_HEADER_LEN)) {
>- dp_packet_delete(packets[i]);
>+ if (OVS_UNLIKELY(dp_packet_size(packet) < ETH_HEADER_LEN)) {
>+ dp_packet_delete(packet);
> n_dropped++;
> continue;
> }
>@@ -3316,16 +3317,16 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
>struct dp_packet **packets,
> struct netdev_flow_key *key = &keys[n_missed];
> miniflow_extract(packets[i], &key->mf);
I guess this should be updated also (it's in the next patch, instead)
> key->len = 0; /* Not computed yet. */
>- key->hash = dpif_netdev_packet_get_rss_hash(packets[i],
>&key->mf);
>+ key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf);
>
> flow = emc_lookup(flow_cache, key);
> if (OVS_LIKELY(flow)) {
>- dp_netdev_queue_batches(packets[i], flow, &key->mf, batches,
>+ dp_netdev_queue_batches(packet, flow, &key->mf, batches,
> n_batches);
> } else {
> /* Exact match cache missed. Group missed packets together at
> * the beginning of the 'packets' array. */
>- packets[n_missed++] = packets[i];
>+ packets[n_missed++] = packet;
> }
> }
>
>--
>1.9.1
>
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