[dpdk-dev] [PATCH] ethdev: fix a regression due to cache alignment issue

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

Prior to "ethdev: add port ownership" change, the fast
path structure struct rte_eth_dev->data was cache aligned
due to the fact that eth_dev_data was allocated from
rte_malloc with cache aligned attribute.
"ethdev: add port ownership" change set introduced a
rte_eth_dev_shared_data container for port ownership change,
This resulted in rte_eth_dev->data memory as cache unaligned.
Added a compiler alignment attribute to make sure
rte_eth_dev->data always cache aligned and hence compiler
can load/store the elements in struct rte_eth_dev_data
as naturally aligned.

Some platform like thunderx + l3fwd showed 1% regression in
the performance with the offending changeset.

Fixes: 5b7ba31148a8 ("ethdev: add port ownership")

Cc: Matan Azrad <matan@mellanox.com>
Cc: Thomas Monjalon <thomas@monjalon.net>
Cc: Konstantin Ananyev <konstantin.ananyev@intel.com>

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
---
 lib/librte_ether/rte_ethdev_core.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/librte_ether/rte_ethdev_core.h b/lib/librte_ether/rte_ethdev_core.h
index 315b31723..e5681e466 100644
--- a/lib/librte_ether/rte_ethdev_core.h
+++ b/lib/librte_ether/rte_ethdev_core.h
@@ -601,7 +601,7 @@ struct rte_eth_dev_data {
 	struct rte_vlan_filter_conf vlan_filter_conf;
 	/**< VLAN filter configuration. */
 	struct rte_eth_dev_owner owner; /**< The port owner. */
-};
+} __rte_cache_aligned;
 
 /**
  * @internal
-- 
2.16.1