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From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org
Cc: "Bruce Richardson" <bruce.richardson@intel.com>,
	"Morten Brørup" <mb@smartsharesystems.com>,
	"Jerin Jacob" <jerinj@marvell.com>
Subject: [PATCH v2] eventdev: ensure 16-byte alignment for events
Date: Fri,  6 Oct 2023 10:37:33 +0100	[thread overview]
Message-ID: <20231006093733.73420-1-bruce.richardson@intel.com> (raw)
In-Reply-To: <20231005115101.12276-1-bruce.richardson@intel.com>

The event structure in DPDK is 16-bytes in size, and events are
regularly passed as parameters directly rather than being passed as
pointers. To help compiler optimize correctly, we can explicitly request
16-byte alignment for events, which means that we should be able
to do aligned vector loads/stores (e.g. with SSE or Neon) when working
with those events.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
---
 doc/guides/rel_notes/release_23_11.rst | 4 ++++
 lib/eventdev/rte_eventdev.h            | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/doc/guides/rel_notes/release_23_11.rst b/doc/guides/rel_notes/release_23_11.rst
index 261594aacc..48c19ae52a 100644
--- a/doc/guides/rel_notes/release_23_11.rst
+++ b/doc/guides/rel_notes/release_23_11.rst
@@ -158,6 +158,10 @@ ABI Changes
    Also, make sure to start the actual text at the margin.
    =======================================================
 
+* The ``rte_event`` structure, used by eventdev library and DPDK "event" class drivers,
+  is now 16-byte aligned, as well as being 16-bytes in size.
+  In previous releases, the structure only required 8-byte alignement.
+
 
 Known Issues
 ------------
diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
index 2ea98302b8..5b7c5b3399 100644
--- a/lib/eventdev/rte_eventdev.h
+++ b/lib/eventdev/rte_eventdev.h
@@ -1284,6 +1284,8 @@ struct rte_event_vector {
 /**
  * The generic *rte_event* structure to hold the event attributes
  * for dequeue and enqueue operation
+ *
+ * This structure must be kept at 16-bytes in size, and has 16-byte alignment.
  */
 struct rte_event {
 	/** WORD0 */
@@ -1356,7 +1358,9 @@ struct rte_event {
 		struct rte_event_vector *vec;
 		/**< Event vector pointer. */
 	};
-};
+} __rte_aligned(16);
+
+_Static_assert(sizeof(struct rte_event) == 16, "Event structure size is not 16-bytes in size");
 
 /* Ethdev Rx adapter capability bitmap flags */
 #define RTE_EVENT_ETH_RX_ADAPTER_CAP_INTERNAL_PORT	0x1
-- 
2.39.2


  parent reply	other threads:[~2023-10-06  9:38 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-05 11:51 [RFC PATCH] " Bruce Richardson
2023-10-05 12:06 ` Bruce Richardson
2023-10-05 13:11   ` Jerin Jacob
2023-10-05 13:15     ` Bruce Richardson
2023-10-06  7:19       ` Jerin Jacob
2023-10-05 12:12 ` Morten Brørup
2023-10-05 13:02   ` Bruce Richardson
2023-10-06  9:37 ` Bruce Richardson [this message]
2023-10-06  9:45 ` [PATCH v3] " Bruce Richardson
2023-10-06 10:13   ` Morten Brørup
2023-10-06 10:16     ` Jerin Jacob
2023-10-06 10:19       ` Bruce Richardson
2023-10-06 10:24         ` Jerin Jacob
2023-10-06 10:27           ` Bruce Richardson
2023-10-06 10:16     ` Bruce Richardson
2023-10-06 10:35       ` Morten Brørup
2023-10-06 10:44         ` Bruce Richardson
2023-10-06 10:29 ` [PATCH v4] " Bruce Richardson
2023-11-12  0:01   ` Stephen Hemminger
2023-11-12  8:30     ` Morten Brørup
2023-11-12 23:31       ` Stephen Hemminger
2023-11-13  7:58         ` Morten Brørup
2024-01-19 21:05           ` Tyler Retzlaff
2023-10-06 12:15 ` [RFC PATCH] " Mattias Rönnblom
2023-10-06 12:19   ` Bruce Richardson
2023-10-06 12:29     ` Mattias Rönnblom
2024-01-19 22:30   ` Stephen Hemminger

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