diff mbox series

[v5,1/2] mbuf: use C11 atomic builtins for refcnt operations

Message ID 1594960611-19470-1-git-send-email-phil.yang@arm.com (mailing list archive)
State Accepted, archived
Delegated to: David Marchand
Headers
Series [v5,1/2] mbuf: use C11 atomic builtins for refcnt operations |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/iol-broadcom-Performance success Performance Testing PASS
ci/Intel-compilation success Compilation OK
ci/iol-mellanox-Performance success Performance Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-testing success Testing PASS

Commit Message

Phil Yang July 17, 2020, 4:36 a.m. UTC 
  Use C11 atomic builtins with explicit ordering instead of rte_atomic
ops which enforce unnecessary barriers on aarch64.

Suggested-by: Olivier Matz <olivier.matz@6wind.com>
Suggested-by: Dodji Seketeli <dodji@redhat.com>
Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
---
v5:
1. Change built-ins to builtins.
2. Ignore updates of rte_mbuf_ext_shared_info refcnt_atomic in ABI
checker.

v4:
1. Add union for refcnt_atomic and refcnt in rte_mbuf_ext_shared_info
to avoid ABI breakage. (Olivier)
2. Add notice of refcnt_atomic deprecation. (Honnappa)

v3:
1.Fix ABI breakage.
2.Simplify data type cast.

v2:
Fix ABI issue: revert the rte_mbuf_ext_shared_info struct refcnt field
to refcnt_atomic.

 devtools/libabigail.abignore    |  4 ++++
 lib/librte_mbuf/rte_mbuf.c      |  1 -
 lib/librte_mbuf/rte_mbuf.h      | 19 ++++++++++---------
 lib/librte_mbuf/rte_mbuf_core.h |  6 +++++-
 4 files changed, 19 insertions(+), 11 deletions(-)

Comments

David Marchand July 21, 2020, 8:37 a.m. UTC | #1 
On Fri, Jul 17, 2020 at 6:37 AM Phil Yang <phil.yang@arm.com> wrote:
>
> Use C11 atomic builtins with explicit ordering instead of rte_atomic
> ops which enforce unnecessary barriers on aarch64.
>
> Suggested-by: Olivier Matz <olivier.matz@6wind.com>
> Suggested-by: Dodji Seketeli <dodji@redhat.com>
> Signed-off-by: Phil Yang <phil.yang@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> Acked-by: Olivier Matz <olivier.matz@6wind.com>

Series applied, thanks Phil.
diff mbox series

Patch

diff --git a/devtools/libabigail.abignore b/devtools/libabigail.abignore
index daa4631..9fea822 100644
--- a/devtools/libabigail.abignore
+++ b/devtools/libabigail.abignore
@@ -52,6 +52,10 @@ 
 [suppress_type]
         type_kind = struct
         name = rte_epoll_event
+; Ignore updates of rte_mbuf_ext_shared_info refcnt_atomic
+[suppress_type]
+        name = rte_mbuf_ext_shared_info
+        has_data_member_inserted_between = {offset_of(refcnt_atomic), offset_of(refcnt_atomic)}
 
 ;;;;;;;;;;;;;;;;;;;;;;
 ; Temporary exceptions till DPDK 20.11
diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index ae91ae2..8a456e5 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -22,7 +22,6 @@ 
 #include <rte_eal.h>
 #include <rte_per_lcore.h>
 #include <rte_lcore.h>
-#include <rte_atomic.h>
 #include <rte_branch_prediction.h>
 #include <rte_mempool.h>
 #include <rte_mbuf.h>
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index f8e492e..7259575 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -37,7 +37,6 @@ 
 #include <rte_config.h>
 #include <rte_mempool.h>
 #include <rte_memory.h>
-#include <rte_atomic.h>
 #include <rte_prefetch.h>
 #include <rte_branch_prediction.h>
 #include <rte_byteorder.h>
@@ -365,7 +364,7 @@  rte_pktmbuf_priv_flags(struct rte_mempool *mp)
 static inline uint16_t
 rte_mbuf_refcnt_read(const struct rte_mbuf *m)
 {
-	return (uint16_t)(rte_atomic16_read(&m->refcnt_atomic));
+	return __atomic_load_n(&m->refcnt, __ATOMIC_RELAXED);
 }
 
 /**
@@ -378,14 +377,15 @@  rte_mbuf_refcnt_read(const struct rte_mbuf *m)
 static inline void
 rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
 {
-	rte_atomic16_set(&m->refcnt_atomic, (int16_t)new_value);
+	__atomic_store_n(&m->refcnt, new_value, __ATOMIC_RELAXED);
 }
 
 /* internal */
 static inline uint16_t
 __rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value)
 {
-	return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value));
+	return __atomic_add_fetch(&m->refcnt, (uint16_t)value,
+				 __ATOMIC_ACQ_REL);
 }
 
 /**
@@ -466,7 +466,7 @@  rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
 static inline uint16_t
 rte_mbuf_ext_refcnt_read(const struct rte_mbuf_ext_shared_info *shinfo)
 {
-	return (uint16_t)(rte_atomic16_read(&shinfo->refcnt_atomic));
+	return __atomic_load_n(&shinfo->refcnt, __ATOMIC_RELAXED);
 }
 
 /**
@@ -481,7 +481,7 @@  static inline void
 rte_mbuf_ext_refcnt_set(struct rte_mbuf_ext_shared_info *shinfo,
 	uint16_t new_value)
 {
-	rte_atomic16_set(&shinfo->refcnt_atomic, (int16_t)new_value);
+	__atomic_store_n(&shinfo->refcnt, new_value, __ATOMIC_RELAXED);
 }
 
 /**
@@ -505,7 +505,8 @@  rte_mbuf_ext_refcnt_update(struct rte_mbuf_ext_shared_info *shinfo,
 		return (uint16_t)value;
 	}
 
-	return (uint16_t)rte_atomic16_add_return(&shinfo->refcnt_atomic, value);
+	return __atomic_add_fetch(&shinfo->refcnt, (uint16_t)value,
+				 __ATOMIC_ACQ_REL);
 }
 
 /** Mbuf prefetch */
@@ -1304,8 +1305,8 @@  static inline int __rte_pktmbuf_pinned_extbuf_decref(struct rte_mbuf *m)
 	 * Direct usage of add primitive to avoid
 	 * duplication of comparing with one.
 	 */
-	if (likely(rte_atomic16_add_return
-			(&shinfo->refcnt_atomic, -1)))
+	if (likely(__atomic_add_fetch(&shinfo->refcnt, (uint16_t)-1,
+				     __ATOMIC_ACQ_REL)))
 		return 1;
 
 	/* Reinitialize counter before mbuf freeing. */
diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
index 16600f1..8cd7137 100644
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -679,7 +679,11 @@  typedef void (*rte_mbuf_extbuf_free_callback_t)(void *addr, void *opaque);
 struct rte_mbuf_ext_shared_info {
 	rte_mbuf_extbuf_free_callback_t free_cb; /**< Free callback function */
 	void *fcb_opaque;                        /**< Free callback argument */
-	rte_atomic16_t refcnt_atomic;        /**< Atomically accessed refcnt */
+	RTE_STD_C11
+	union {
+		rte_atomic16_t refcnt_atomic; /**< Atomically accessed refcnt */
+		uint16_t refcnt;
+	};
 };
 
 /**< Maximum number of nb_segs allowed. */