diff mbox series

mbuf: use c11 atomics for refcnt operations

Message ID 1591871178-12542-1-git-send-email-phil.yang@arm.com (mailing list archive)
State Superseded, archived
Delegated to: David Marchand
Headers show
Series mbuf: use c11 atomics for refcnt operations | expand

Checks

Context Check Description
ci/Intel-compilation success Compilation OK
ci/iol-testing success Testing PASS
ci/travis-robot warning Travis build: failed
ci/iol-mellanox-Performance success Performance Testing PASS
ci/iol-nxp-Performance success Performance Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-broadcom-Performance success Performance Testing PASS
ci/checkpatch success coding style OK

Commit Message

Phil Yang June 11, 2020, 10:26 a.m. UTC
Use c11 atomics with explicit ordering instead of rte_atomic ops which
enforce unnecessary barriers on aarch64.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
 lib/librte_mbuf/rte_mbuf.c      |  1 -
 lib/librte_mbuf/rte_mbuf.h      | 19 ++++++++++---------
 lib/librte_mbuf/rte_mbuf_core.h | 11 +++--------
 3 files changed, 13 insertions(+), 18 deletions(-)

Comments

David Marchand July 3, 2020, 3:38 p.m. UTC | #1
On Thu, Jun 11, 2020 at 12:26 PM Phil Yang <phil.yang@arm.com> wrote:
>
> Use c11 atomics with explicit ordering instead of rte_atomic ops which
> enforce unnecessary barriers on aarch64.
>
> Signed-off-by: Phil Yang <phil.yang@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>

I did not look at the details, but this patch is refused by the ABI
check in Travis.
Phil Yang July 6, 2020, 8:03 a.m. UTC | #2
> -----Original Message-----
> From: David Marchand <david.marchand@redhat.com>
> Sent: Friday, July 3, 2020 11:39 PM
> To: Phil Yang <Phil.Yang@arm.com>
> Cc: dev <dev@dpdk.org>; Olivier Matz <olivier.matz@6wind.com>; David
> Christensen <drc@linux.vnet.ibm.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>; nd <nd@arm.com>
> Subject: Re: [dpdk-dev] [PATCH] mbuf: use c11 atomics for refcnt operations
> 
> On Thu, Jun 11, 2020 at 12:26 PM Phil Yang <phil.yang@arm.com> wrote:
> >
> > Use c11 atomics with explicit ordering instead of rte_atomic ops which
> > enforce unnecessary barriers on aarch64.
> >
> > Signed-off-by: Phil Yang <phil.yang@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> 
> I did not look at the details, but this patch is refused by the ABI
> check in Travis.

Thanks, David.
The ABI issue is the name of 'rte_mbuf_ext_shared_info::refcnt_atomic' changed to 'rte_mbuf_ext_shared_info::refcnt' at rte_mbuf_core.h.
I made this change just to simplify the name of the variable.

Revert the 'rte_mbuf_ext_shared_info::refcnt' to refcnt_atomic can fix this issue.
I will update it in v2.

Thanks,
Phil

> 
> 
> --
> David Marchand
diff mbox series

Patch

diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 220eb2f..e41b153 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..86270a7 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 (uint16_t)(__atomic_add_fetch((int16_t *)&m->refcnt, 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 (uint16_t)(__atomic_add_fetch((int16_t *)&shinfo->refcnt, 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((int *)&shinfo->refcnt, -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 b9a59c8..12cc38a 100644
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -16,7 +16,6 @@ 
 
 #include <stdint.h>
 #include <rte_compat.h>
-#include <generic/rte_atomic.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -493,12 +492,8 @@  struct rte_mbuf {
 	 * or non-atomic) is controlled by the CONFIG_RTE_MBUF_REFCNT_ATOMIC
 	 * config option.
 	 */
-	RTE_STD_C11
-	union {
-		rte_atomic16_t refcnt_atomic; /**< Atomically accessed refcnt */
-		/** Non-atomically accessed refcnt */
-		uint16_t refcnt;
-	};
+	uint16_t refcnt;
+
 	uint16_t nb_segs;         /**< Number of segments. */
 
 	/** Input port (16 bits to support more than 256 virtual ports).
@@ -676,7 +671,7 @@  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 */
+	uint16_t refcnt;                     /**< Atomically accessed refcnt */
 };
 
 /**< Maximum number of nb_segs allowed. */