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mbuf: use C11 atomic builtins for refcnt

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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>
This commit is contained in:
Phil Yang 2020-07-17 12:36:50 +08:00 committed by David Marchand
parent cf43d9d04b
commit db48bae253
4 changed files with 19 additions and 11 deletions
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4
devtools/libabigail.abignore
View file

@ -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

1
lib/librte_mbuf/rte_mbuf.c
View file

@ -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>

19
lib/librte_mbuf/rte_mbuf.h
View file

@ -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. */

6
lib/librte_mbuf/rte_mbuf_core.h
View file

@ -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. */