[dpdk-dev,v4] mbuf: fix mbuf free performance with non atomic refcnt
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Commit Message
Oliver, Looks great.
Thanks,
Hanoh
-----Original Message-----
From: Olivier Matz [mailto:olivier.matz@6wind.com]
Sent: Friday, December 08, 2017 5:47 PM
To: dev@dpdk.org; Hanoch Haim (hhaim)
Cc: matvejchikov@gmail.com; konstantin.ananyev@intel.com
Subject: [PATCH v4] mbuf: fix mbuf free performance with non atomic refcnt
When RTE_MBUF_REFCNT_ATOMIC=n, the decrement of the mbuf reference counter uses an atomic operation. This is not necessary and impacts the performance (seen with TRex traffic generator).
We cannot replace rte_atomic16_add_return() by rte_mbuf_refcnt_update() because it would add an additional check.
Solves this by introducing __rte_mbuf_refcnt_update(), which updates the reference counter without doing anything else.
Fixes: 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool")
Suggested-by: Hanoch Haim <hhaim@cisco.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
Hanoh,
The following patch implements what was discussed in the thread.
Are you ok with it?
Thanks,
Olivier
lib/librte_mbuf/rte_mbuf.h | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
}
- return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value));
+ return __rte_mbuf_refcnt_update(m, value);
}
#else /* ! RTE_MBUF_REFCNT_ATOMIC */
+/* internal */
+static inline uint16_t
+__rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) {
+ m->refcnt = (uint16_t)(m->refcnt + value);
+ return m->refcnt;
+}
+
/**
* Adds given value to an mbuf's refcnt and returns its new value.
*/
static inline uint16_t
rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) {
- m->refcnt = (uint16_t)(m->refcnt + value);
- return m->refcnt;
+ return __rte_mbuf_refcnt_update(m, value);
}
/**
@@ -1364,8 +1378,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
return m;
- } else if (rte_atomic16_add_return(&m->refcnt_atomic, -1) == 0) {
-
+ } else if (__rte_mbuf_refcnt_update(m, -1) == 0) {
if (RTE_MBUF_INDIRECT(m))
rte_pktmbuf_detach(m);
--
2.11.0
@@ -764,6 +764,13 @@ rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
rte_atomic16_set(&m->refcnt_atomic, new_value); }
+/* 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));
+}
+
/**
* Adds given value to an mbuf's refcnt and returns its new value.
* @param m
@@ -788,19 +795,26 @@ rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value)
return 1 + value;