[dpdk-dev] [PATCH v7 4/7] ticketlock: use new API to reduce contention on aarch64

Gavin Hu gavin.hu at arm.com
Fri Sep 27 07:41:41 CEST 2019


While using ticket lock, cores repeatedly poll the lock variable.
This is replaced by rte_wait_until_equal API.

Running ticketlock_autotest on ThunderX2, Ampere eMAG80, and Arm N1SDP[1],
there were variances between runs, but no notable performance gain or
degradation were seen with and without this patch.

[1] https://community.arm.com/developer/tools-software/oss-platforms/w/\
docs/440/neoverse-n1-sdp

Signed-off-by: Gavin Hu <gavin.hu at arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
Tested-by: Phil Yang <phil.yang at arm.com>
Tested-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
Reviewed-by: Jerin Jacob <jerinj at marvell.com>
---
 lib/librte_eal/common/include/generic/rte_ticketlock.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/librte_eal/common/include/generic/rte_ticketlock.h b/lib/librte_eal/common/include/generic/rte_ticketlock.h
index d9bec87..232bbe9 100644
--- a/lib/librte_eal/common/include/generic/rte_ticketlock.h
+++ b/lib/librte_eal/common/include/generic/rte_ticketlock.h
@@ -66,8 +66,7 @@ static inline void
 rte_ticketlock_lock(rte_ticketlock_t *tl)
 {
 	uint16_t me = __atomic_fetch_add(&tl->s.next, 1, __ATOMIC_RELAXED);
-	while (__atomic_load_n(&tl->s.current, __ATOMIC_ACQUIRE) != me)
-		rte_pause();
+	rte_wait_until_equal_acquire_16(&tl->s.current, me);
 }
 
 /**
-- 
2.7.4



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