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From: Joyce Kong <joyce.kong@arm.com>
To: dev@dpdk.org
Cc: nd@arm.com, Gavin Hu <gavin.hu@arm.com>,
	jerinj@marvell.com, konstantin.ananyev@intel.com,
	chaozhu@linux.vnet.ibm.com, bruce.richardson@intel.com,
	thomas@monjalon.net, hemant.agrawal@nxp.com,
	honnappa.nagarahalli@arm.com
Subject: [dpdk-dev] [PATCH v3 1/3] rwlock: reimplement with atomic builtins
Date: Thu, 14 Mar 2019 21:15:02 +0800	[thread overview]
Message-ID: <1552569304-74817-2-git-send-email-joyce.kong@arm.com> (raw)
Message-ID: <20190314131502.IcrabL03DFha0ChM_4WHKiYalXUWw0lCkCyyF3ghGYA@z> (raw)
In-Reply-To: <1552569304-74817-1-git-send-email-joyce.kong@arm.com>
In-Reply-To: <1544672265-219262-2-git-send-email-joyce.kong@arm.com>

From: Gavin Hu <gavin.hu@arm.com>

The __sync builtin based implementation generates full memory
barriers ('dmb ish') on Arm platforms. Using C11 atomic builtins
to generate one way barriers.

Here is the assembly code of __sync_compare_and_swap builtin.
__sync_bool_compare_and_swap(dst, exp, src);
   0x000000000090f1b0 <+16>:    e0 07 40 f9 ldr x0, [sp, #8]
   0x000000000090f1b4 <+20>:    e1 0f 40 79 ldrh    w1, [sp, #6]
   0x000000000090f1b8 <+24>:    e2 0b 40 79 ldrh    w2, [sp, #4]
   0x000000000090f1bc <+28>:    21 3c 00 12 and w1, w1, #0xffff
   0x000000000090f1c0 <+32>:    03 7c 5f 48 ldxrh   w3, [x0]
   0x000000000090f1c4 <+36>:    7f 00 01 6b cmp w3, w1
   0x000000000090f1c8 <+40>:    61 00 00 54 b.ne    0x90f1d4
<rte_atomic16_cmpset+52>  // b.any
   0x000000000090f1cc <+44>:    02 fc 04 48 stlxrh  w4, w2, [x0]
   0x000000000090f1d0 <+48>:    84 ff ff 35 cbnz    w4, 0x90f1c0
<rte_atomic16_cmpset+32>
   0x000000000090f1d4 <+52>:    bf 3b 03 d5 dmb ish
   0x000000000090f1d8 <+56>:    e0 17 9f 1a cset    w0, eq  // eq = none

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Tested-by: Joyce Kong <joyce.kong@arm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
---
 lib/librte_eal/common/include/generic/rte_rwlock.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/librte_eal/common/include/generic/rte_rwlock.h b/lib/librte_eal/common/include/generic/rte_rwlock.h
index b05d85a..3317a21 100644
--- a/lib/librte_eal/common/include/generic/rte_rwlock.h
+++ b/lib/librte_eal/common/include/generic/rte_rwlock.h
@@ -64,14 +64,14 @@ rte_rwlock_read_lock(rte_rwlock_t *rwl)
 	int success = 0;
 
 	while (success == 0) {
-		x = rwl->cnt;
+		x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
 		/* write lock is held */
 		if (x < 0) {
 			rte_pause();
 			continue;
 		}
-		success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
-					      (uint32_t)x, (uint32_t)(x + 1));
+		success = __atomic_compare_exchange_n(&rwl->cnt, &x, x+1, 1,
+					__ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
 	}
 }
 
@@ -114,7 +114,7 @@ rte_rwlock_read_trylock(rte_rwlock_t *rwl)
 static inline void
 rte_rwlock_read_unlock(rte_rwlock_t *rwl)
 {
-	rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
+	__atomic_fetch_sub(&rwl->cnt, 1, __ATOMIC_RELEASE);
 }
 
 /**
@@ -156,14 +156,14 @@ rte_rwlock_write_lock(rte_rwlock_t *rwl)
 	int success = 0;
 
 	while (success == 0) {
-		x = rwl->cnt;
+		x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
 		/* a lock is held */
 		if (x != 0) {
 			rte_pause();
 			continue;
 		}
-		success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
-					      0, (uint32_t)-1);
+		success = __atomic_compare_exchange_n(&rwl->cnt, &x, -1, 1,
+					__ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
 	}
 }
 
@@ -176,7 +176,7 @@ rte_rwlock_write_lock(rte_rwlock_t *rwl)
 static inline void
 rte_rwlock_write_unlock(rte_rwlock_t *rwl)
 {
-	rte_atomic32_inc((rte_atomic32_t *)(intptr_t)&rwl->cnt);
+	__atomic_store_n(&rwl->cnt, 0, __ATOMIC_RELEASE);
 }
 
 /**
-- 
2.7.4


  parent reply	other threads:[~2019-03-14 13:15 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-13  3:37 [dpdk-dev] [PATCH v1 0/2] reimplement rwlock and add relevant perf test case Joyce Kong
2018-12-13  3:37 ` [dpdk-dev] [PATCH v1 1/2] test/rwlock: add " Joyce Kong
2018-12-19 23:34   ` Ananyev, Konstantin
2018-12-20  1:01     ` Gavin Hu (Arm Technology China)
2018-12-20  1:45       ` Honnappa Nagarahalli
2019-03-14 13:15   ` [dpdk-dev] [PATCH v3 0/3] rwlock: reimplement rwlock with atomic and add relevant " Joyce Kong
2019-03-14 13:15     ` Joyce Kong
2019-03-14 13:15   ` Joyce Kong [this message]
2019-03-14 13:15     ` [dpdk-dev] [PATCH v3 1/3] rwlock: reimplement with atomic builtins Joyce Kong
2019-03-14 15:54     ` Stephen Hemminger
2019-03-14 15:54       ` Stephen Hemminger
2019-03-15  3:04       ` Gavin Hu (Arm Technology China)
2019-03-15  3:04         ` Gavin Hu (Arm Technology China)
2019-03-15 11:41     ` Ananyev, Konstantin
2019-03-15 11:41       ` Ananyev, Konstantin
2019-03-19  8:31       ` Gavin Hu (Arm Technology China)
2019-03-19  8:31         ` Gavin Hu (Arm Technology China)
2019-03-14 13:15   ` [dpdk-dev] [PATCH v3 2/3] test/rwlock: add perf test case on all available cores Joyce Kong
2019-03-14 13:15     ` Joyce Kong
2019-03-14 13:15   ` [dpdk-dev] [PATCH v3 3/3] test/rwlock: amortize the cost of getting time Joyce Kong
2019-03-14 13:15     ` Joyce Kong
2019-03-14 15:02     ` Honnappa Nagarahalli
2019-03-14 15:02       ` Honnappa Nagarahalli
2019-03-20  6:25   ` [dpdk-dev] [PATCH v4 0/3] rwlock: reimplement rwlock with atomic and add relevant perf test case Joyce Kong
2019-03-20  6:25     ` Joyce Kong
2019-03-20  6:25   ` [dpdk-dev] [PATCH v4 1/3] rwlock: reimplement with atomic builtins Joyce Kong
2019-03-20  6:25     ` Joyce Kong
2019-03-21 18:43     ` Ananyev, Konstantin
2019-03-21 18:43       ` Ananyev, Konstantin
2019-03-25  9:18       ` Joyce Kong (Arm Technology China)
2019-03-25  9:18         ` Joyce Kong (Arm Technology China)
2019-03-20  6:25   ` [dpdk-dev] [PATCH v4 2/3] test/rwlock: add perf test case on all available cores Joyce Kong
2019-03-20  6:25     ` Joyce Kong
2019-03-21 18:44     ` Ananyev, Konstantin
2019-03-21 18:44       ` Ananyev, Konstantin
2019-03-20  6:25   ` [dpdk-dev] [PATCH v4 3/3] test/rwlock: amortize the cost of getting time Joyce Kong
2019-03-20  6:25     ` Joyce Kong
2019-03-21 18:44     ` Ananyev, Konstantin
2019-03-21 18:44       ` Ananyev, Konstantin
2019-03-25  9:14   ` [dpdk-dev] [PATCH v5 0/3] rwlock: reimplement rwlock with atomic and add relevant perf test case Joyce Kong
2019-03-25  9:14     ` Joyce Kong
2019-03-28 10:50     ` Thomas Monjalon
2019-03-28 10:50       ` Thomas Monjalon
2019-04-16 14:57     ` Kevin Traynor
2019-04-16 14:57       ` Kevin Traynor
2019-03-25  9:14   ` [dpdk-dev] [PATCH v5 1/3] rwlock: reimplement with atomic builtins Joyce Kong
2019-03-25  9:14     ` Joyce Kong
2019-03-25  9:14   ` [dpdk-dev] [PATCH v5 2/3] test/rwlock: add perf test case on all available cores Joyce Kong
2019-03-25  9:14     ` Joyce Kong
2019-03-25  9:14   ` [dpdk-dev] [PATCH v5 3/3] test/rwlock: amortize the cost of getting time Joyce Kong
2019-03-25  9:14     ` Joyce Kong
2018-12-13  3:37 ` [dpdk-dev] [PATCH v1 2/2] rwlock: reimplement with __atomic builtins Joyce Kong
2018-12-19 23:50   ` Ananyev, Konstantin
2018-12-13  5:27 ` [dpdk-dev] [PATCH v1 0/2] reimplement rwlock and add relevant perf test case Stephen Hemminger
2018-12-14  1:30   ` Gavin Hu (Arm Technology China)
2018-12-17  5:16     ` Honnappa Nagarahalli
2018-12-19 20:37       ` Thomas Monjalon

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