[1/2] lib/ethdev: replace full barrier with relaxed barrier

Message ID 20201002000711.41511-1-honnappa.nagarahalli@arm.com
State Superseded
Headers show
Series
  • [1/2] lib/ethdev: replace full barrier with relaxed barrier
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Commit Message

Honnappa Nagarahalli Oct. 2, 2020, 12:07 a.m.
From: Phil Yang <phil.yang@arm.com>


While registering the call back functions full write barrier
can be replaced with one-way write barrier.

Signed-off-by: Phil Yang <phil.yang@arm.com>

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>

---
 lib/librte_ethdev/rte_ethdev.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

-- 
2.17.1

Comments

Ferruh Yigit Oct. 13, 2020, 10:30 a.m. | #1
On 10/2/2020 1:07 AM, Honnappa Nagarahalli wrote:
> From: Phil Yang <phil.yang@arm.com>

> 

> While registering the call back functions full write barrier

> can be replaced with one-way write barrier.

> 

> Signed-off-by: Phil Yang <phil.yang@arm.com>

> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>


+Konstantin & Jerin,

Can you please help reviewing this patch?

> ---

>   lib/librte_ethdev/rte_ethdev.c | 9 ++++++---

>   1 file changed, 6 insertions(+), 3 deletions(-)

> 

> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c

> index 7858ad5f1..59a41c07f 100644

> --- a/lib/librte_ethdev/rte_ethdev.c

> +++ b/lib/librte_ethdev/rte_ethdev.c

> @@ -26,7 +26,6 @@

>   #include <rte_eal.h>

>   #include <rte_per_lcore.h>

>   #include <rte_lcore.h>

> -#include <rte_atomic.h>

>   #include <rte_branch_prediction.h>

>   #include <rte_common.h>

>   #include <rte_mempool.h>

> @@ -4527,8 +4526,12 @@ rte_eth_add_first_rx_callback(uint16_t port_id, uint16_t queue_id,

>   	rte_spinlock_lock(&rte_eth_rx_cb_lock);

>   	/* Add the callbacks at first position */

>   	cb->next = rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];

> -	rte_smp_wmb();

> -	rte_eth_devices[port_id].post_rx_burst_cbs[queue_id] = cb;

> +	/* Stores to cb->fn, cb->param and cb->next should complete before

> +	 * cb is visible to data plane threads.

> +	 */

> +	__atomic_store_n(

> +		&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],

> +		cb, __ATOMIC_RELEASE);

>   	rte_spinlock_unlock(&rte_eth_rx_cb_lock);

>   

>   	return cb;

>
Ananyev, Konstantin Oct. 13, 2020, 2:24 p.m. | #2
> From: Phil Yang <phil.yang@arm.com>

> 

> While registering the call back functions full write barrier

> can be replaced with one-way write barrier.

> 

> Signed-off-by: Phil Yang <phil.yang@arm.com>

> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>

> ---

>  lib/librte_ethdev/rte_ethdev.c | 9 ++++++---

>  1 file changed, 6 insertions(+), 3 deletions(-)

> 

> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c

> index 7858ad5f1..59a41c07f 100644

> --- a/lib/librte_ethdev/rte_ethdev.c

> +++ b/lib/librte_ethdev/rte_ethdev.c

> @@ -26,7 +26,6 @@

>  #include <rte_eal.h>

>  #include <rte_per_lcore.h>

>  #include <rte_lcore.h>

> -#include <rte_atomic.h>

>  #include <rte_branch_prediction.h>

>  #include <rte_common.h>

>  #include <rte_mempool.h>

> @@ -4527,8 +4526,12 @@ rte_eth_add_first_rx_callback(uint16_t port_id, uint16_t queue_id,

>  	rte_spinlock_lock(&rte_eth_rx_cb_lock);

>  	/* Add the callbacks at first position */

>  	cb->next = rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];

> -	rte_smp_wmb();

> -	rte_eth_devices[port_id].post_rx_burst_cbs[queue_id] = cb;

> +	/* Stores to cb->fn, cb->param and cb->next should complete before

> +	 * cb is visible to data plane threads.

> +	 */

> +	__atomic_store_n(

> +		&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],

> +		cb, __ATOMIC_RELEASE);

>  	rte_spinlock_unlock(&rte_eth_rx_cb_lock);

> 

>  	return cb;

> --


Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>


> 2.17.1

Patch

diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 7858ad5f1..59a41c07f 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -26,7 +26,6 @@ 
 #include <rte_eal.h>
 #include <rte_per_lcore.h>
 #include <rte_lcore.h>
-#include <rte_atomic.h>
 #include <rte_branch_prediction.h>
 #include <rte_common.h>
 #include <rte_mempool.h>
@@ -4527,8 +4526,12 @@  rte_eth_add_first_rx_callback(uint16_t port_id, uint16_t queue_id,
 	rte_spinlock_lock(&rte_eth_rx_cb_lock);
 	/* Add the callbacks at first position */
 	cb->next = rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];
-	rte_smp_wmb();
-	rte_eth_devices[port_id].post_rx_burst_cbs[queue_id] = cb;
+	/* Stores to cb->fn, cb->param and cb->next should complete before
+	 * cb is visible to data plane threads.
+	 */
+	__atomic_store_n(
+		&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],
+		cb, __ATOMIC_RELEASE);
 	rte_spinlock_unlock(&rte_eth_rx_cb_lock);
 
 	return cb;