net/iavf: replace SMP barrier with thread fence
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Commit Message
Replace the SMP barrier with atomic thread fence for iavf hw ring scan
in the bulk Rx path.
This patch introduces a change to the iavf driver that was already added
to the i40e driver [1] as part of the adoption of the use of compiler
atomics.
[1] https://patches.dpdk.org/project/dpdk/patch/20210706065404.25137-3-
joyce.kong@arm.com/
Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Reviewed-by: Joyce Kong <joyce.kong@arm.com>
---
drivers/net/iavf/iavf_rxtx.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Comments
> -----Original Message-----
> From: Kathleen Capella <kathleen.capella@arm.com>
> Sent: Tuesday, March 8, 2022 3:27 AM
> To: Wu, Jingjing <jingjing.wu@intel.com>; Xing, Beilei <beilei.xing@intel.com>
> Cc: dev@dpdk.org; nd@arm.com; honnappa.nagarahalli@arm.com;
> joyce.kong@arm.com; Kathleen Capella <kathleen.capella@arm.com>
> Subject: [PATCH] net/iavf: replace SMP barrier with thread fence
>
> Replace the SMP barrier with atomic thread fence for iavf hw ring scan in the
> bulk Rx path.
>
> This patch introduces a change to the iavf driver that was already added to the
> i40e driver [1] as part of the adoption of the use of compiler atomics.
>
> [1] https://patches.dpdk.org/project/dpdk/patch/20210706065404.25137-3-
> joyce.kong@arm.com/
Better replace URL with below commit line
Commit 8649e2356689 ("net/i40e: replace SMP barrier with thread fence in Rx")
Btw, the patch will be deferred to the next release as it's not a critical fix.
> -----Original Message-----
> From: Kathleen Capella <kathleen.capella@arm.com>
> Sent: Tuesday, March 8, 2022 3:27 AM
> To: Wu, Jingjing <jingjing.wu@intel.com>; Xing, Beilei <beilei.xing@intel.com>
> Cc: dev@dpdk.org; nd@arm.com; honnappa.nagarahalli@arm.com;
> joyce.kong@arm.com; Kathleen Capella <kathleen.capella@arm.com>
> Subject: [PATCH] net/iavf: replace SMP barrier with thread fence
>
> Replace the SMP barrier with atomic thread fence for iavf hw ring scan in the
> bulk Rx path.
>
> This patch introduces a change to the iavf driver that was already added to
> the i40e driver [1] as part of the adoption of the use of compiler atomics.
>
> [1] https://patches.dpdk.org/project/dpdk/patch/20210706065404.25137-3-
> joyce.kong@arm.com/
Replaced with
[1] Commit 8649e2356689 ("net/i40e: replace SMP barrier with thread fence in Rx")
>
> Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
> Reviewed-by: Joyce Kong <joyce.kong@arm.com>
Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>
Applied to dpdk-next-net-intel.
Thanks
Qi
@@ -1843,7 +1843,8 @@ iavf_rx_scan_hw_ring_flex_rxd(struct iavf_rx_queue *rxq)
for (j = IAVF_LOOK_AHEAD - 1; j >= 0; j--)
s[j] = rte_le_to_cpu_16(rxdp[j].wb.status_error0);
- rte_smp_rmb();
+ /* This barrier is to order loads of different words in the descriptor */
+ rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
/* Compute how many contiguous DD bits were set */
for (j = 0, nb_dd = 0; j < IAVF_LOOK_AHEAD; j++) {
@@ -1946,7 +1947,8 @@ iavf_rx_scan_hw_ring(struct iavf_rx_queue *rxq)
IAVF_RXD_QW1_STATUS_SHIFT;
}
- rte_smp_rmb();
+ /* This barrier is to order loads of different words in the descriptor */
+ rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
/* Compute how many contiguous DD bits were set */
for (j = 0, nb_dd = 0; j < IAVF_LOOK_AHEAD; j++) {