[dpdk-dev] [PATCH v1 2/2] ring: use wfe to wait for ring tail update on aarch64

[Honnappa Nagarahalli]

<snip>

Hi Gavin,
	There are other sync modes added to rte_ring library. Can you please extend this to other rte_pause() calls in the library?

Thanks,
Honnappa

> Subject: [PATCH v1 2/2] ring: use wfe to wait for ring tail update on aarch64
> 
> Instead of polling for tail to be updated, use wfe instruction.
> 
> Signed-off-by: Gavin Hu <gavin.hu at arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> Reviewed-by: Steve Capper <steve.capper at arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl at arm.com>
> Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> ---
>  lib/librte_ring/rte_ring_c11_mem.h | 4 ++--
> lib/librte_ring/rte_ring_generic.h | 3 +--
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_ring/rte_ring_c11_mem.h
> b/lib/librte_ring/rte_ring_c11_mem.h
> index 0fb73a337..764d8f186 100644
> --- a/lib/librte_ring/rte_ring_c11_mem.h
> +++ b/lib/librte_ring/rte_ring_c11_mem.h
> @@ -2,6 +2,7 @@
>   *
>   * Copyright (c) 2017,2018 HXT-semitech Corporation.
>   * Copyright (c) 2007-2009 Kip Macy kmacy at freebsd.org
> + * Copyright (c) 2019 Arm Limited
>   * All rights reserved.
>   * Derived from FreeBSD's bufring.h
>   * Used as BSD-3 Licensed with permission from Kip Macy.
> @@ -21,8 +22,7 @@ update_tail(struct rte_ring_headtail *ht, uint32_t
> old_val, uint32_t new_val,
>  	 * we need to wait for them to complete
>  	 */
>  	if (!single)
> -		while (unlikely(ht->tail != old_val))
> -			rte_pause();
> +		rte_wait_until_equal_relaxed_32(&ht->tail, old_val);
> 
>  	__atomic_store_n(&ht->tail, new_val, __ATOMIC_RELEASE);  } diff --
> git a/lib/librte_ring/rte_ring_generic.h b/lib/librte_ring/rte_ring_generic.h
> index 953cdbbd5..682852783 100644
> --- a/lib/librte_ring/rte_ring_generic.h
> +++ b/lib/librte_ring/rte_ring_generic.h
> @@ -23,8 +23,7 @@ update_tail(struct rte_ring_headtail *ht, uint32_t
> old_val, uint32_t new_val,
>  	 * we need to wait for them to complete
>  	 */
>  	if (!single)
> -		while (unlikely(ht->tail != old_val))
> -			rte_pause();
> +		rte_wait_until_equal_relaxed_32(&ht->tail, old_val);
> 
>  	ht->tail = new_val;
>  }
> --
> 2.17.1