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From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
To: Kiran Kumar <kkokkilagadda@caviumnetworks.com>
Cc: maciej.czekaj@caviumnetworks.com, ferruh.yigit@intel.com,
	dev@dpdk.org, stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] net/thunderx: avoid sq door bell writes on zero packets
Date: Wed, 11 Jul 2018 14:35:59 +0530	[thread overview]
Message-ID: <20180711090557.GA22077@jerin> (raw)
In-Reply-To: <1531297476-4604-1-git-send-email-kkokkilagadda@caviumnetworks.com>

-----Original Message-----
> Date: Wed, 11 Jul 2018 13:54:36 +0530
> From: Kiran Kumar <kkokkilagadda@caviumnetworks.com>
> To: jerin.jacob@caviumnetworks.com, maciej.czekaj@caviumnetworks.com,
>  ferruh.yigit@intel.com
> Cc: dev@dpdk.org, Kiran Kumar <kkokkilagadda@caviumnetworks.com>,
>  stable@dpdk.org
> Subject: [dpdk-dev] [PATCH v2] net/thunderx: avoid sq door bell writes on
>  zero packets
> X-Mailer: git-send-email 2.7.4
> 
> Avoid sq door bell write on zero packet case to reduce additional
> traffic on register bus.
> 
> Fixes: 1c421f18e0 ("net/thunderx: add single and multi-segment Tx")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Kiran Kumar <kkokkilagadda@caviumnetworks.com>

Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

> ---
>  v2 Changes:
>  - changed summery and description.
>  - added same optimization to nicvf_xmit_pkts_multiseg
> 
>  drivers/net/thunderx/nicvf_rxtx.c | 24 ++++++++++++++----------
>  1 file changed, 14 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/thunderx/nicvf_rxtx.c b/drivers/net/thunderx/nicvf_rxtx.c
> index 72305d9..6e075e2 100644
> --- a/drivers/net/thunderx/nicvf_rxtx.c
> +++ b/drivers/net/thunderx/nicvf_rxtx.c
> @@ -162,12 +162,14 @@ nicvf_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  		free_desc -= TX_DESC_PER_PKT;
>  	}
> 
> -	sq->tail = tail;
> -	sq->xmit_bufs += i;
> -	rte_wmb();
> +	if (likely(i)) {
> +		sq->tail = tail;
> +		sq->xmit_bufs += i;
> +		rte_wmb();
> 
> -	/* Inform HW to xmit the packets */
> -	nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
> +		/* Inform HW to xmit the packets */
> +		nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
> +	}
>  	return i;
>  }
> 
> @@ -218,12 +220,14 @@ nicvf_xmit_pkts_multiseg(void *tx_queue, struct rte_mbuf **tx_pkts,
>  		}
>  	}
> 
> -	sq->tail = tail;
> -	sq->xmit_bufs += used_bufs;
> -	rte_wmb();
> +	if (likely(used_desc)) {
> +		sq->tail = tail;
> +		sq->xmit_bufs += used_bufs;
> +		rte_wmb();
> 
> -	/* Inform HW to xmit the packets */
> -	nicvf_addr_write(sq->sq_door, used_desc);
> +		/* Inform HW to xmit the packets */
> +		nicvf_addr_write(sq->sq_door, used_desc);
> +	}
>  	return i;
>  }
> 
> --
> 2.7.4
> 

  reply	other threads:[~2018-07-11  9:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-11  7:22 [dpdk-dev] [PATCH] net/thunderx: Block sq door writes on zero pkts Kiran Kumar
2018-07-11  7:37 ` Jerin Jacob
2018-07-11  8:24 ` [dpdk-dev] [PATCH v2] net/thunderx: avoid sq door bell writes on zero packets Kiran Kumar
2018-07-11  9:05   ` Jerin Jacob [this message]
2018-07-18  9:41     ` Ferruh Yigit

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