Re: [dpdk-dev] [PATCH] kni: optimizing the rte_kni_rx_burst

[Thomas Monjalon <thomas.monjalon@6wind.com>]

Is there anyone interested in KNI to review this patch please?


2014-07-23 12:15, Hemant Agrawal:
> The current implementation of rte_kni_rx_burst polls the fifo for buffers.
> Irrespective of success or failure, it allocates the mbuf and try to put them into the alloc_q
> if the buffers are not added to alloc_q, it frees them.
> This waste lots of cpu cycles in allocating and freeing the buffers if alloc_q is full.
> 
> The logic has been changed to:
> 1. Initially allocand add buffer(burstsize) to alloc_q
> 2. Add buffers to alloc_q only when you are pulling out the buffers.
> 
> Signed-off-by: Hemant Agrawal <Hemant@freescale.com>
> ---
>  lib/librte_kni/rte_kni.c |    8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
> index 76feef4..01e85f8 100644
> --- a/lib/librte_kni/rte_kni.c
> +++ b/lib/librte_kni/rte_kni.c
> @@ -263,6 +263,9 @@ rte_kni_alloc(struct rte_mempool *pktmbuf_pool,
>  
>  	ctx->in_use = 1;
>  
> +	/* Allocate mbufs and then put them into alloc_q */
> +	kni_allocate_mbufs(ctx);
> +
>  	return ctx;
>  
>  fail:
> @@ -369,8 +372,9 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf **mbufs, unsigned num)
>  {
>  	unsigned ret = kni_fifo_get(kni->tx_q, (void **)mbufs, num);
>  
> -	/* Allocate mbufs and then put them into alloc_q */
> -	kni_allocate_mbufs(kni);
> +	/* If buffers removed, allocate mbufs and then put them into alloc_q */
> +	if(ret)
> +		kni_allocate_mbufs(kni);
>  
>  	return ret;
>  }