From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk
 API
Date: Thu, 17 Dec 2015 21:01:14 -0800
Message-ID: <20151217210114.534a7561@xeon-e3>
References: <1450049754-33635-1-git-send-email-huawei.xie@intel.com>
 <1450055682-51953-1-git-send-email-huawei.xie@intel.com>
 <1450055682-51953-2-git-send-email-huawei.xie@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: dev@dpdk.org
To: Huawei Xie <huawei.xie@intel.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pf0-f175.google.com (mail-pf0-f175.google.com
 [209.85.192.175]) by dpdk.org (Postfix) with ESMTP id CF9DA8D8D
 for <dev@dpdk.org>; Fri, 18 Dec 2015 06:01:08 +0100 (CET)
Received: by mail-pf0-f175.google.com with SMTP id v86so42662924pfa.2
 for <dev@dpdk.org>; Thu, 17 Dec 2015 21:01:08 -0800 (PST)
In-Reply-To: <1450055682-51953-2-git-send-email-huawei.xie@intel.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Mon, 14 Dec 2015 09:14:41 +0800
Huawei Xie <huawei.xie@intel.com> wrote:

> v2 changes:
>  unroll the loop a bit to help the performance
> 
> rte_pktmbuf_alloc_bulk allocates a bulk of packet mbufs.
> 
> There is related thread about this bulk API.
> http://dpdk.org/dev/patchwork/patch/4718/
> Thanks to Konstantin's loop unrolling.
> 
> Signed-off-by: Gerald Rogers <gerald.rogers@intel.com>
> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---
>  lib/librte_mbuf/rte_mbuf.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index f234ac9..4e209e0 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -1336,6 +1336,56 @@ static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp)
>  }
>  
>  /**
> + * Allocate a bulk of mbufs, initialize refcnt and reset the fields to default
> + * values.
> + *
> + *  @param pool
> + *    The mempool from which mbufs are allocated.
> + *  @param mbufs
> + *    Array of pointers to mbufs
> + *  @param count
> + *    Array size
> + *  @return
> + *   - 0: Success
> + */
> +static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool,
> +	 struct rte_mbuf **mbufs, unsigned count)
> +{
> +	unsigned idx = 0;
> +	int rc;
> +
> +	rc = rte_mempool_get_bulk(pool, (void **)mbufs, count);
> +	if (unlikely(rc))
> +		return rc;
> +
> +	switch (count % 4) {
> +	while (idx != count) {
> +		case 0:
> +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> +			rte_pktmbuf_reset(mbufs[idx]);
> +			idx++;
> +		case 3:
> +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> +			rte_pktmbuf_reset(mbufs[idx]);
> +			idx++;
> +		case 2:
> +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> +			rte_pktmbuf_reset(mbufs[idx]);
> +			idx++;
> +		case 1:
> +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> +			rte_pktmbuf_reset(mbufs[idx]);
> +			idx++;
> +	}
> +	}
> +	return 0;
> +}

This is weird. Why not just use Duff's device in a more normal manner.