From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH v1] add mtu set in virtio
Date: Mon, 29 Aug 2016 12:33:06 -0700
Message-ID: <20160829123306.4e2bf00d@xeon-e3>
References: <20160827005428.16556-1-sodey@sonusnet.com>
 <20160827171541.5f6b17c2@xeon-e3>
 <BN6PR03MB2740F9921796A56FB6E06EE0DAEE0@BN6PR03MB2740.namprd03.prod.outlook.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: "huawei.xie@intel.com" <huawei.xie@intel.com>,
 "yuanhan.liu@linux.intel.com" <yuanhan.liu@linux.intel.com>, "dev@dpdk.org"
 <dev@dpdk.org>
To: "Dey, Souvik" <sodey@sonusnet.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pf0-f171.google.com (mail-pf0-f171.google.com
 [209.85.192.171]) by dpdk.org (Postfix) with ESMTP id B328DFFA
 for <dev@dpdk.org>; Mon, 29 Aug 2016 21:32:55 +0200 (CEST)
Received: by mail-pf0-f171.google.com with SMTP id x72so55018849pfd.2
 for <dev@dpdk.org>; Mon, 29 Aug 2016 12:32:55 -0700 (PDT)
In-Reply-To: <BN6PR03MB2740F9921796A56FB6E06EE0DAEE0@BN6PR03MB2740.namprd03.prod.outlook.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 Sun, 28 Aug 2016 22:43:54 +0000
"Dey, Souvik" <sodey@sonusnet.com> wrote:

> Hi ,
> 	Currently as you have mentioned, I have changed the code to:
> static int 
>  virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu) 
>  {
>     struct virtio_hw *hw = dev->data->dev_private;
> -   if (unlikely(mtu < (uint32_t)hw->vtnet_hdr_size + ETHER_HDR_LEN)) {
> -       return -1;
> +   if (unlikely(mtu < VIRTIO_MIN_RX_BUFSIZE || mtu > VIRTIO_MAX_RX_PKTLEN)) {
> +	   PMD_INIT_LOG(ERR,"Mtu should be between 64 and 9728."
> +       return -EINVAL;
>     }
>     return 0;
>  }
> 
> Yes, we should support till 64K as the kernel does , but I need to go through the changes and test it properly before submitting it for review. Moreover I was thinking with the changes in the mtu, we should also support multi-segment buffers in kni. What do you suggest ?

This looks good, but you really don't need likely/unlikely in this code.
It is not at all performance critical.