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To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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Cc: Rich Lane <rich.lane@bigswitch.com>, dev@dpdk.org,
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From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
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Date: Tue, 5 Apr 2016 13:34:18 +0800
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Subject: Re: [dpdk-dev] [PATCH v2] virtio: use zeroed memory for simple TX
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Hi,

On 4/5/2016 12:26 PM, Yuanhan Liu wrote:
> On Tue, Apr 05, 2016 at 11:20:05AM +0800, Tan, Jianfeng wrote:
>> Hi,
>>
>> On 4/5/2016 10:11 AM, Rich Lane wrote:
>>> For simple TX the virtio-net header must be zeroed, but it was using memory
>>> that had been initialized with indirect descriptor tables. This resulted in
>>> "unsupported gso type" errors from librte_vhost.
>>>
>>> We can use the same memory for every descriptor to save cachelines in the
>>> vswitch.
>> Pointing all virtio_net_hdr into the same memory may brings performance, but
>> how much? It also introduces difficulty to adding tso in future?
> simple rxtx will not be enabled when TSO is enabled.

Yes, I was missing simple rxtx is conflicting with 
ETH_TXQ_FLAGS_NOOFFLOADS, which indicates that simple rxtx does not want 
to fill any fields in the hdr.
Acked-by: Jianfeng Tan <jianfeng.tan@intel.com>

Thanks,
Jianfeng

>
> 	--yliu