netdev - Re: [PATCH v2 2/5] VSOCK: support fill data to mergeable rx buffer in host

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Date:   Thu, 13 Dec 2018 11:11:48 +0800
From:   jiangyiwen <jiangyiwen@...wei.com>
To:     David Miller <davem@...emloft.net>
CC:     <stefanha@...hat.com>, <mst@...hat.com>, <jasowang@...hat.com>,
        <netdev@...r.kernel.org>, <kvm@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH v2 2/5] VSOCK: support fill data to mergeable rx buffer in
 host

On 2018/12/13 3:09, David Miller wrote:
> From: jiangyiwen <jiangyiwen@...wei.com>
> Date: Wed, 12 Dec 2018 17:29:31 +0800
> 
>> diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
>> index 1d57ed3..2292f30 100644
>> --- a/include/uapi/linux/virtio_vsock.h
>> +++ b/include/uapi/linux/virtio_vsock.h
>> @@ -63,6 +63,11 @@ struct virtio_vsock_hdr {
>>  	__le32	fwd_cnt;
>>  } __attribute__((packed));
>>
>> +/* It add mergeable rx buffers feature */
>> +struct virtio_vsock_mrg_rxbuf_hdr {
>> +	__le16  num_buffers;    /* number of mergeable rx buffers */
>> +} __attribute__((packed));
>> +
> 
> I know the rest of this file uses 'packed' but this attribute should
> only be used if absolutely necessary as it incurs a
> non-trivial performance penalty for some architectures.
> 
> .
> 

Hi David,

I hope Host can fill fewer bytes into rx virtqueue, so
I keep structure virtio_vsock_mrg_rxbuf_hdr one byte
alignment.

Thanks,
Yiwen.