linux-kernel - Re: [RFC PATCH net-next 02/12] vhost_net: introduce vhost_exceeds

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Date:   Tue, 22 May 2018 20:27:51 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:     mst@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [RFC PATCH net-next 02/12] vhost_net: introduce
 vhost_exceeds_weight()



On 2018年05月22日 00:29, Jesse Brandeburg wrote:
> On Mon, 21 May 2018 17:04:23 +0800 Jason wrote:
>> Signed-off-by: Jason Wang <jasowang@...hat.com>
>> ---
>>   drivers/vhost/net.c | 13 ++++++++-----
>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>> index 15d191a..de544ee 100644
>> --- a/drivers/vhost/net.c
>> +++ b/drivers/vhost/net.c
>> @@ -479,6 +479,12 @@ static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
>>   	return len;
>>   }
>>   
>> +static bool vhost_exceeds_weight(int pkts, int total_len)
>> +{
>> +	return unlikely(total_len >= VHOST_NET_WEIGHT) ||
>> +	       unlikely(pkts >= VHOST_NET_PKT_WEIGHT);
> I was going to say just one unlikely, but then the caller of this
> function also says unlikely(vhost_exceeds...), so I think you should
> just drop the unlikely statements here (both of them)

Ok.

>
>> +}
>> +
>>   /* Expects to be always run from workqueue - which acts as
>>    * read-size critical section for our kind of RCU. */
>>   static void handle_tx(struct vhost_net *net)
>> @@ -570,7 +576,6 @@ static void handle_tx(struct vhost_net *net)
>>   			msg.msg_control = NULL;
>>   			ubufs = NULL;
>>   		}
>> -
> unrelated whitespace changes?

Yes.

Thanks

>
>>   		total_len += len;
>>   		if (total_len < VHOST_NET_WEIGHT &&
>>   		    !vhost_vq_avail_empty(&net->dev, vq) &&
>> @@ -600,8 +605,7 @@ static void handle_tx(struct vhost_net *net)
>>   		else
>>   			vhost_zerocopy_signal_used(net, vq);
>>   		vhost_net_tx_packet(net);
>> -		if (unlikely(total_len >= VHOST_NET_WEIGHT) ||
>> -		    unlikely(++sent_pkts >= VHOST_NET_PKT_WEIGHT)) {
>> +		if (unlikely(vhost_exceeds_weight(++sent_pkts, total_len))) {
>>   			vhost_poll_queue(&vq->poll);
>>   			break;
>>   		}
>> @@ -887,8 +891,7 @@ static void handle_rx(struct vhost_net *net)
>>   		if (unlikely(vq_log))
>>   			vhost_log_write(vq, vq_log, log, vhost_len);
>>   		total_len += vhost_len;
>> -		if (unlikely(total_len >= VHOST_NET_WEIGHT) ||
>> -		    unlikely(++recv_pkts >= VHOST_NET_PKT_WEIGHT)) {
>> +		if (unlikely(vhost_exceeds_weight(++recv_pkts, total_len))) {
>>   			vhost_poll_queue(&vq->poll);
>>   			goto out;
>>   		}