[dpdk-dev] [PATCH] vhost: notify guest to fill buffer when there is no buffer
Linhaifeng
haifeng.lin at huawei.com
Thu Jan 29 14:50:55 CET 2015
On 2015/1/29 21:00, Xie, Huawei wrote:
>
>
>> -----Original Message-----
>> From: Linhaifeng [mailto:haifeng.lin at huawei.com]
>> Sent: Thursday, January 29, 2015 8:39 PM
>> To: Xie, Huawei; dev at dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH] vhost: notify guest to fill buffer when there is
>> no buffer
>>
>>
>>
>> On 2015/1/29 18:39, Xie, Huawei wrote:
>>
>>>> - if (count == 0)
>>>> + /* If there is no buffers we should notify guest to fill.
>>>> + * This is need when guest use virtio_net driver(not pmd).
>>>> + */
>>>> + if (count == 0) {
>>>> + if (!(vq->avail->flags &
>>>> VRING_AVAIL_F_NO_INTERRUPT))
>>>> + eventfd_write((int)vq->kickfd, 1);
>>>> return 0;
>>>> + }
>>>
>>> Haifeng:
>>> Is it the root cause and is it protocol required?
>>> Could you give a detailed description for that scenario?
>>>
>>
>> I use mz to send data from one VM1 to VM2.The two VM use virtio-net driver.
>> VM1 execute follow script:
>> for((i=0;i<999999999;i++));
>> do
>> mz eth0 -t udp -A 1.1.1.1 -B 1.1.1.2 -a 00:00:00:00:00:01 -b 00:00:00:00:00:02 -c
>> 10000000 -p 512
>> sleep 4
>> done
>>
>> VM2 execute follow command to watch:
>> watch -d ifconfig
>>
>> After many hours VM2 stop to receive data.
>>
>> Could you test it ?
>
>
> We could try next week after I send the whole patch.
> How many hours? Is it reproducible at your side? I inject packets through packet generator to guest for more than ten hours, haven't met issues.
About three hours.
What kind of driver you used in guest?virtio-net-pmd or virtio-net?
> As I said in another mail sent to you, could you dump the status of vring if you still have the spot?
How to dump the status of vring in guest?
> Could you please also reply to that mail?
>
Which mail?
> For the patch, if we have no root cause, I prefer not to apply it, so that we don't send more interrupts than needed to guest to affect performance.
I found that if we add this notify the performance is better(growth of 100kpps when use 64byte UDP packets)
> People could temporarily apply this patch as a work around.
>
> Or anyone
>
OK.I'm also not sure about this bug.I think i should do something to found the real reason.
>
>> --
>> Regards,
>> Haifeng
>
>
>
--
Regards,
Haifeng
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