[dpdk-dev] [PATCH v2 12/12] net/vhost: support to run in the secondary process

Tan, Jianfeng jianfeng.tan at intel.com
Mon Oct 2 01:48:04 CEST 2017

On 9/30/2017 7:49 PM, Yuanhan Liu wrote:
> On Sat, Sep 30, 2017 at 12:06:44PM 0000, Jianfeng Tan wrote:
>>>>>> +	/* share callfd and kickfd */
>>>>>> +	params->type = VHOST_MSG_TYPE_SET_FDS;
>>>>>> +	vring_num = rte_vhost_get_vring_num(vid);
>>>>>> +	for (i = 0; i < vring_num; i++) {
>>>>>> +		if (rte_vhost_get_vhost_vring(vid, i, &vring) < 0) {
>>>>> If you save the fds here, you don't have to get it every time when there
>>>>> is a new secondary process attached. Then as I have suggested firstly,
>>>>> you don't have to introduce callfd_pri in the vhost lib.
>>>> If we don't introduce callfd_pri, when we do virtqueue cleanup (or similar
>>>> operations) in vhost lib, it will wrongly close fds belonging to secondary
>>>> process.
>>>> You remind me that, instead of introduce callfd_pri, we can introduce
>>>> callfd_effective, to reduce the modification lines.
>>> It's not about how many lines are modified. You were adding "effective"
>>> fds, which is a semantic change. It makes the logic a bit more complex.
>>> What's worse, it even doesn't resolve the issue completely.
>> Yes, it still has limitation. Just wonder if possible to move event fd
>> write out of vhost lib.
> It could be another solution: we have the valid fd and vring_avail
> outside the vhost lib. It's just that the callfd write is inside
> the vhost lib. If you just take it out (remove it), it breaks some
> users who rely on it: it's an API behaviour change.

Make sense.


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