Re: [dpdk-stable] [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Chenbo,

On 6/25/21 1:37 PM, Xia, Chenbo wrote:
> Hi Maxime,
> 
>> -----Original Message-----
>> From: stable <stable-bounces@dpdk.org> On Behalf Of Xia, Chenbo
>> Sent: Friday, June 25, 2021 10:56 AM
>> To: Maxime Coquelin <maxime.coquelin@redhat.com>; dev@dpdk.org;
>> david.marchand@redhat.com
>> Cc: stable@dpdk.org
>> Subject: Re: [dpdk-stable] [PATCH v6 4/7] vhost: fix NUMA reallocation
>> with multiqueue
>>
>> Hi Maxime,
>>
>>> -----Original Message-----
>>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> Sent: Friday, June 18, 2021 10:04 PM
>>> To: dev@dpdk.org; david.marchand@redhat.com; Xia, Chenbo
>> <chenbo.xia@intel.com>
>>> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>; stable@dpdk.org
>>> Subject: [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue
>>>
>>> Since the Vhost-user device initialization has been reworked,
>>> enabling the application to start using the device as soon as
>>> the first queue pair is ready, NUMA reallocation no more
>>> happened on queue pairs other than the first one since
>>> numa_realloc() was returning early if the device was running.
>>>
>>> This patch fixes this issue by only preventing the device
>>> metadata to be allocated if the device is running. For the
>>> virtqueues, a vring state change notification is sent to
>>> notify the application of its disablement. Since the callback
>>> is supposed to be blocking, it is safe to reallocate it
>>> afterwards.
>>>
>>> Fixes: d0fcc38f5fa4 ("vhost: improve device readiness notifications")
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> ---
>>>  lib/vhost/vhost_user.c | 13 ++++++++++---
>>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
>>> index 82adf80fe5..51b96a0716 100644
>>> --- a/lib/vhost/vhost_user.c
>>> +++ b/lib/vhost/vhost_user.c
>>> @@ -488,12 +488,16 @@ numa_realloc(struct virtio_net *dev, int index)
>>>  	struct batch_copy_elem *new_batch_copy_elems;
>>>  	int ret;
>>>
>>> -	if (dev->flags & VIRTIO_DEV_RUNNING)
>>> -		return dev;
>>> -
>>>  	old_dev = dev;
>>>  	vq = old_vq = dev->virtqueue[index];
>>>
>>> +	/*
>>> +	 * If VQ is ready, it is too late to reallocate, it certainly
>> already
>>> +	 * happened anyway on VHOST_USER_SET_VRING_ADRR.
>>> +	 */
>>> +	if (vq->ready)
>>> +		return dev;
>>> +
>>>  	ret = get_mempolicy(&newnode, NULL, 0, old_vq->desc,
>>>  			    MPOL_F_NODE | MPOL_F_ADDR);
>>>
>>> @@ -558,6 +562,9 @@ numa_realloc(struct virtio_net *dev, int index)
>>>  		rte_free(old_vq);
>>>  	}
>>>
>>> +	if (dev->flags & VIRTIO_DEV_RUNNING)
>>> +		goto out;
>>> +
>>
>> Since we don't realloc when vq is ready, there is no case that vq not
>> ready but
>> device still running, right?
> 
> Sorry, I forgot DEV_RUNNING now only requires 1 qpair ready now ☹
> Ignore above comments..

No problem, thanks for the review!

> Thanks,
> Chenbo
> 
>>
>> Thanks,
>> Chenbo
>>
>>>  	/* check if we need to reallocate dev */
>>>  	ret = get_mempolicy(&oldnode, NULL, 0, old_dev,
>>>  			    MPOL_F_NODE | MPOL_F_ADDR);
>>> --
>>> 2.31.1
>