Re: [PATCH 0/5] optimize the downtime for vfio migration

[Longpeng (Mike, Cloud Infrastructure Service Product Dept.)]

在 2021/8/25 18:05, Philippe Mathieu-Daudé 写道:
> Cc'ing David/Juan for migration big picture (just in case).
> 
> On 8/25/21 9:56 AM, Longpeng(Mike) wrote:
>> In vfio migration resume phase, the cost would increase if the
>> vfio device has more unmasked vectors. We try to optimize it in
>> this series.
>>
>> Patch 1 & 2 are simple code cleanups.
>> Patch 3 defers to set irqs to vfio core.
>> Patch 4 & 5 defer to commit the route to KVM core. 
>>
>> The test VM has 128 vcpus and 8 VF (with 65 vectors enabled),
>> we mesure the cost of the vfio_msix_enable for each one, and
>> we can see the total cost can be significantly reduced.
>>
>>         Origin         Apply Patch 3     Apply Patch 3/4/5   
>> 1st     8              4                 2
>> 2nd     15             11                2
>> 3rd     22             18                2
>> 4th     24             25                3
>> 5th     36             33                2
>> 6th     44             40                3
>> 7th     51             47                3
>> 8th     58             54                4
>> Total   258ms          232ms             21ms
>>
>>
>> Longpeng (Mike) (5):
>>   vfio: use helper to simplfy the failure path in vfio_msi_enable
>>   msix: simplfy the conditional in msix_set/unset_vector_notifiers
>>   vfio: defer to enable msix in migration resume phase
>>   kvm: irqchip: support defer to commit the route
>>   vfio: defer to commit kvm route in migraiton resume phase
> 
> Overall makes sense and LGTM but migration/KVM are not my area :/
>
Thanks all the same :)

> .
>