Re: [RFC PATCH v3 4/8] vfio/type1: Pre-map more pages than requested in the IOPF handling

[Shenming Lu]

On 2021/5/19 2:58, Alex Williamson wrote:
> On Fri, 9 Apr 2021 11:44:16 +0800
> Shenming Lu <lushenming@xxxxxxxxxx> wrote:
> 
>> To optimize for fewer page fault handlings, we can pre-map more pages
>> than requested at once.
>>
>> Note that IOPF_PREMAP_LEN is just an arbitrary value for now, which we
>> could try further tuning.
> 
> I'd prefer that the series introduced full end-to-end functionality
> before trying to improve performance.  The pre-map value seems
> arbitrary here and as noted in the previous patch, the IOMMU API does
> not guarantee unmaps of ranges smaller than the original mapping.  This
> would need to map with single page granularity in order to guarantee
> page granularity at the mmu notifier when the IOMMU supports
> superpages.  Thanks,

Yeah, I will drop this patch in the current stage.

Thanks,
Shenming

> 
> Alex
> 
> .
>