Re: [PATCH v2] iommu/iova: Optimize alloc_iova with rbtree_augmented

[Peng Zhang]

> Though only 3-4 drivers use alloc_iova() directly, in my understanding
>
> your test has simulated the worst case, rcache doesn't work at all,
>
> "alloc_iova" +“remove_iova” number looks great for worst case.

There is another case, when the size to allocate greater to 2^5, even if 
alloc_iova_fast() is used, alloc_iova() will always be called because 
the maximum iova size that rcache supports to allocate is 32.
IOVA_RANGE_CACHE_MAX_SIZE specifies the maximum size.

Thanks,

Peng