On Wed, Aug 25, 2021 at 6:35 PM John Garry [off-list ref] wrote:

On 25/08/2021 10:55, Will Deacon wrote:

quoted

On Tue, Aug 24, 2021 at 02:08:33PM -0400, Michael S. Tsirkin wrote:

quoted

On Wed, Aug 18, 2021 at 08:06:31PM +0800, Xie Yongji wrote:

quoted

Export alloc_iova_fast() and free_iova_fast() so that
some modules can make use of the per-CPU cache to get
rid of rbtree spinlock in alloc_iova() and free_iova()
during IOVA allocation.

Signed-off-by: Xie Yongji <redacted>

This needs ack from iommu maintainers. Guys?

Looks fine to me:

Acked-by: Will Deacon <will@kernel.org>

Will
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JFYI, There was a preliminary discussion to move the iova rcache code
(which the iova fast alloc and free functions are based on) out of the
iova code and maybe into dma-iommu (being the only user). There was
other motivation.

Would it be better to move the code into ./lib as a general library?

https://lore.kernel.org/linux-iommu/83de3911-145d-77c8-17c1-981e4ff825d3@arm.com/ (local)

Having more users complicates that...

Do we have some plan for this work? From our test [1],
iova_alloc_fast() is much better than iova_alloc(). So I'd like to use
it as much as possible

[1] https://lore.kernel.org/kvm/CACycT3steXFeg7NRbWpo2J59dpYcumzcvM2zcPJAVe40-EvvEg@mail.gmail.com/ (local)

Thanks,
Yongji