On 5/13/21 12:01 AM, Tianyu Lan wrote:

Hi Christoph and Konrad:
      Current Swiotlb bounce buffer uses a pool for all devices. There
is a high overhead to get or free bounce buffer during performance test.
Swiotlb code now use a global spin lock to protect bounce buffer data.
Several device queues try to acquire the spin lock and this introduce
additional overhead.

For performance and security perspective, each devices should have a
separate swiotlb bounce buffer pool and so this part needs to rework.
I want to check this is right way to resolve performance issues with 
swiotlb bounce buffer. If you have some other suggestions,welcome.

Is this what you want?

https://lore.kernel.org/linux-iommu/20210510095026.3477496-1-tientzu@chromium.org/ (local)

Best regards,
baolu