[External] Re: [PATCH] Revert "nvme-pci: clamp max_hw_sectors based on DMA optimized limitation"

[Keith Busch]

On Fri, Oct 09, 2026 at 09:11:56AM +0000, Adrian Huang12 wrote:
> 
> BTW, with this reverted patch, I'm setting up the test environment to
> check whether the issue does not appear with a newer kernel that
> includes the updated IOMMU subsystem. I'll share the results by the
> end of next week.

It does sound like an IOMMU implementation issue if the revert regresses
your testing. Let's say the application wants to write 1MB of data:
we're DMA mapping the same total amount either way, so I don't think it
should have been more efficient for the driver to send eight 128k
mapping requests vs a single 1MB.