On 30/06/2022 13:08, John Garry wrote:
Hi Christoph,
Can you please consider picking up this series? A few things to note
beforehand:
- I changed to only apply the mapping limit to SAS hosts in this
version. I would need a fresh ack from Martin for those SCSI parts, but
wanted to make sure you were ok with it.
- Damien had some doubt on updating the shost max_sectors as opposed to
the per-request queue default, but I think he's ok with it - see patch 4/5
Thanks,
John
As reported in [0], DMA mappings whose size exceeds the IOMMU IOVA caching
limit may see a big performance hit.
This series introduces a new DMA mapping API, dma_opt_mapping_size(), so
that drivers may know this limit when performance is a factor in the
mapping.
The SCSI SAS transport code is modified only to use this limit. For now I
did not want to touch other hosts as I have a concern that this change
could cause a performance regression.
I also added a patch for libata-scsi as it does not currently honour the
shost max_sectors limit.
[0]https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@xxxxxxxxxx/
Changes since v4:
- tweak libata and other patch titles
- Add Robin's tag (thanks!)
- Clarify description of new DMA mapping API
