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.leiz...@huawei.com/ Changes since v4: - tweak libata and other patch titles - Add Robin's tag (thanks!) - Clarify description of new DMA mapping API
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