Messages in this thread | | | Date | Wed, 6 Jul 2022 14:40:44 +0100 | Subject | Re: [PATCH v5 0/5] DMA mapping changes for SCSI core | From | John Garry <> |
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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@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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