Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits

[Bart Van Assche]

On 6/6/22 02:30, John Garry wrote:
+       if (dma_dev->dma_mask) {
+               shost->max_sectors = min_t(unsigned int, shost->max_sectors,
+                               dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT);
+       }

Since IOVA_RANGE_CACHE_MAX_SIZE = 6 this limits max_sectors to 2**6 * 
PAGE_SIZE or 256 KiB if the page size is 4 KiB. I think that's too 
small. Some (SRP) storage arrays require much larger transfers to 
achieve optimal performance.

Thanks,

Bart.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu