Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits
From: Bart Van Assche
Date: Wed Jun 08 2022 - 13:33:42 EST
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.