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

Bart Van Assche
2022-06-08T17:33:38Z

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.