@@ -225,6 +225,7 @@ static int sas_host_setup(struct transport_container *tc, struct device *dev,
{
struct Scsi_Host *shost = dev_to_shost(dev);
struct sas_host_attrs *sas_host = to_sas_host_attrs(shost);
+ struct device *dma_dev = shost->dma_dev;
INIT_LIST_HEAD(&sas_host->rphy_list);
mutex_init(&sas_host->lock);
@@ -236,6 +237,11 @@ static int sas_host_setup(struct transport_container *tc, struct device *dev,
dev_printk(KERN_ERR, dev, "fail to a bsg device %d\n",
shost->host_no);
+ if (dma_dev) {
+ shost->max_sectors = min_t(unsigned int, shost->max_sectors,
+ dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT);
+ }
+
return 0;
}
Streaming DMA mappings may be considerably slower when mappings go through an IOMMU and the total mapping length is somewhat long. This is because the IOMMU IOVA code allocates and free an IOVA for each mapping, which may affect performance. For performance reasons set the request queue max_sectors from dma_opt_mapping_size(), which knows this mapping limit. Signed-off-by: John Garry <john.garry@huawei.com> --- drivers/scsi/scsi_transport_sas.c | 6 ++++++ 1 file changed, 6 insertions(+)