| Message ID | 1657797329-98541-6-git-send-email-john.garry@huawei.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | DMA mapping changes for SCSI core | expand |
On 7/14/22 20:15, John Garry wrote: > 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(+) > > diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c > index 12bff64dade6..2f88c61216ee 100644 > --- a/drivers/scsi/scsi_transport_sas.c > +++ b/drivers/scsi/scsi_transport_sas.c > @@ -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->dma_mask) { > + shost->opt_sectors = min_t(unsigned int, shost->max_sectors, > + dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT); > + } > + > return 0; > } > Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c index 12bff64dade6..2f88c61216ee 100644 --- a/drivers/scsi/scsi_transport_sas.c +++ b/drivers/scsi/scsi_transport_sas.c @@ -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->dma_mask) { + shost->opt_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(+)