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| /openbmc/linux/drivers/scsi/ |
| H A D | scsi_transport_sas.c | 4cbfca5f Thu Jul 14 06:15:28 CDT 2022 John Garry <john.garry@huawei.com> scsi: scsi_transport_sas: cap shost opt_sectors according to DMA optimal limit
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>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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