From: John Garry <john.garry@huawei.com>
To: <damien.lemoal@opensource.wdc.com>, <joro@8bytes.org>,
<will@kernel.org>, <jejb@linux.ibm.com>,
<martin.petersen@oracle.com>, <hch@lst.de>,
<m.szyprowski@samsung.com>, <robin.murphy@arm.com>
Cc: <linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-ide@vger.kernel.org>, <iommu@lists.linux-foundation.org>,
<iommu@lists.linux.dev>, <linux-scsi@vger.kernel.org>,
<linuxarm@huawei.com>, John Garry <john.garry@huawei.com>
Subject: [PATCH v4 0/5] DMA mapping changes for SCSI core
Date: Mon, 27 Jun 2022 23:25:16 +0800 [thread overview]
Message-ID: <1656343521-62897-1-git-send-email-john.garry@huawei.com> (raw)
As reported in [0], DMA mappings whose size exceeds the IOMMU IOVA caching
limit may see a big performance hit.
This series introduces a new DMA mapping API, dma_opt_mapping_size(), so
that drivers may know this limit when performance is a factor in the
mapping.
The SCSI SAS transport code is modified only to use this limit. For now I
did not want to touch other hosts as I have a concern that this change
could cause a performance regression.
I also added a patch for libata-scsi as it does not currently honour the
shost max_sectors limit.
[0] https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/
[1] https://lore.kernel.org/linux-iommu/f5b78c9c-312e-70ab-ecbb-f14623a4b6e3@arm.com/
Changes since v3:
- Apply max DMA optimial limit to SAS hosts only
Note: Even though "scsi: core: Cap shost max_sectors only once when
adding" is a subset of a previous patch I did not transfer the RB tags
- Rebase on v5.19-rc4
Changes since v2:
- Rebase on v5.19-rc1
- Add Damien's tag to 2/4 (thanks)
Changes since v1:
- Relocate scsi_add_host_with_dma() dma_dev check (Reported by Dan)
- Add tags from Damien and Martin (thanks)
- note: I only added Martin's tag to the SCSI patch
John Garry (5):
dma-mapping: Add dma_opt_mapping_size()
dma-iommu: Add iommu_dma_opt_mapping_size()
scsi: core: Cap shost max_sectors according to DMA mapping limits only
once
scsi: scsi_transport_sas: Cap shost max_sectors according to DMA
optimal mapping limit
libata-scsi: Cap ata_device->max_sectors according to
shost->max_sectors
Documentation/core-api/dma-api.rst | 9 +++++++++
drivers/ata/libata-scsi.c | 1 +
drivers/iommu/dma-iommu.c | 6 ++++++
drivers/iommu/iova.c | 5 +++++
drivers/scsi/hosts.c | 5 +++++
drivers/scsi/scsi_lib.c | 4 ----
drivers/scsi/scsi_transport_sas.c | 6 ++++++
include/linux/dma-map-ops.h | 1 +
include/linux/dma-mapping.h | 5 +++++
include/linux/iova.h | 2 ++
kernel/dma/mapping.c | 12 ++++++++++++
11 files changed, 52 insertions(+), 4 deletions(-)
--
2.35.3
next reply other threads:[~2022-06-27 15:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-27 15:25 John Garry [this message]
2022-06-27 15:25 ` [PATCH v4 1/5] dma-mapping: Add dma_opt_mapping_size() John Garry
2022-06-28 11:23 ` Robin Murphy
2022-06-28 11:27 ` John Garry
2022-06-29 11:57 ` John Garry
2022-06-27 15:25 ` [PATCH v4 2/5] dma-iommu: Add iommu_dma_opt_mapping_size() John Garry
2022-06-28 10:56 ` Robin Murphy
2022-06-27 15:25 ` [PATCH v4 3/5] scsi: core: Cap shost max_sectors according to DMA mapping limits only once John Garry
2022-06-27 15:25 ` [PATCH v4 4/5] scsi: scsi_transport_sas: Cap shost max_sectors according to DMA optimal mapping limit John Garry
2022-06-27 15:25 ` [PATCH v4 5/5] libata-scsi: Cap ata_device->max_sectors according to shost->max_sectors John Garry
2022-06-27 23:24 ` Damien Le Moal
2022-06-28 7:54 ` John Garry
2022-06-28 9:14 ` Damien Le Moal
2022-06-28 11:33 ` John Garry
2022-06-29 5:40 ` Christoph Hellwig
2022-06-29 5:58 ` Damien Le Moal
2022-06-29 7:43 ` John Garry
2022-06-29 8:24 ` Damien Le Moal
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