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| author |   John Garry <john.garry@huawei.com> | 2022-07-14 19:15:24 +0800 |
|---|---|---|
| committer |   Christoph Hellwig <hch@lst.de> | 2022-07-19 06:05:41 +0200 |
| commit | a229cc14f3395311b899e5e582b71efa8dd01df0 (patch) | |
| tree | c582777858d9da5c8d70cad910a04859b213fd8f /include/linux/dma-mapping.h | |
| parent | swiotlb: move struct io_tlb_slot to swiotlb.c (diff) | |
| download | linux-dev-a229cc14f3395311b899e5e582b71efa8dd01df0.tar.xz linux-dev-a229cc14f3395311b899e5e582b71efa8dd01df0.zip | |
dma-mapping: add dma_opt_mapping_size()
Streaming DMA mapping involving an IOMMU may be much slower for larger
total mapping size. This is because every IOMMU DMA mapping requires an
IOVA to be allocated and freed. IOVA sizes above a certain limit are not
cached, which can have a big impact on DMA mapping performance.
Provide an API for device drivers to know this "optimal" limit, such that
they may try to produce mapping which don't exceed it.
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'include/linux/dma-mapping.h')
| -rw-r--r-- | include/linux/dma-mapping.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index dca2b1355bb1..fe3849434b2a 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -144,6 +144,7 @@ int dma_set_mask(struct device *dev, u64 mask); int dma_set_coherent_mask(struct device *dev, u64 mask); u64 dma_get_required_mask(struct device *dev); size_t dma_max_mapping_size(struct device *dev); +size_t dma_opt_mapping_size(struct device *dev); bool dma_need_sync(struct device *dev, dma_addr_t dma_addr); unsigned long dma_get_merge_boundary(struct device *dev); struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size, @@ -266,6 +267,10 @@ static inline size_t dma_max_mapping_size(struct device *dev) { return 0; } +static inline size_t dma_opt_mapping_size(struct device *dev) +{ + return 0; +} static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr) { return false; |