diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2023-10-05 16:40:30 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2023-10-13 16:10:39 +0100 |
| commit | 65033574ade97afccba074d837fd269903a83a9a (patch) | |
| tree | b6124c5c373f37bb368bd18f0089fb44c048c8de /arch/arm64/mm | |
| parent | 6465e260f48790807eef06b583b38ca9789b6072 (diff) | |
arm64: swiotlb: Reduce the default size if no ZONE_DMA bouncing needed
With CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC enabled, the arm64 kernel still
allocates the default SWIOTLB buffer (64MB) even if ZONE_DMA is disabled
or all the RAM fits into this zone. However, this potentially wastes a
non-negligible amount of memory on platforms with little RAM.
Reduce the SWIOTLB size to 1MB per 1GB of RAM if only needed for
kmalloc() buffer bouncing.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Ross Burton <ross.burton@arm.com>
Cc: Ross Burton <ross.burton@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Diffstat (limited to 'arch/arm64/mm')
| -rw-r--r-- | arch/arm64/mm/init.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 8a0f8604348b..8deec68028ac 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -16,6 +16,7 @@ #include <linux/nodemask.h> #include <linux/initrd.h> #include <linux/gfp.h> +#include <linux/math.h> #include <linux/memblock.h> #include <linux/sort.h> #include <linux/of.h> @@ -493,8 +494,16 @@ void __init mem_init(void) { bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); - if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC)) + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { + /* + * If no bouncing needed for ZONE_DMA, reduce the swiotlb + * buffer for kmalloc() bouncing to 1MB per 1GB of RAM. + */ + unsigned long size = + DIV_ROUND_UP(memblock_phys_mem_size(), 1024); + swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); swiotlb = true; + } swiotlb_init(swiotlb, SWIOTLB_VERBOSE); |