57 lines
1.8 KiB
Diff
57 lines
1.8 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Catalin Marinas <[email protected]>
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Date: Wed, 10 Apr 2024 08:25:37 -0400
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Subject: arm64: swiotlb: Reduce the default size if no ZONE_DMA bouncing
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needed
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With CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC enabled, the arm64 kernel still
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allocates the default SWIOTLB buffer (64MB) even if ZONE_DMA is disabled
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or all the RAM fits into this zone. However, this potentially wastes a
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non-negligible amount of memory on platforms with little RAM.
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Reduce the SWIOTLB size to 1MB per 1GB of RAM if only needed for
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kmalloc() buffer bouncing.
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Signed-off-by: Catalin Marinas <[email protected]>
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Suggested-by: Ross Burton <[email protected]>
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Cc: Ross Burton <[email protected]>
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Cc: Will Deacon <[email protected]>
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Reviewed-by: Robin Murphy <[email protected]>
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---
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arch/arm64/mm/init.c | 11 +++++++++-
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1 file changed, 10 insertions(+), 1 deletion(-)
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diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
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index 111111111111..222222222222 100644
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--- a/arch/arm64/mm/init.c
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+++ b/arch/arm64/mm/init.c
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@@ -16,6 +16,7 @@
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#include <linux/nodemask.h>
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#include <linux/initrd.h>
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#include <linux/gfp.h>
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+#include <linux/math.h>
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#include <linux/memblock.h>
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#include <linux/sort.h>
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#include <linux/of.h>
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@@ -493,8 +494,16 @@ void __init mem_init(void)
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{
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bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit);
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- if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC))
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+ if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) {
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+ /*
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+ * If no bouncing needed for ZONE_DMA, reduce the swiotlb
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+ * buffer for kmalloc() bouncing to 1MB per 1GB of RAM.
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+ */
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+ unsigned long size =
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+ DIV_ROUND_UP(memblock_phys_mem_size(), 1024);
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+ swiotlb_adjust_size(min(swiotlb_size_or_default(), size));
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swiotlb = true;
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+ }
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swiotlb_init(swiotlb, SWIOTLB_VERBOSE);
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--
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Armbian
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