From 5d2efba64b231a1733c4048d1708d77e07f26426 Mon Sep 17 00:00:00 2001 From: Linas Vepstas Date: Mon, 30 Oct 2006 16:15:59 +1100 Subject: [POWERPC] Use 4kB iommu pages even on 64kB-page systems The 10Gigabit ethernet device drivers appear to be able to chew up all 256MB of TCE mappings on pSeries systems, as evidenced by numerous error messages: iommu_alloc failed, tbl c0000000010d5c48 vaddr c0000000d875eff0 npages 1 Some experimentation indicates that this is essentially because one 1500 byte ethernet MTU gets mapped as a 64K DMA region when the large 64K pages are enabled. Thus, it doesn't take much to exhaust all of the available DMA mappings for a high-speed card. This patch changes the iommu allocator to work with its own unique, distinct page size. Although the patch is long, its actually quite simple: it just #defines a distinct IOMMU_PAGE_SIZE and then uses this in all the places that matter. As a side effect, it also dramatically improves network performance on platforms with H-calls on iommu translation inserts/removes (since we no longer call it 16 times for a 1500 bytes packet when the iommu HW is still 4k). In the future, we might want to make the IOMMU_PAGE_SIZE a variable in the iommu_table instance, thus allowing support for different HW page sizes in the iommu itself. Signed-off-by: Linas Vepstas Signed-off-by: Benjamin Herrenschmidt Acked-by: Olof Johansson Acked-by: Stephen Rothwell Signed-off-by: Paul Mackerras --- include/asm-powerpc/iommu.h | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'include/asm-powerpc/iommu.h') diff --git a/include/asm-powerpc/iommu.h b/include/asm-powerpc/iommu.h index a5e98641a2a..39fad685ffa 100644 --- a/include/asm-powerpc/iommu.h +++ b/include/asm-powerpc/iommu.h @@ -22,17 +22,35 @@ #define _ASM_IOMMU_H #ifdef __KERNEL__ -#include +#include #include #include #include +#include +#include + +#define IOMMU_PAGE_SHIFT 12 +#define IOMMU_PAGE_SIZE (ASM_CONST(1) << IOMMU_PAGE_SHIFT) +#define IOMMU_PAGE_MASK (~((1 << IOMMU_PAGE_SHIFT) - 1)) +#define IOMMU_PAGE_ALIGN(addr) _ALIGN_UP(addr, IOMMU_PAGE_SIZE) + +#ifndef __ASSEMBLY__ + +/* Pure 2^n version of get_order */ +static __inline__ __attribute_const__ int get_iommu_order(unsigned long size) +{ + return __ilog2((size - 1) >> IOMMU_PAGE_SHIFT) + 1; +} + +#endif /* __ASSEMBLY__ */ + /* * IOMAP_MAX_ORDER defines the largest contiguous block * of dma space we can get. IOMAP_MAX_ORDER = 13 * allows up to 2**12 pages (4096 * 4096) = 16 MB */ -#define IOMAP_MAX_ORDER 13 +#define IOMAP_MAX_ORDER 13 struct iommu_table { unsigned long it_busno; /* Bus number this table belongs to */ -- cgit v1.2.3