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 --- arch/powerpc/sysdev/dart.h | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/powerpc/sysdev/dart.h') diff --git a/arch/powerpc/sysdev/dart.h b/arch/powerpc/sysdev/dart.h index 1c8817c4835..ff202edb059 100644 --- a/arch/powerpc/sysdev/dart.h +++ b/arch/powerpc/sysdev/dart.h @@ -72,7 +72,6 @@ #define DART_PAGE_SHIFT 12 #define DART_PAGE_SIZE (1 << DART_PAGE_SHIFT) -#define DART_PAGE_FACTOR (PAGE_SHIFT - DART_PAGE_SHIFT) #endif /* _POWERPC_SYSDEV_DART_H */ -- cgit v1.2.3