diff options
| author | Linas Vepstas <linas@austin.ibm.com> | 2006-10-30 16:15:59 +1100 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2006-11-01 14:52:48 +1100 |
| commit | 5d2efba64b231a1733c4048d1708d77e07f26426 (patch) | |
| tree | 2893dd45b9c26cef6cddb5fef0c6f820c5eb534e /include | |
| parent | dd6c89f686bdb2a5de72fab636fc839e5a0add6d (diff) | |
[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 <linas@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-powerpc/iommu.h | 22 | ||||
| -rw-r--r-- | include/asm-powerpc/tce.h | 3 |
2 files changed, 22 insertions, 3 deletions
diff --git a/include/asm-powerpc/iommu.h b/include/asm-powerpc/iommu.h index a5e98641a2ae..39fad685ffab 100644 --- a/include/asm-powerpc/iommu.h +++ b/include/asm-powerpc/iommu.h @@ -22,17 +22,35 @@ #define _ASM_IOMMU_H #ifdef __KERNEL__ -#include <asm/types.h> +#include <linux/compiler.h> #include <linux/spinlock.h> #include <linux/device.h> #include <linux/dma-mapping.h> +#include <asm/types.h> +#include <asm/bitops.h> + +#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 */ diff --git a/include/asm-powerpc/tce.h b/include/asm-powerpc/tce.h index c9483adbf599..f663634cccc9 100644 --- a/include/asm-powerpc/tce.h +++ b/include/asm-powerpc/tce.h @@ -22,6 +22,8 @@ #define _ASM_POWERPC_TCE_H #ifdef __KERNEL__ +#include <asm/iommu.h> + /* * Tces come in two formats, one for the virtual bus and a different * format for PCI @@ -33,7 +35,6 @@ #define TCE_SHIFT 12 #define TCE_PAGE_SIZE (1 << TCE_SHIFT) -#define TCE_PAGE_FACTOR (PAGE_SHIFT - TCE_SHIFT) #define TCE_ENTRY_SIZE 8 /* each TCE is 64 bits */ |