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authorLinas Vepstas <linas@austin.ibm.com>2006-10-30 16:15:59 +1100
committerPaul Mackerras <paulus@samba.org>2006-11-01 14:52:48 +1100
commit5d2efba64b231a1733c4048d1708d77e07f26426 (patch)
tree2893dd45b9c26cef6cddb5fef0c6f820c5eb534e /arch/powerpc/kernel/vio.c
parentdd6c89f686bdb2a5de72fab636fc839e5a0add6d (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 'arch/powerpc/kernel/vio.c')
-rw-r--r--arch/powerpc/kernel/vio.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index cb87e71eec66..ed007878d1bf 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -92,9 +92,9 @@ static struct iommu_table *vio_build_iommu_table(struct vio_dev *dev)
&tbl->it_index, &offset, &size);
/* TCE table size - measured in tce entries */
- tbl->it_size = size >> PAGE_SHIFT;
+ tbl->it_size = size >> IOMMU_PAGE_SHIFT;
/* offset for VIO should always be 0 */
- tbl->it_offset = offset >> PAGE_SHIFT;
+ tbl->it_offset = offset >> IOMMU_PAGE_SHIFT;
tbl->it_busno = 0;
tbl->it_type = TCE_VB;