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| 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 /arch/powerpc/kernel/vio.c | |
| parent | dd6c89f686bdb2a5de72fab636fc839e5a0add6d (diff) | |
| download | linux-5d2efba64b231a1733c4048d1708d77e07f26426.tar.gz linux-5d2efba64b231a1733c4048d1708d77e07f26426.tar.bz2 linux-5d2efba64b231a1733c4048d1708d77e07f26426.zip | |
[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.c | 4 |
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; |