android_kernel_motorola_sm6225/include/asm-powerpc/tce.h
Linas Vepstas 5d2efba64b [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>
2006-11-01 14:52:48 +11:00

50 lines
1.6 KiB
C

/*
* Copyright (C) 2001 Mike Corrigan & Dave Engebretsen, IBM Corporation
* Rewrite, cleanup:
* Copyright (C) 2004 Olof Johansson <olof@lixom.net>, IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _ASM_POWERPC_TCE_H
#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
*/
#define TCE_VB 0
#define TCE_PCI 1
/* TCE page size is 4096 bytes (1 << 12) */
#define TCE_SHIFT 12
#define TCE_PAGE_SIZE (1 << TCE_SHIFT)
#define TCE_ENTRY_SIZE 8 /* each TCE is 64 bits */
#define TCE_RPN_MASK 0xfffffffffful /* 40-bit RPN (4K pages) */
#define TCE_RPN_SHIFT 12
#define TCE_VALID 0x800 /* TCE valid */
#define TCE_ALLIO 0x400 /* TCE valid for all lpars */
#define TCE_PCI_WRITE 0x2 /* write from PCI allowed */
#define TCE_PCI_READ 0x1 /* read from PCI allowed */
#define TCE_VB_WRITE 0x1 /* write from VB allowed */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_TCE_H */