diff options
| author | Ilya Yanok <yanok@emcraft.com> | 2008-12-11 04:55:41 +0300 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2008-12-29 09:53:25 +1100 |
| commit | ca9153a3a2a7556d091dfe080e42b0e67881fff6 (patch) | |
| tree | 35b5ce24f190690cf7a726cbb97980da51704855 /arch/powerpc/Kconfig | |
| parent | 6ca4f7494bde078b2b730e28e4ea1dc36a772f70 (diff) | |
powerpc/44x: Support 16K/64K base page sizes on 44x
This adds support for 16k and 64k page sizes on PowerPC 44x processors.
The PGDIR table is much smaller than a page when using 16k or 64k
pages (512 and 32 bytes respectively) so we allocate the PGDIR with
kzalloc() instead of __get_free_pages().
One PTE table covers rather a large memory area when using 16k or 64k
pages (32MB or 512MB respectively), so we can easily put FIXMAP and
PKMAP in the area covered by one PTE table.
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Vladimir Panfilov <pvr@emcraft.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/Kconfig')
| -rw-r--r-- | arch/powerpc/Kconfig | 58 |
1 files changed, 44 insertions, 14 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index f7f5448f863d..1af22579e3d4 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -405,23 +405,53 @@ config PPC_HAS_HASH_64K depends on PPC64 default n -config PPC_64K_PAGES - bool "64k page size" - depends on PPC64 - select PPC_HAS_HASH_64K +choice + prompt "Page size" + default PPC_4K_PAGES help - This option changes the kernel logical page size to 64k. On machines - without processor support for 64k pages, the kernel will simulate - them by loading each individual 4k page on demand transparently, - while on hardware with such support, it will be used to map - normal application pages. + Select the kernel logical page size. Increasing the page size + will reduce software overhead at each page boundary, allow + hardware prefetch mechanisms to be more effective, and allow + larger dma transfers increasing IO efficiency and reducing + overhead. However the utilization of memory will increase. + For example, each cached file will using a multiple of the + page size to hold its contents and the difference between the + end of file and the end of page is wasted. + + Some dedicated systems, such as software raid serving with + accelerated calculations, have shown significant increases. + + If you configure a 64 bit kernel for 64k pages but the + processor does not support them, then the kernel will simulate + them with 4k pages, loading them on demand, but with the + reduced software overhead and larger internal fragmentation. + For the 32 bit kernel, a large page option will not be offered + unless it is supported by the configured processor. + + If unsure, choose 4K_PAGES. + +config PPC_4K_PAGES + bool "4k page size" + +config PPC_16K_PAGES + bool "16k page size" if 44x + +config PPC_64K_PAGES + bool "64k page size" if 44x || PPC_STD_MMU_64 + select PPC_HAS_HASH_64K if PPC_STD_MMU_64 + +endchoice config FORCE_MAX_ZONEORDER int "Maximum zone order" - range 9 64 if PPC_64K_PAGES - default "9" if PPC_64K_PAGES - range 13 64 if PPC64 && !PPC_64K_PAGES - default "13" if PPC64 && !PPC_64K_PAGES + range 9 64 if PPC_STD_MMU_64 && PPC_64K_PAGES + default "9" if PPC_STD_MMU_64 && PPC_64K_PAGES + range 13 64 if PPC_STD_MMU_64 && !PPC_64K_PAGES + default "13" if PPC_STD_MMU_64 && !PPC_64K_PAGES + range 9 64 if PPC_STD_MMU_32 && PPC_16K_PAGES + default "9" if PPC_STD_MMU_32 && PPC_16K_PAGES + range 7 64 if PPC_STD_MMU_32 && PPC_64K_PAGES + default "7" if PPC_STD_MMU_32 && PPC_64K_PAGES range 11 64 default "11" help @@ -441,7 +471,7 @@ config FORCE_MAX_ZONEORDER config PPC_SUBPAGE_PROT bool "Support setting protections for 4k subpages" - depends on PPC_64K_PAGES + depends on PPC_STD_MMU_64 && PPC_64K_PAGES help This option adds support for a system call to allow user programs to set access permissions (read/write, readonly, or no access) |