Change of Default kernel page size i.e 4KB

Change of Default kernel page size i.e 4KB

[naveen yadav]

Hi All,

I have few drivers and very big application running on ARM and MIPS target.
I want to check the performance by changing the page size ie.

8K, 16K, 32K etc.

Is it possile, If yes then what all care i need to take .

Thanks.

Re: Change of Default kernel page size i.e 4KB

[Ralf Baechle]

On Wed, Dec 01, 2010 at 01:50:13PM +0530, naveen yadav wrote:

> Cc: kernelnewbies@nl.linux.org,
> 	linux-arm-kernel-request@lists.arm.linux.org.uk,
                        ^^^^^^^^ WTF?
> 	linux-mips@linux-mips.org

> I have few drivers and very big application running on ARM and MIPS target.
> I want to check the performance by changing the page size ie.
> 
> 8K, 16K, 32K etc.
> 
> Is it possile, If yes then what all care i need to take .

For MIPS: Rebuild kernel with support for the new kernel size.  Few MIPS
cores.  Note that the `odd´ page sizes, that those that aren't a power
of 4 are only supported by Cavium while all MIPS III and newer processors
support even `even´ sizes 4KB, 16KB and 64KB.

Aside of rebuilding the kernel you also need a suitable userland; older
versions of binutils will produce binaries that only run
for 4kB page sizes.

For ARM the page size is fixed at 4kB which will simplify your benchmarking
efforts ;)

Performance gains very much depends on the workload but in general larger
sizes are beneficial except maybe for systems with very little memory.

  Ralf

Change of Default kernel page size i.e 4KB

[Ralf Baechle]

On Wed, Dec 01, 2010 at 01:50:13PM +0530, naveen yadav wrote:

> Cc: kernelnewbies at nl.linux.org,
> 	linux-arm-kernel-request at lists.arm.linux.org.uk,
                        ^^^^^^^^ WTF?
> 	linux-mips at linux-mips.org

> I have few drivers and very big application running on ARM and MIPS target.
> I want to check the performance by changing the page size ie.
> 
> 8K, 16K, 32K etc.
> 
> Is it possile, If yes then what all care i need to take .

For MIPS: Rebuild kernel with support for the new kernel size.  Few MIPS
cores.  Note that the `odd? page sizes, that those that aren't a power
of 4 are only supported by Cavium while all MIPS III and newer processors
support even `even? sizes 4KB, 16KB and 64KB.

Aside of rebuilding the kernel you also need a suitable userland; older
versions of binutils will produce binaries that only run
for 4kB page sizes.

For ARM the page size is fixed at 4kB which will simplify your benchmarking
efforts ;)

Performance gains very much depends on the workload but in general larger
sizes are beneficial except maybe for systems with very little memory.

  Ralf

Change of Default kernel page size i.e 4KB

[naveen yadav]

Hi all,

 I have few drivers and very big application running on ARM and MIPS target.
 I want to check the performance by changing the page size ie.
 8K, 16K, 32K etc.

 Is it possile, If yes then what all care i need to take .

thanks

RE: Change of Default kernel page size i.e 4KB

[Daniel Taylor]

 

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org 
> [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of naveen yadav
> Sent: Wednesday, December 01, 2010 8:53 AM
> To: linux-kernel@vger.kernel.org
> Subject: Change of Default kernel page size i.e 4KB
> 
> Hi all,
> 
>  I have few drivers and very big application running on ARM 
> and MIPS target.
>  I want to check the performance by changing the page size ie.
>  8K, 16K, 32K etc.
> 
>  Is it possile, If yes then what all care i need to take .
> 
> thanks
> --
> To unsubscribe from this list: send the line "unsubscribe 
> linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

For processor families that have Linux support for other-than-4K page
sizes, you can use menuconfig to change the page size in "Kernel Options".

This changes the configuration items: PPC_*_PAGES, SPARC64_PAGE_SIZE_*,
(MIPS) PAGE_SIZE_*, IA64_PAGE_SIZE_*.

RE: Change of Default kernel page size i.e 4KB

[Viral Mehta]

________________________________________
From: kernelnewbies-bounce@nl.linux.org [kernelnewbies-bounce@nl.linux.org] On Behalf Of naveen yadav
Hi,

>Hi All,
>
>I have few drivers and very big application running on ARM and MIPS target.
>I want to check the performance by changing the page size ie.

I remember it is possible on powerpc.
There is config option like CONFIG_PPC_64K_PAGES.
Not sure about ARM/MIPS archs, but you can certianly grep for something like 4K_PAGE all around defconfigs

>8K, 16K, 32K etc.
>
>Is it possile, If yes then what all care i need to take .
>
>Thanks.

--
Viral

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