svn commit: r221855 - in head/sys: amd64/include arm/include dev/md dev/null i386/include ia64/include mips/include powerpc/include sparc64/include sun4v/include sys vm

[Alan Cox]

On 5/13/2011 2:35 PM, Matthew D Fleming wrote:
> Author: mdf
> Date: Fri May 13 19:35:01 2011
> New Revision: 221855
> URL: http://svn.freebsd.org/changeset/base/221855
>
> Log:
>    Move the ZERO_REGION_SIZE to a machine-dependent file, as on many
>    architectures (i386, for example) the virtual memory space may be
>    constrained enough that 2MB is a large chunk.  Use 64K for arches
>    other than amd64 and ia64, with special handling for sparc64 due to
>    differing hardware.
>
>    Also commit the comment changes to kmem_init_zero_region() that I
>    missed due to not saving the file.  (Darn the unfamiliar development
>    environment).
>
>    Arch maintainers, please feel free to adjust ZERO_REGION_SIZE as you
>    see fit.
>
>    Requested by:	alc
>    MFC after:	1 week
>    MFC with:	r221853

I would encourage people on platforms with virtually indexed data caches 
to do a simple before and after performance test on this change, like 
"dd if=/dev/zero of=/dev/null bs=64k", just to make sure that there are 
no performance regressions.

Alan