svn commit: r212360 - head/sys/vm

Alan Cox alc at rice.edu
Thu Sep 9 16:20:04 UTC 2010


Nathan Whitehorn wrote:
> Author: nwhitehorn
> Date: Thu Sep  9 13:32:58 2010
> New Revision: 212360
> URL: http://svn.freebsd.org/changeset/base/212360
>
> Log:
>   On architectures with non-tree-based page tables like PowerPC, every page
>   in a range must be checked when calling pmap_remove(). Calling
>   pmap_remove() from vm_pageout_map_deactivate_pages() with the entire range
>   of the map could result in attempting to demap an extraordinary number
>   of pages (> 10^15), so iterate through each map entry and unmap each of
>   them individually.
>   
>   

This is a machine-dependent issue, and so I will argue that it is the 
pmap's and not the machine-independent layer's responsibility to deal 
with this.  Our sparc64 port faces the same problem with the TSB, and it 
deals with it internally.  Moreover, the solution isn't that 
complicated.  Is there any reason why the sparc64 solution can't be 
applied to powerpc?

Regards,
Alan



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