Re: [RFC] Hugetlb demotion for x86

[Adam Litke]

On Wed, 2006-05-10 at 21:05 +0100, Christoph Hellwig wrote:
> On Wed, May 10, 2006 at 01:56:40PM -0500, Adam Litke wrote:
> > The following patch enables demotion of MAP_PRIVATE hugetlb memory to
> > normal anonymous memory on the i386 architecture.
> 
> This is an awfully bad idea.  Applications should do smart fallback
> instead.  For the same reason we for example fail O_DIRECT requests
> we can fullfill instead of doing the half buffered I/O braindamage
> solaris does.

By smart fallback do you mean we should convert the hugetlb fault code
back to using VM_FAULT_SIGBUS and writing userspace sighandlers to do
the same thing I am, but in userspace?  FWIW I did implement that in
libhugetlbfs to try it out, but that seems much dirtier to me than
handling faults in the kernel.

-- 
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

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