How big should bigcore.core be?

Ulrich Weigand weigand@i1.informatik.uni-erlangen.de
Sun Apr 18 14:08:00 GMT 2004


Andrew Cagney wrote:

> > Cause of crash is that it allocates a couple of terabytes heap,
> > and then tries to coredump them; the Linux kernel coredump routines
> > do a full address space page-table walk, which insists on creating
> > all *page tables* visited, if not yet present.  For a couple of
> > terabytes address space, you need a couple of gigabytes page tables,
> > which are non-pagable kernel memory -- more real memory than my 
> > machine had ...
> 
> So it expands the page tables without actually allocating pages :-( 
> This would explain why, for amd64, it takes longer than I'd expect to 
> write out a 3mb phsyical (500gb virtual) core file -> kernel bug.

This should now be fixed with 2.6.6-rc1, see this changeset:
http://linux.bkbits.net:8080/linux-2.5/cset@407b10f6RDO7V1GsoQIrhiOWRJWPqA

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de



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