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Re: How big should bigcore.core be?
- From: Ulrich Weigand <weigand at i1 dot informatik dot uni-erlangen dot de>
- To: cagney at gnu dot org (Andrew Cagney)
- Cc: weigand at i1 dot informatik dot uni-erlangen dot de (Ulrich Weigand), kettenis at chello dot nl, gdb at sources dot redhat dot com
- Date: Sun, 18 Apr 2004 02:16:26 +0200 (CEST)
- Subject: Re: How big should bigcore.core be?
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