Bug#695182: linux-image-3.2.0-4-686-pae: Write couple of 1GB files for OOM crash
Dear Ben,
> Although PAE supports up to 64 GB RAM, everything the kernel accesses
> must be mapped into 1 GB of virtual address space (about 880 MB of
> persistently mapped 'normal memory', plus temporary mappings of the
> remaining 'high memory'). The use of such a large amount of high memory
> is problematic, though I don't know whether it entirely explains this
> behaviour. (The memory stats don't seem to account for much of the
> normal memory, as there is ~40 MB free but the various classes of
> allocations seem to add up to only ~300 MB.)
>
> These machines should all be installed with the amd64 kernel. Is there
> any reason you would prefer not to do that? Perhaps the kernel flavour
> selection in the installer should be changed to favour that based on the
> RAM size, though I'm not sure what the critical value should be.
Are you suggesting that the kernel lies, that 32-bit cannot handle 64GB?
Would it help to test the issue on a 16GB machine (I have one with
2*X5460 CPUs and one with single i5-3570), or with 24GB (have several
with 2*E5335 to 2*X5460)
I have seen recommendations to use 64-bit amd64. I am somewhat reluctant
on "jumping ship": I want continuity (when I upgrade by installing a
little more memory), want similarity between my various machines; and
have observed 32-bit being "faster" in some situations.
But really: this is a bug in the 32-bit build. Do I know that the same
or similar or worse bugs are not present also in the 64-bit build off
the same sources?
Thanks, Paul
Paul Szabo psz@maths.usyd.edu.au http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics University of Sydney Australia
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