"Pinned" allocate

[N.M. Maclaren]

On Jan 5 2013, Janne Blomqvist wrote:
>On Thu, Jan 3, 2013 at 4:06 PM, Steve Kargl
>>
>> According to the FreeBSD man page, mlock and munlock are
>> available only to the superuser.  I suspect that this
>> restriction applies to other operating systems.
>
>On Linux the amount of memory an unprivileged user can lock is limited
>by the RLIMIT_MEMLOCK soft resource limit, which works like the other
>RLIMIT_ things (see e.g. limits.conf, ulimit, {get,set}rusage). That
>being said, needing to lock memory is a bit esoteric use case
>particularly for your typical Fortran program, so I think Thomas
>solution is preferable to adding yet another non-standard extension.

I would put it MUCH more strongly!  On many systems, whether memory is
'pinnable' (which is not as simple a concept as it seems) requires
specific system configuration, and not just privilege.  Inter alia,
it very often blocks the application from being swapped (which is why
superuser is needed).  And God alone knows how it interacts with the
high-RAS systems that support automatic memory migration upon ECC errors.

This isn't an appropriate level of concept for gfortran to consider;
please don't - not now, and not ever.


Regards,
Nick Maclaren.