Re: CVS commit: src

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Tue, Dec 24, 2013 at 04:19:18PM +0200, Mindaugas Rasiukevicius wrote:
> 
> Hence, I leaned towards not supporting the interface, instead of providing
> one which does not meet the expectations.  What do you think?

This is consistent with what Kirk McKusick and Keith Bostic told me many
years ago about CSRG's thinking on this issue (though of course at the
time the primitives in question were the System V, not the POSIX ones):
that the API is optional and is expected to be memory-backed, and that
users of the API would surely not expect disk-like latencies when it was
called; so if there was no memory filesystem available, the API should
not be provided.

However, this conflicts with the modern "portability" paradigm of doing
all feature tests at compile rather than runtime, so I'm a bit torn;
perhaps better to always mount a tmpfs on /var/shm at install time (or
even explicitly from an independent RC script?) but constrain its size
severely by system memory size at install time?

If we had a way to force tmpfs to page out aggressively when its memory
usage hit a threshold, rather than just having a hard limit on the size
of objects that could be created, that might be good for applications like
this one, no?