mmap changes, mostly for aout right now

Richard Stallman rms@gnu.ai.mit.edu
Tue Nov 7 09:39:00 GMT 1995


    On host systems where mmap is not available, you'll get a slight
    performance degradation compared with the older code.

I normally use a system which doesn't have mmap.
It seems to me that it ought to be easy to avoid any
performance loss on these systems
by simply using the old non-mmap code if mmap is not available.

Why not do this?

    Under Linux, using (a.out) object files read and stored over NFS, the
    performance got worse using mmap.  My guess is that this is a Linux
    problem.

This is a shame--it means this change actually does harm on today's
GNU systems.  We should not be making changes that help ONLY on non-GNU
systems and hurt GNU systems.

Can you please consult with Linux maintainers to see if this
is a bug in Linux that can be fixed straightforwardly?

If the slowness cannot be fixed soon in Linux, then please do
something in BFD to turn off use of mmap on Linux.  (This makes it
even more important to keep the performance of the non-mmap case as
good as it was before.)




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