Re: [Question] New mmap64 syscall?

Pavel Machek
2016-12-10T15:29:39Z

On Sat 2016-12-10 10:10:01, Pavel Machek wrote:
> Hi!
>
> > > Most of these advantages should eventually go away, when struct-reorg makes
> > > it way into the compiler. That said, it’s a marginal (but real) improvement for a
> > > subset of SPEC.
> > >
> > > In the real world, the importance of ILP32 as an aid to transition legacy code
> > > that is not 64bit clean… and this should drive the ILP32 discussion. That we
> > > get a boost in our SPEC scores is just a nice extra that we get from it
> >
> > To bring this back from the philosophical questions of ABI design
> > to the specific point of what file offset width you want for mmap()
> > on 32-bit architectures.
> >
> > For all I can tell, using mmap() to access a file that is many thousand
> > times larger than your virtual address space is completely crazy.
>
> Dunno. Wanting to mmap part of a partition does not seem too crazy... I'm pretty
> sure there's some tool out there that uses mmap(), just because mmap() was nicer
> to use then read(). And when the partition is big, the offset may be big.

Actually, if I wrote something like jpegrecover, I'd use mmap() for that (because
otherwise I'd be keeping copy of disk in anonymous memory, increasing memory pressure).

jpegrecover definitely makes sense on partitions...

Pavel
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