Re: [naviserver-devel] uploading large files

[Zoran V. <zv...@ar...>]

Am 17.06.2005 um 09:24 schrieb Stephen Deasey:

>
> I believe this is pretty common, but I'm not sure if this is what you
> want.  An anonymous mapping is still going to account against the
> processes memory budget, and I don't think it's going to be any more
> likely to be swapped out than malloc'ed memory.
>
> In fact, on Linux (well, glibc) if you ask malloc for a chunk of
> memory over a certain size then mmap is used internally.  I think the
> advantage is reduced memory fragmentation, but there is some overhead
> for small sizes and you have to allocate in multiples of the page size
> (4k).
>
> tempfs would be a better bet.  Modern Linux systems have this mounted
> at /dev/shm.  I think this is a Solaris thing.  This is a very low
> overhead file system where the file data springs into existence when
> you ask for it.  So, no files, no overhead.  Under memory pressure
> it's sent to swap.  It was designed for sharing memory between
> processes using mmap, but it's handy for /tmp and some other things.
>
> You could try setting the TMPDIR environment variable to some tempfs
> file system if you wanted to experiment with this.

Not to forget: Darwin, Windows... I think I will have to find a
common acceptable solution for all OS'es. Fortunately, mapping
a regular (temp) file will always work. The rest is just optimizations.

Cheers
Zoran