> You can get up as much as 2gb if I heard other reports correctly. I am > using 1.5gb today. The exact limit is not known. It might depend on where > libraries are loaded. > > BTW, the higher this value is the lower is the number and size of files you > can have read/write at the same time. Every file that is read/written is > mapped into memory, too, and they all have to fit.
Marcus is confused here: we do not map all of the files into memory. Rather, we map a 64k window when we are doing I/O (cf. libpager/pager-memcpy.c). In other words, you will not run out of address space. Personally, I use file systems just under two GB; I would not try anything larger than that and it not only for the small address space that I take this precaution: I am worried about large positive numbers (i.e. greater than 2^31) breaking things. libihash, for instance, for instance, suffers from this.
