> I can easily replace the mmap-memcpy with pread/pwrite. Unfortunately I > see huge performance drops if I do so. Currently I'm looking why the system > call variant costs so much more than mmap.
An alternative approach would be to mmap *only* the minidisk label and FST on access of the minidisk, and then mmap individual files as you need them. I'm not objecting to the use of mmap, just the gratuitous use of mmap on the whole disk rather than what you actually *need* at that moment. It's like the old Antonin Chekov quote about what's necessary in a play: if there's a pistol on stage, you need to have killed someone by act II, scene 1. Otherwise, take it out -- it didn't need to be there.
