On Wed, Mar 07, 2007 at 10:49:47AM +0100, Nick Piggin wrote: > On Wed, Mar 07, 2007 at 01:44:20AM -0800, Bill Irwin wrote: > > On Wed, Mar 07, 2007 at 10:28:21AM +0100, Nick Piggin wrote: > > > Depending on whether anyone wants it, and what features they want, we > > > could emulate the old syscall, and make a new restricted one which is > > > much less intrusive. > > > For example, if we can operate only on MAP_ANONYMOUS memory and specify > > > that nonlinear mappings effectively mlock the pages, then we can get > > > rid of all the objrmap and unmap_mapping_range handling, forget about > > > the writeout and msync problems... > > > > Anonymous-only would make it a doorstop for Oracle, since its entire > > motive for using it is to window into objects larger than user virtual > > Uh, duh yes I don't mean MAP_ANONYMOUS, I was just thinking of the shmem > inode that sits behind MAP_ANONYMOUS|MAP_SHARED. Of course if you don't > have a file descriptor to get a pgoff, then remap_file_pages is a doorstop > for everyone ;) > > > address spaces (this likely also applies to UML, though they should > > really chime in to confirm). Restrictions to tmpfs and/or ramfs would > > likely be liveable, though I suspect some things might want to do it to > > shm segments (I'll ask about that one). There's definitely no need for a > > persistent backing store for the object to be remapped in Oracle's case, > > in any event. It's largely the in-core destination and source of IO, not > > something saved on-disk itself. > > Yeah, tmpfs/shm segs are what I was thinking about. If UML can live with > that as well, then I think it might be a good option.
Oh, hmm.... if you can truncate these things then you still need to force unmap so you still need i_mmap_nonlinear. But come to think of it, I still don't think nonlinear mappings are too bad as they are ;) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
