On Fri, May 08, 2015 at 11:02:28PM -0400, Rik van Riel wrote: > On 05/08/2015 09:14 PM, Linus Torvalds wrote: > > On Fri, May 8, 2015 at 9:59 AM, Rik van Riel <riel@xxxxxxxxxx> wrote: > >> > >> However, for persistent memory, all of the files will be "in memory". > > > > Yes. However, I doubt you will find a very sane rw filesystem that > > then also makes them contiguous and aligns them at 2MB boundaries. > > > > Anything is possible, I guess, but things like that are *hard*. The > > fragmentation issues etc cause it to a really challenging thing. > > The TLB performance bonus of accessing the large files with > large pages may make it worthwhile to solve that hard problem. FWIW, for DAX ththe filesystem allocation side is already mostly solved - this is just an allocation alignment hint, analogous to RAID stripe alignment. We don't need to reinvent the wheel here. i.e. On XFS, use a 2MB stripe unit for the fs, a 2MB extent size hint for files you want to use large pages on and you'll get 2MB sized and aligned allocations from the filesystem for as long as there are such freespace regions available. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
