On Fri, Oct 30, 2015 at 04:37:36AM +0900, Dan Williams wrote: > [ reply-all re-send, sorry for the duplicate Jeff. ] > > On Thu, Oct 29, 2015 at 11:32 PM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: > > Hi, > > > > I'm concerned that applications that used to run out of page cache will > > experience a performance degradation when being forced into doing I/O > > directly to the backing store. What do others think? > > I would think this is only a problem in the case where the media is > orders of magnitude slower than page cache. That isn't the case with > pmem. If you're really concerned, I'm addressing this on XFS by making DAX per-inode selectable (i.e the mount option needs to die). In which case, users can have the best of both worlds - files marked as DAX use DAX/direct IO, files that aren't marked can cache and suffer the lower performance that all that page allocation, dirty tracking and writeback via memcpy entails.. 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
