On Tue, 27 Nov 2012, Jeff Moyer wrote: > Hi Hugh and others, > > In 2007, there were some discussions on whether to allow opens to > specify O_DIRECT for files backed by tmpfs.[1][2] On the surface, it > sounds like a completely crazy thing to do. However, distributions like > Fedora are now defaulting to using a tmpfs /tmp. I'm not aware of any > applications that open temp files using O_DIRECT, but I wanted to get > some new discussion going on whether this is a reasonable thing to > expect to work. > > Thoughts? > > Cheers, > Jeff > > [1] https://lkml.org/lkml/2007/1/4/55 > [2] http://thread.gmane.org/gmane.linux.kernel/482031 Thanks a lot for refreshing my memory with those links. Whilst I agree with every contradictory word I said back then ;) my current position is to wait to see what happens with Shaggy's "loop: Issue O_DIRECT aio using bio_vec" https://lkml.org/lkml/2012/11/22/847 I've been using loop on tmpfs-file in testing for years, and will not allow that to go away. I've not yet tried applying the patches and fixing up mm/shmem.c to suit, but will make sure that it's working before a release emerges with those changes in. It would be possible to add nominal O_DIRECT support to tmpfs without that, and perhaps it would be possible to add that loop support without enabling O_DIRECT from userspace; but my inclination is to make those changes together. (I'm not thinking of doing ramfs and hugetlbfs too.) Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>