On Thu, 29 Nov 2012, Jeff Moyer wrote: > Dave Kleikamp <dave.kleikamp@xxxxxxxxxx> writes: > > >> 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 > > > > As the patches exist today, the loop driver will only make the aio calls > > if the underlying file defines a direct_IO address op since > > generic_file_read/write_iter() will call a_ops->direct_IO() when > > O_DIRECT is set. For tmpfs or any other filesystem that doesn't support > > O_DIRECT, the loop driver will continue to call the read() or write() > > method. > > Hi, Hugh and Shaggy, > > Thanks for your replies--it looks like we're back to square one. I > think it would be trivial to add O_DIRECT support to tmpfs, but I'm not > convinced it's necessary. Should we wait until bug reports start to > come in? It's reassuring to know that tmpfs won't have to rush in direct_IO to support loop when Dave's changes go through (thanks); but I'd still like to experiment with going that way, to see if it works better. I've not been entirely convinced that tmpfs needs direct_IO either; but your links from back then show a number of people who feel that direct_IO had become mainstream enough to deserve the appearance of support by tmpfs. And you observe that tmpfs is being used more widely for /tmp nowadays: I agree that may increase its desirability. Like you, I'm really hoping someone will join in and say they'd been disadvantaged by lack of O_DIRECT on tmpfs: no strong feeling myself. 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>