On Mon, Nov 16, 2015 at 12:34:55PM -0800, Dan Williams wrote: > On Mon, Nov 16, 2015 at 11:48 AM, Ross Zwisler > <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > > On Mon, Nov 16, 2015 at 09:28:59AM -0800, Dan Williams wrote: > >> On Mon, Nov 16, 2015 at 6:05 AM, Jan Kara <jack@xxxxxxx> wrote: > >> > On Mon 16-11-15 14:37:14, Jan Kara wrote: > [..] > > Is there any reason why this wouldn't work or wouldn't be a good idea? > > We don't have numbers to support the claim that pcommit is so > expensive as to need be deferred, especially if the upper layers are > already taking the hit on doing the flushes. > > REQ_FLUSH, means flush your volatile write cache. Currently all I/O > through the driver never hits a volatile cache so there's no need to > tell the block layer that we have a volatile write cache, especially > when you have the core mm taking responsibility for doing cache > maintenance for dax-mmap ranges. > > We also don't have numbers on if/when wbinvd is a more performant solution. > > tl;dr Now that we have a baseline implementation can we please use > data to make future arch decisions? Sure, fair enough. -- 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>