On Wed, Jul 26, 2017 at 10:11:08AM -0700, Dan Williams wrote: > Until HMAT came along we had no data in the kernel how to pick a sane > default, but we could now very easily make a "if pmem performance < > dram, disable dax by default" policy in the kernel.
I'd rather do it the other way around - if HMAT is present and pmem performance >= dram use dax. Else require the explicit -o dax for now to enable it. If an explicit -o nodax is specified disable DAX even if HMAT says it is faster. > The question for this patch is do we want to add yet another > filesystem that adds "-o dax" or require use of per-inode flags to > enable dax. Please stick to the mount option. After spending a lot of time with DAX and various memory techologies I'm pretty confident that the inode flag is the wrong thing to do.
