Messages in this thread | | | Date | Wed, 26 Jul 2017 10:20:11 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v8 1/1] f2fs: dax: implement direct access |
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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.
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