Re: [GIT PULL] PMEM driver for v4.1

From: Christoph Hellwig
Date: Mon Apr 13 2015 - 05:35:48 EST


On Mon, Apr 13, 2015 at 11:33:09AM +0200, Ingo Molnar wrote:
> Limitations: this is a regular block device, and since the pmem areas
> are not struct page backed, they are invisible to the rest of the
> system (other than the block IO device), so direct IO to/from pmem
> areas, direct mmap() or XIP is not possible yet. The page cache will
> also shadow and double buffer pmem contents, etc.

Unless you use the DAX support in ext2/4 and soon XFS, in which case
we avoid that double buffering when doing read/write and mmap
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