Re: [PATCH] bugfix dax fault page should be no cache

From: Matthew Wilcox
Date: Wed Jan 13 2016 - 11:32:36 EST


On Wed, Jan 13, 2016 at 11:47:12AM +0800, Chenjie (K) wrote:
> The DAX means Direct Access for filesïif the pages have cache,
> the file is not direct access. But in normal condition,
> we can not find the problem directly.

The file absolutely is direct accessed. The CPU cache is critical to
performance, and should not be bypassed lightly. We have instructions to
flush the cache, and a library (see http://pmem.io/) so that applications
don't have to use them directly.