Re: [PATCH] pmem: export the symbols __copy_user_flushcache and __copy_from_user_flushcache

[Mikulas Patocka]

On Wed, 16 Sep 2020, Dan Williams wrote:

> On Wed, Sep 16, 2020 at 10:24 AM Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> >
> > > My first question about nvfs is how it compares to a daxfs with
> > > executables and other binaries configured to use page cache with the
> > > new per-file dax facility?
> >
> > nvfs is faster than dax-based filesystems on metadata-heavy operations
> > because it doesn't have the overhead of the buffer cache and bios. See
> > this: http://people.redhat.com/~mpatocka/nvfs/BENCHMARKS
> 
> ...and that metadata problem is intractable upstream? Christoph poked
> at bypassing the block layer for xfs metadata operations [1], I just
> have not had time to carry that further.
> 
> [1]: "xfs: use dax_direct_access for log writes", although it seems
> he's dropped that branch from his xfs.git

XFS is very big. I wanted to create something small.

Mikulas