Re: [LSF/MM TOPIC] Native NVMM file systems

[Jan Kara <jack@suse.cz>]

On Wed 31-01-18 17:13:37, Dan Williams wrote:
> [ adding Jan and Ross ]
> 
> On Wed, Jan 31, 2018 at 5:03 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > On Wed, Jan 31, 2018 at 4:45 PM, Andiry Xu <andiry@gmail.com> wrote:
> >> PMEM/DAX should allow for significant improvements in file system
> >> performance and enable new programming models that allow direct,
> >> efficient access to PMEM from userspace.  Achieving these gains in
> >> existing file systems built for block devices (e.g., XFS and EXT4a?|)
> >> presents a range of challenges (e.g.,
> >> https://lkml.org/lkml/2016/9/11/159) and has been the subject of a lot
> >> of recent work on ext4 and xfs.
> >>
> >> An alternative is to build a NVMM-aware file system from scratch that
> >> takes full advantage of the performance that PMEM offers and avoids
> >> the complexity that block-based file systems include to maximize
> >> performance on slow storage (e.g., relaxing atomicity constraints on
> >> many operations).  Of course, it also brings with it the complexity of
> >> another file system.
> >>
> >> We recently sent out a patch set for one-such a??clean slatea?? NVMM-aware
> >> file system called NOVA.  NOVA is log-structured DAX file system with
> >> several nice features:
> >>
> >> * High performance, especially in metadata operations due to efficient
> >> fine-grained logging
> >> * High scalability with per-CPU memory pool and per-inode logging
> >> * Strong metadata and data atomicity guarantees for all operations
> >> * Full filesystem snapshot support with DAX-mmap
> >> * Metadata replication/checksums and RAID-4 style data protection
> >>
> >> At the summit, we would like to discuss the trade-offs between
> >> adapting NVMM features to existing file systems vs. creating/adopting
> >> a purpose-built file system for NVMM.  NOVA serves as useful starting
> >> point for that discussion by demonstrating whata??s possible.  It may
> >> also suggest some features that could be adapted to other file systems
> >> to improve NVMM performance.
> >>
> >> We welcome people that are interested in file systems and NVM/DAX.
> >> Particular people that would be useful to have in attendance are Dan
> >> Williams, Dave Chinner, and Matthew Wilcox.
> >
> > The rest of the fs-dax crew would also be useful to have:
> >
> > Jan Kara
> > Ross Zwisler

Thanks Dan. Yes, I'd be interested in discussions about NOVA. In fact I
guess the biggest obstacle is currently the review bandwidth. New
filesystem is a substantial chunk of code and although it does not have to
be perfect to include it in the kernel it still needs at least some basic
review...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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