12:13 p.m.
[ adding Jan and Ross ]
On Wed, Jan 31, 2018 at 5:03 PM, Dan Williams <dan.j.williams(a)intel.com> wrote:
On Wed, Jan 31, 2018 at 4:45 PM, Andiry Xu <andiry(a)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 EXT4…)
> 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 “clean slate” 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 what’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