Re: [RFC PATCH v2 00/12] Introduce the famfs shared-memory file system

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On Mon, Apr 29, 2024 at 09:24:19PM -0500, John Groves wrote:
> On 24/04/29 07:08PM, Kent Overstreet wrote:
> > On Mon, Apr 29, 2024 at 07:32:55PM +0100, Matthew Wilcox wrote:
> > > On Mon, Apr 29, 2024 at 12:04:16PM -0500, John Groves wrote:
> > > > This patch set introduces famfs[1] - a special-purpose fs-dax file system
> > > > for sharable disaggregated or fabric-attached memory (FAM). Famfs is not
> > > > CXL-specific in anyway way.
> > > > 
> > > > * Famfs creates a simple access method for storing and sharing data in
> > > >   sharable memory. The memory is exposed and accessed as memory-mappable
> > > >   dax files.
> > > > * Famfs supports multiple hosts mounting the same file system from the
> > > >   same memory (something existing fs-dax file systems don't do).
> > > 
> > > Yes, but we do already have two filesystems that support shared storage,
> > > and are rather more advanced than famfs -- GFS2 and OCFS2.  What are
> > > the pros and cons of improving either of those to support DAX rather
> > > than starting again with a new filesystem?
> > 
> > I could see a shared memory filesystem as being a completely different
> > beast than a shared block storage filesystem - and I've never heard
> > anyone talking about gfs2 or ocfs2 as codebases we particularly liked.
> Thanks for your attention on famfs, Kent.
> I think of it as a completely different beast. See my reply to Willy re:
> famfs being more of a memory allocator with the benefit of allocations 
> being accessible (and memory-mappable) as files.

That's pretty much what I expected.

I would suggest talking to RDMA people; RDMA does similar things with
exposing address spaces across machine, and an "external" memory
allocator is a basic building block there as well - it'd be great if we
could get that turned into some clean library code.

GPU people as well, possibly.

> The famfs user space repo has some good documentation as to the on-
> media structure of famfs. Scroll down on [1] (the documentation from
> the famfs user space repo). There is quite a bit of info in the docs
> from that repo.

Ok, looking through that now.

So youv've got a metadata log; that looks more like a conventional
filesystem than a conventional purely in-memory thing.

But you say it's a shared filesystem, and it doesn't say anything about
that. Inter node locking?

Perhaps the ocfs2/gfs2 comparison is appropriate, after all.

[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux