[Gluster-devel] optimizing gluster fuse

riya khanna riyakhanna1983 at gmail.com
Mon Apr 2 14:57:12 UTC 2018

Thanks Amar! Please see my answers inline.

On Mon, Apr 2, 2018 at 5:41 AM, Amar Tumballi <atumball at redhat.com> wrote:

> Hi Riya,
> Thanks for writing to us. Some questions before we start on this.
> * Where can we see your work of modifying the fuse module to cache the
> calls? Some reference would help us to provide more specific pointers. (or
> ask better questions).
> I've created a fast path framework for FUSE, where the user space daemon
can load a module and register handlers for file operations (lookup, open,
r/w, etc.) that must be handled in the kernel itself without an up call to
the user space. I call them fast path handlers. This design also retains
the regular FUSE handlers for file system operations in upser-space (slow
path). The fast path and slow path can communicate with each other over
shared memory or using  syscalls to enable/invalidate caching of data
structs (e.g., results of getattr, getxattr, etc.)

There's a process I need to follow in order to make the code available
publicly. I've already started, but will take some time. I will try to do
this asap.

* If the caching happened in fuse module, and it expects the regular
> arguments as the parameters, then there may not be any work required at all
> in glusterfs, as it works on low-level fuse api.
The fast handlers expect same interface and args (fuse_args) as the regular
user-space daemon. The fast handler code is fs-specific, therefore, must
come from glusterfs. Changes are also needed in glusterfs code to
communicate with the fast path for enabling/invalidating caching.

> * Also, how to invalidate caches from userspace program? because GlusterFS
> could be accessed from multiple clients, so it becomes an important piece
> to have.
Server invalidate can trigger a system call into the fast path framework to
invalidate caches.

> For referring at the codebase to look at integration with fuse module,
> please check the directory 'xlators/mount/fuse/src/' and mostly the file
> 'fuse-bridge.c'.
> Thanks for your interest in project, would be great to collaborate on this
> effort, as it can enhance the performance of glusterfs in many usecases.

I'm still going through gluster developer documentation, but it'd be
helpful if you could mention what kind of use cases does the fast/slow
split FUSE framework enable? i've already applied the framework to
accelerate multiple FUSE-based stackable file systems, but want the
interface to be generic enough for all FUSE file systems to take advantage
of it.

> Regards,
> Amar
> On Mon, Apr 2, 2018 at 6:34 AM, riya khanna <riyakhanna1983 at gmail.com>
> wrote:
>> Hi,
>> I've modified FUSE framework to take a part of user-space daemon code and
>> moves it into the kernel fuse driver to minimize user-kernel-user switches
>> during file system  operations. An example would be caching
>> getattr/getxattr/lookup/security checks etc. This design, therefore,
>> create fast (served directly from the kernel) and a slow (regular fuse)
>> execution paths. The fast and slow paths can also communicate with each
>> other using shared memory.
>> I was wondering if it is possible to accelerate glusterfs using this
>> design. What pieces could (should) be easily moved to kernel space? Any
>> pointers would be highly appreciated. Thanks!
>> -Riya
>> _______________________________________________
>> Gluster-devel mailing list
>> Gluster-devel at gluster.org
>> http://lists.gluster.org/mailman/listinfo/gluster-devel
> --
> Amar Tumballi (amarts)
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