[Gluster-devel] optimizing gluster fuse

[riya khanna]

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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