Re: [PATCH] fuse: cleanup request queuing towards virtiofs

[Peter-Jan Gootzen <pgootzen@nvidia.com>]

On Wed, 2024-05-29 at 14:32 -0400, Stefan Hajnoczi wrote:
> On Wed, May 29, 2024 at 05:52:07PM +0200, Miklos Szeredi wrote:
> > Virtiofs has its own queing mechanism, but still requests are first
> > queued
> > on fiq->pending to be immediately dequeued and queued onto the
> > virtio
> > queue.
> > 
> > The queuing on fiq->pending is unnecessary and might even have some
> > performance impact due to being a contention point.
> > 
> > Forget requests are handled similarly.
> > 
> > Move the queuing of requests and forgets into the fiq->ops->*.
> > fuse_iqueue_ops are renamed to reflect the new semantics.
> > 
> > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> > ---
> >  fs/fuse/dev.c       | 159 ++++++++++++++++++++++++-----------------
> > ---
> >  fs/fuse/fuse_i.h    |  19 ++----
> >  fs/fuse/virtio_fs.c |  41 ++++--------
> >  3 files changed, 106 insertions(+), 113 deletions(-)
> 
> This is a little scary but I can't think of a scenario where directly
> dispatching requests to virtqueues is a problem.
> 
> Is there someone who can run single and multiqueue virtiofs
> performance
> benchmarks?

Yes we can provide that with our BlueField DPU setup. I will review,
test and perform some experiments on the patch and get back to you all
on this with some numbers.

> 
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

- Peter-Jan