Re: [RFC PATCH] ceph: add remote object copy counter to fs client

[Jeff Layton]

On Thu, 2021-10-21 at 09:52 -0400, Patrick Donnelly wrote:
> On Wed, Oct 20, 2021 at 12:27 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> > 
> > On Wed, 2021-10-20 at 15:37 +0100, Luís Henriques wrote:
> > > This counter will keep track of the number of remote object copies done on
> > > copy_file_range syscalls.  This counter will be filesystem per-client, and
> > > can be accessed from the client debugfs directory.
> > > 
> > > Cc: Patrick Donnelly <pdonnell@xxxxxxxxxx>
> > > Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
> > > ---
> > > This is an RFC to reply to Patrick's request in [0].  Note that I'm not
> > > 100% sure about the usefulness of this patch, or if this is the best way
> > > to provide the functionality Patrick requested.  Anyway, this is just to
> > > get some feedback, hence the RFC.
> > > 
> > > Cheers,
> > > --
> > > Luís
> > > 
> > > [0] https://github.com/ceph/ceph/pull/42720
> > > 
> > 
> > I think this would be better integrated into the stats infrastructure.
> > 
> > Maybe you could add a new set of "copy" stats to struct
> > ceph_client_metric that tracks the total copy operations done, their
> > size and latency (similar to read and write ops)?
> 
> I think it's a good idea to integrate this into "stats" but I think a
> local debugfs file for some counters is still useful. The "stats"
> module is immature at this time and I'd rather not build any qa tests
> (yet) that rely on it.
> 
> Can we generalize this patch-set to a file named "op_counters" or
> similar and additionally add other OSD ops performed by the kclient?
> 


Tracking this sort of thing is the main purpose of the stats code. I'm
really not keen on adding a whole separate set of files for reporting
this. 

What's the specific problem with relying on the data in debugfs
"metrics" file?


-- 
Jeff Layton <jlayton@xxxxxxxxxx>