[PATCH] UBI: Add volume read and write statistics

[per.forlin@xxxxxxxx (Per Förlin)]

Thanks Richard for your feedback,

> ________________________________________
> From: Richard Weinberger <richard at nod.at>
> Sent: Tuesday, July 17, 2018 4:34 PM
> To: Per F?rlin
> Cc: linux-mtd at lists.infradead.org; Artem Bityutskiy
> Subject: Re: [PATCH] UBI: Add volume read and write statistics
> 
> Per,
> 
> Am Dienstag, 17. Juli 2018, 14:08:51 CEST schrieb Per F?rlin:
> > > To: Per F?rlin
> > > Cc: linux-mtd at lists.infradead.org; Artem Bityutskiy; Per F?rlin
> > > Subject: Re: [PATCH] UBI: Add volume read and write statistics
> > >
> > > Am Dienstag, 17. Juli 2018, 12:30:19 CEST schrieb Per Forlin:
> > > > Simple read and write statistics.
> > > > * Bytes read
> > > > * Bytes written
> > > > * Number of reads
> > > > * Number of writes
> > > >
> > > > This is useful to find out how the storage is being utilized.
> > > > For block devices this already exists via /proc/diskstats.
> > > > The intention of this patch is to add similar stats
> > > > for UBI as well.
> > >
> > > Why on UBI level and not MTD?
> > In my case I wanted to evaluate the performance per volume. I have one MTD
> > device with several UBI volumes. It would be sufficient to have it on
> > an MTD level to see the overall storage usage.
> > This would still be very helpful for me.
> >
> > Having it on an MTD level is of course more general.
> > I wouldn't mind changing the patch to add the stats in mtdcore
> > for mtd_read() and mtd_write()
> >
> > In case of MTD block devices the stats will be somewhat redundant with
> > /proc/diskstats.
> >
> > Do you think I should update the patch to add MTD stats instead?
> 
> While having a cup of coffee I thought more about this.
> Actually both, MTD and UBI makes sense.
> The most important issue is that you integrate it with the existing diskstats.
> So instead of having our own interface feeding MTD/UBI stats into diskstats
> would be nice. Did you look into that? I'm not sure how much work this would be.
> That way users can use existing tools such as iostat...
I actually started out looking for the information under diskstats,
then I learned it's only for block devices. I took a quick glance at
it before I went for the sys implementation instead. diskstats is
separated from the MTD and UBI stuff and I don't know if one can make a
connection to MTD/UBI somehow. I will take a closer look at this.