[linux-lvm] Discussion: performance issue on event activation mode

[Martin Wilck]

On Di, 2021-06-08 at 18:02 +0200, Zdenek Kabelac wrote:
> > 
> > > A third related improvement that could follow is to add stronger
> > > native
> > > mpath detection, in which lvm uses uses /etc/multipath/wwids,
> > > directly or
> > > through a multipath library, to identify mpath components.  This
> > > would
> > > supplement the existing sysfs and udev sources, and address the
> > > difficult
> > > case where the mpath device is not yet set up.
> > > 
> > Please don't. Use libmpathvalid if you want to improve in this
> > area.
> > That's what it was made for.
> 
> Problem is addition of another dependency here.
> 
> We may probably think about using  'dlopen' and if library is present
> use it, 
> but IMHO  libmpathvalid should be integrated into libblkid  in some
> way  - 
> linking another library to many other projects that needs to detect
> MP devices 
> really complicates this a lot.  libblkid should be able to decode
> this and 
> make things much cleaner.

Fair enough. I just wanted to say "don't start hardcoding anything new
in lvm2". Currently, you won't find libmpathvalid on many
distributions.

Martin