[dm-devel] 4.4-final: 28 bioset threads on small notebook

[Pavel Machek]

Hi!

> > > > > I know it is normal to spawn 8 threads for every single function,
> > > > ...
> > > > > but 28 threads?
> > > > > 
> > > > > root       974  0.0  0.0      0     0 ?        S<   Dec08   0:00 [bioset]
> > > > ...
> > > > 
> > > > How many physical block devices do you have?
> > > > 
> > > > DM is doing its part to not contribute to this:
> > > > dbba42d8a ("dm: eliminate unused "bioset" process for each bio-based DM device")
> > > > 
> > > > (but yeah, all these extra 'bioset' threads aren't ideal)
> > > 
> > > Still there in 4.4-final.
> > 
> > ...and still there in 4.5-rc4 :-(.
> 
> You're directing this concern to the wrong person.
> 
> I already told you DM is _not_ contributing any extra "bioset" threads
> (ever since commit dbba42d8a).

Well, sorry about that. Note that l-k is on the cc list, so hopefully
the right person sees it too.

Ok, let me check... it seems that 
54efd50bfd873e2dbf784e0b21a8027ba4299a3e is responsible, thus Kent
Overstreet <kent.overstreet at gmail.com> is to blame.

Um, and you acked the patch, so you are partly responsible.

> But in general, these "bioset" threads are a side-effect of the
> late-bio-splitting support.  So is your position on it: "I don't like
> that feature if it comes at the expense of adding resources I can _see_
> for something I (naively?) view as useless"?

> Just seems... naive... but you could be trying to say something else
> entirely.

> Anyway, if you don't like something: understand why it is there and then
> try to fix it to your liking (without compromising why it was there to
> begin with).

Well, 28 kernel threads on a notebook is a bug, plain and simple. Do
you argue it is not?

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html