linux-kernel - v4.9, 4.4-final: 28 bioset threads on small notebook, 36 threads on cellphone

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Message-ID: <20170206125309.GA29395@amd>
Date:   Mon, 6 Feb 2017 13:53:09 +0100
From:   Pavel Machek <pavel@....cz>
To:     Mike Snitzer <snitzer@...hat.com>, kent.overstreet@...il.com
Cc:     kernel list <linux-kernel@...r.kernel.org>, axboe@...com,
        hch@....de, kent.overstreet@...il.com, neilb@...e.de,
        martin.petersen@...cle.com, dpark@...teo.net,
        ming.l@....samsung.com, dm-devel@...hat.com,
        ming.lei@...onical.com, agk@...hat.com, jkosina@...e.cz,
        geoff@...radead.org, jim@...n.com, pjk1939@...ux.vnet.ibm.com,
        minchan@...nel.org, ngupta@...are.org, oleg.drokin@...el.com,
        andreas.dilger@...el.com
Subject: v4.9, 4.4-final: 28 bioset threads on small notebook, 36 threads on
 cellphone

On Sat 2016-02-20 21:04:32, Pavel Machek wrote:
> 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@...il.com> is to blame.
> 
> Um, and you acked the patch, so you are partly responsible.

Still there on v4.9, 36 threads on nokia n900 cellphone.

So.. what needs to be done there?
									Pavel

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

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