linux-kernel - Re: Why half of slabs are not shown in /proc/slabinfo?

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Message-Id: <1245653782.18751.12.camel@penberg-laptop>
Date:	Mon, 22 Jun 2009 09:56:22 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Andrey Borzenkov <arvidjaar@...l.ru>
Cc:	linux-kernel@...r.kernel.org,
	Christoph Lameter <cl@...ux-foundation.org>,
	hugh.dickins@...cali.co.uk
Subject: Re: Why half of slabs are not shown in /proc/slabinfo?

On Sun, 2009-06-21 at 15:30 +0400, Andrey Borzenkov wrote:
> On Sunday 21 of June 2009 15:26:15 Pekka Enberg wrote:
> > On Sun, Jun 21, 2009 at 10:52 AM, Andrey Borzenkov<arvidjaar@...l.ru> 
> wrote:
> > > Mandriva kernel 2.6.30 using SLUB:
> > >
> > > {pts/1}% grep SLUB /boot/config
> > > CONFIG_SLUB_DEBUG=y
> > > CONFIG_SLUB=y
> > > # CONFIG_SLUB_DEBUG_ON is not set
> > > # CONFIG_SLUB_STATS is not set
> > >
> > > Some of slabs (e.g. filp) are not shown in /proc/slabinfo;
> > > comparing number of entries under /sys and slabinfo results in
> > >
> > > {pts/0}% =ls -1 /sys/kernel/slab | grep -v : | wc -l
> > > 131
> > > {pts/0}% wc -l /proc/slabinfo
> > > 68 /proc/slabinfo
> > > {pts/0}%
> > >
> > > so almost half of the all entries are missing. Is it expected or
> > > there is something wrong here?
> >
> > Can you post the actual file listing of /sys/kernel/slab and the
> > contents of /proc/slabinfo?
> 
> Sure.
> 
> {pts/1}% ls -l /sys/kernel/slab 

If you exclude all the symbolic links, the number of caches matches. As
Hugh already explained, SLUB merges caches which shows up like this in
the sysfs directory.

			Pekka

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