linux-kernel - Re: [PATCH 3/7] slub: Do not use c->page on free

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Message-ID: <20141216161521.1f72e102@redhat.com>
Date:	Tue, 16 Dec 2014 16:15:21 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	akpm@...uxfoundation.org, rostedt@...dmis.org,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Pekka Enberg <penberg@...nel.org>, brouer@...hat.com
Subject: Re: [PATCH 3/7] slub: Do not use c->page on free

On Tue, 16 Dec 2014 08:53:08 -0600 (CST)
Christoph Lameter <cl@...ux.com> wrote:

> On Tue, 16 Dec 2014, Joonsoo Kim wrote:
> 
> > > Like this:
> > >
> > >         return d > 0 && d < page->objects * s->size;
> > >
> >
> > Yes! That's what I'm looking for.
> > Christoph, how about above change?
> 
> Ok but now there is a multiplication in the fast path.

Could we pre-calculate the value (page->objects * s->size) and e.g store it
in struct kmem_cache, thus saving the imul ?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer
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