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Date: Tue, 16 Dec 2014 19:34:37 +0400
Message-ID: <CAPAsAGxE9kGdjKwU_9w=ZsC6gWq6fs-SKMrSX4mYhBAtdPZasQ@mail.gmail.com>
Subject: Re: [PATCH 3/7] slub: Do not use c->page on free
From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        akpm@linuxfoundation.org, rostedt@goodmis.org,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Pekka Enberg <penberg@kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org

2014-12-16 18:15 GMT+03:00 Jesper Dangaard Brouer <brouer@redhat.com>:
> On Tue, 16 Dec 2014 08:53:08 -0600 (CST)
> Christoph Lameter <cl@linux.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 ?
>

No, one kmem_cache could have several pages with different orders,
therefore different page->objects.

> --
> 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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