From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <benh@kernel.crashing.org>
Received: from gate.crashing.org (gate.crashing.org [63.228.1.57])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (Client did not present a certificate)
 by ozlabs.org (Postfix) with ESMTPS id 680A02C007E
 for <linuxppc-dev@lists.ozlabs.org>; Mon,  9 Dec 2013 17:19:56 +1100 (EST)
Message-ID: <1386569986.5159.41.camel@pasglop>
Subject: Re: [PATCH 1/3] powerpc: mm: make _PAGE_NUMA take effect
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Liu ping fan <kernelfans@gmail.com>
Date: Mon, 09 Dec 2013 17:19:46 +1100
In-Reply-To: <CAFgQCTtJh1-2wuLueREbA6ru5cje4EcxN5yT+cU-YNSrZi9O=Q@mail.gmail.com>
References: <1386140348-7854-1-git-send-email-pingfank@linux.vnet.ibm.com>
 <1386140348-7854-2-git-send-email-pingfank@linux.vnet.ibm.com>
 <87a9gfva9n.fsf@linux.vnet.ibm.com> <1386549112.5159.4.camel@pasglop>
 <CAFgQCTtJh1-2wuLueREbA6ru5cje4EcxN5yT+cU-YNSrZi9O=Q@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Cc: Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org,
 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>

On Mon, 2013-12-09 at 14:17 +0800, Liu ping fan wrote:
> On Mon, Dec 9, 2013 at 8:31 AM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > On Thu, 2013-12-05 at 16:23 +0530, Aneesh Kumar K.V wrote:
> >> Liu Ping Fan <kernelfans@gmail.com> writes:
> >>
> >> > To enable the do_numa_page(), we should not fix _PAGE_NUMA in
> >> > hash_page(), so bail out for the case of pte_numa().
> >
> > For some reason I don't have 2/3 and 3/3 in my mbox (though I do have
> > them on patchwork) so I'll reply to this one.
> >
> > Overall, your statement that this is a faster path needs to be backed up
> > with numbers.
> >
> > The code is complicated enough as it-is, such additional mess in the low
> > level hashing code requires a good justification, and also a
> > demonstration that it doesn't add overhead to the normal hash path.
> >
> For the test, is it ok to have an user application to copy page where
> all page are PG_mlocked?

If that specific scenario is relevant in practice, then yes, though also
demonstrate the lack of regression with some more normal path such as a
kernel compile.

Cheers,
Ben.