From: David Rientjes via Linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
davej@codemonkey.org.uk, x86@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
davem@davemloft.net
Subject: (unknown)
Date: Wed, 3 Feb 2016 08:52:46 +1100 (AEDT) [thread overview]
Message-ID: <mailman.1145.1454449904.12304.linuxppc-dev@lists.ozlabs.org> (raw)
In-Reply-To: <alpine.DEB.2.10.1601281500160.31035@chino.kir.corp.google.com>
[-- Attachment #1: Type: message/rfc822, Size: 5486 bytes --]
From: David Rientjes <rientjes@google.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net, Joonsoo Kim <iamjoonsoo.kim@lge.com>, davej@codemonkey.org.uk
Subject: Re: [PATCH v3 2/3] x86: query dynamic DEBUG_PAGEALLOC setting
Date: Tue, 2 Feb 2016 13:51:34 -0800 (PST)
Message-ID: <alpine.DEB.2.10.1602021351290.4977@chino.kir.corp.google.com>
On Thu, 28 Jan 2016, David Rientjes wrote:
> On Thu, 28 Jan 2016, Christian Borntraeger wrote:
>
> > Indeed, I only touched the identity mapping and dump stack.
> > The question is do we really want to change free_init_pages as well?
> > The unmapping during runtime causes significant overhead, but the
> > unmapping after init imposes almost no runtime overhead. Of course,
> > things get fishy now as what is enabled and what not.
> >
> > Kconfig after my patch "mm/debug_pagealloc: Ask users for default setting of debug_pagealloc"
> > (in mm) now states
> > ----snip----
> > By default this option will have a small overhead, e.g. by not
> > allowing the kernel mapping to be backed by large pages on some
> > architectures. Even bigger overhead comes when the debugging is
> > enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
> > command line parameter.
> > ----snip----
> >
> > So I am tempted to NOT change free_init_pages, but the x86 maintainers
> > can certainly decide differently. Ingo, Thomas, H. Peter, please advise.
> >
>
> I'm sorry, but I thought the discussion of the previous version of the
> patchset led to deciding that all CONFIG_DEBUG_PAGEALLOC behavior would be
> controlled by being enabled on the commandline and checked with
> debug_pagealloc_enabled().
>
> I don't think we should have a CONFIG_DEBUG_PAGEALLOC that does some stuff
> and then a commandline parameter or CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT
> to enable more stuff. It should either be all enabled by the commandline
> (or config option) or split into a separate entity.
> CONFIG_DEBUG_PAGEALLOC_LIGHT and CONFIG_DEBUG_PAGEALLOC would be fine, but
> the current state is very confusing about what is being done and what
> isn't.
>
Ping?
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next prev parent reply other threads:[~2016-02-02 21:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-27 10:09 [PATCH v3 0/3] Optimize CONFIG_DEBUG_PAGEALLOC Christian Borntraeger
2016-01-27 10:09 ` [PATCH v3 1/3] mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC Christian Borntraeger
2016-01-27 10:10 ` [PATCH v3 2/3] x86: query dynamic DEBUG_PAGEALLOC setting Christian Borntraeger
2016-01-27 22:17 ` David Rientjes
2016-01-28 9:48 ` Christian Borntraeger
2016-01-28 23:03 ` David Rientjes
2016-02-02 21:51 ` David Rientjes
2016-02-02 21:53 ` Christian Borntraeger
2016-02-02 22:21 ` Andrew Morton
2016-02-02 22:37 ` Christian Borntraeger
2016-02-02 23:04 ` Andrew Morton
2016-02-03 0:13 ` Stephen Rothwell
2016-02-02 21:52 ` David Rientjes via Linuxppc-dev [this message]
2016-01-28 23:04 ` (unknown) David Rientjes via Linuxppc-dev
2016-01-27 22:18 ` (unknown) David Rientjes via Linuxppc-dev
2016-01-27 10:10 ` [PATCH v3 3/3] s390: query dynamic DEBUG_PAGEALLOC setting Christian Borntraeger
2016-01-27 22:18 ` David Rientjes
2016-01-27 22:22 ` (unknown) David Rientjes via Linuxppc-dev
-- strict thread matches above, loose matches on Subject: below --
2004-03-04 14:11 (unknown) Jonathon Elmore
2004-02-22 4:41 (unknown) bhihjm
2003-01-24 5:08 (unknown), Anoop J.
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