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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Michael J Wolf <mjwolf@us.ibm.com>,
	Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [RFC][PATCH 2/6] pagewalk: only split huge pages when necessary
Date: Tue, 01 Feb 2011 07:03:56 -0800	[thread overview]
Message-ID: <1296572636.27022.2870.camel@nimitz> (raw)
In-Reply-To: <20110201100433.GH19534@cmpxchg.org>

On Tue, 2011-02-01 at 11:04 +0100, Johannes Weiner wrote:
> On Mon, Jan 31, 2011 at 04:33:59PM -0800, Dave Hansen wrote:
> > Right now, if a mm_walk has either ->pte_entry or ->pmd_entry
> > set, it will unconditionally split and transparent huge pages
> > it runs in to.  In practice, that means that anyone doing a
> > 
> >       cat /proc/$pid/smaps
> > 
> > will unconditionally break down every huge page in the process
> > and depend on khugepaged to re-collapse it later.  This is
> > fairly suboptimal.
> > 
> > This patch changes that behavior.  It teaches each ->pmd_entry
> > handler (there are three) that they must break down the THPs
> > themselves.  Also, the _generic_ code will never break down
> > a THP unless a ->pte_entry handler is actually set.
> > 
> > This means that the ->pmd_entry handlers can now choose to
> > deal with THPs without breaking them down.
> 
> Makes perfect sense.  But you forgot to push down the splitting into
> the two handlers in mm/memcontrol.c. 

I did indeed.  I'll go fix those up.  Thanks for the review!

-- Dave


  reply	other threads:[~2011-02-01 15:04 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-01  0:33 [RFC][PATCH 0/6] more detailed per-process transparent hugepage statistics Dave Hansen
2011-02-01  0:33 ` [RFC][PATCH 1/6] count transparent hugepage splits Dave Hansen
2011-02-01  9:58   ` Johannes Weiner
2011-02-03 21:22   ` David Rientjes
2011-02-04 21:18     ` Andrea Arcangeli
2011-02-04 21:28       ` Dave Hansen
2011-02-01  0:33 ` [RFC][PATCH 2/6] pagewalk: only split huge pages when necessary Dave Hansen
2011-02-01 10:04   ` Johannes Weiner
2011-02-01 15:03     ` Dave Hansen [this message]
2011-02-03 21:22   ` David Rientjes
2011-02-03 21:33     ` Dave Hansen
2011-02-03 21:46       ` David Rientjes
2011-02-04 17:19         ` Dave Hansen
2011-02-04 21:10           ` Andrea Arcangeli
2011-02-01  0:34 ` [RFC][PATCH 3/6] break out smaps_pte_entry() from smaps_pte_range() Dave Hansen
2011-02-01 10:08   ` Johannes Weiner
2011-02-03 21:22   ` David Rientjes
2011-02-03 21:40     ` Dave Hansen
2011-02-01  0:34 ` [RFC][PATCH 4/6] pass pte size argument in to smaps_pte_entry() Dave Hansen
2011-02-01 10:09   ` Johannes Weiner
2011-02-03 21:22   ` David Rientjes
2011-02-01  0:34 ` [RFC][PATCH 5/6] teach smaps_pte_range() about THP pmds Dave Hansen
2011-02-01 10:11   ` Johannes Weiner
2011-02-01 15:02     ` Dave Hansen
2011-02-01 16:09       ` Andrea Arcangeli
2011-02-03 21:22   ` David Rientjes
2011-02-03 21:34     ` Dave Hansen
2011-02-01  0:34 ` [RFC][PATCH 6/6] have smaps show transparent huge pages Dave Hansen
2011-02-01 10:12   ` Johannes Weiner
2011-02-03 21:22   ` David Rientjes
2011-02-01 15:38 ` [RFC][PATCH 0/6] more detailed per-process transparent hugepage statistics Andrea Arcangeli
2011-02-01 17:15   ` Dave Hansen
2011-02-01 20:39     ` Andrea Arcangeli
2011-02-01 20:56       ` Dave Hansen
2011-02-02  0:07         ` Andrea Arcangeli
2011-02-08 17:54           ` Dave Hansen
2011-02-08 18:17             ` Andrea Arcangeli
2011-02-03 21:54 ` David Rientjes

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