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From: Johannes Weiner <hannes@cmpxchg.org>
To: Dave Hansen <dave@linux.vnet.ibm.com>
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 1/6] count transparent hugepage splits
Date: Tue, 1 Feb 2011 10:58:08 +0100	[thread overview]
Message-ID: <20110201095808.GG19534@cmpxchg.org> (raw)
In-Reply-To: <20110201003358.98826457@kernel>

On Mon, Jan 31, 2011 at 04:33:58PM -0800, Dave Hansen wrote:
> 
> The khugepaged process collapses transparent hugepages for us.  Whenever
> it collapses a page into a transparent hugepage, we increment a nice
> global counter exported in sysfs:
> 
> 	/sys/kernel/mm/transparent_hugepage/khugepaged/pages_collapsed
> 
> But, transparent hugepages also get broken down in quite a few
> places in the kernel.  We do not have a good idea how how many of
> those collpased pages are "new" versus how many are just fixing up
> spots that got split a moment before.
> 
> Note: "splits" and "collapses" are opposites in this context.
> 
> This patch adds a new sysfs file:
> 
> 	/sys/kernel/mm/transparent_hugepage/pages_split
> 
> It is global, like "pages_collapsed", and is incremented whenever any
> transparent hugepage on the system has been broken down in to normal
> PAGE_SIZE base pages.  This way, we can get an idea how well khugepaged
> is keeping up collapsing pages that have been split.
> 
> I put it under /sys/kernel/mm/transparent_hugepage/ instead of the
> khugepaged/ directory since it is not strictly related to
> khugepaged; it can get incremented on pages other than those
> collapsed by khugepaged.
> 
> The variable storing this is a plain integer.  I needs the same
> amount of locking that 'khugepaged_pages_collapsed' has, for
> instance.
> 
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

  reply	other threads:[~2011-02-01  9:58 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 [this message]
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
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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