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From: Michel Lespinasse <walken@google.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Johannes Weiner <jweiner@redhat.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Hugh Dickins <hughd@google.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Michael Wolf <mjwolf@us.ibm.com>
Subject: Re: [PATCH 0/8] idle page tracking / working set estimation
Date: Tue, 27 Sep 2011 03:14:09 -0700	[thread overview]
Message-ID: <CANN689G4Z21v6fcF1dt-10CpQp9V42_hGPcPP2d5FChfCon_9Q@mail.gmail.com> (raw)
In-Reply-To: <CAKTCnzkzdQgut96NZf3Mi2kpOWW7N3qeybets5AHy7Gp8Wj_HQ@mail.gmail.com>

On Tue, Sep 27, 2011 at 3:03 AM, Balbir Singh <bsingharora@gmail.com> wrote:
> On Sat, Sep 17, 2011 at 9:09 AM, Michel Lespinasse <walken@google.com> wrote:
>> Patch 3 introduces page_referenced_kstaled(), which is similar to
>> page_referenced() but is used for idle page tracking rather than
>> for memory reclaimation. Since both functions clear the pte_young bits
>> and we don't want them to interfere with each other, two new page flags
>> are introduced that track when young pte references have been cleared by
>> each of the page_referenced variants.
>
> Sorry, I have trouble parsing this sentence, could you elaborate on "when"?

page_referenced() indicates if a page was accessed since the previous
page_referenced() call.

page_referenced_kstaled() indicates if a page was accessed since the
previous page_referenced_kstaled() call.

Both of the functions need to clear PTE young bits; however we don't
want the two functions to interfere with each other. To achieve this,
we add two page bits to indicate when a young PTE has been observed by
one of the functions but not by the other.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

WARNING: multiple messages have this Message-ID (diff)
From: Michel Lespinasse <walken@google.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Johannes Weiner <jweiner@redhat.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Hugh Dickins <hughd@google.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Michael Wolf <mjwolf@us.ibm.com>
Subject: Re: [PATCH 0/8] idle page tracking / working set estimation
Date: Tue, 27 Sep 2011 03:14:09 -0700	[thread overview]
Message-ID: <CANN689G4Z21v6fcF1dt-10CpQp9V42_hGPcPP2d5FChfCon_9Q@mail.gmail.com> (raw)
In-Reply-To: <CAKTCnzkzdQgut96NZf3Mi2kpOWW7N3qeybets5AHy7Gp8Wj_HQ@mail.gmail.com>

On Tue, Sep 27, 2011 at 3:03 AM, Balbir Singh <bsingharora@gmail.com> wrote:
> On Sat, Sep 17, 2011 at 9:09 AM, Michel Lespinasse <walken@google.com> wrote:
>> Patch 3 introduces page_referenced_kstaled(), which is similar to
>> page_referenced() but is used for idle page tracking rather than
>> for memory reclaimation. Since both functions clear the pte_young bits
>> and we don't want them to interfere with each other, two new page flags
>> are introduced that track when young pte references have been cleared by
>> each of the page_referenced variants.
>
> Sorry, I have trouble parsing this sentence, could you elaborate on "when"?

page_referenced() indicates if a page was accessed since the previous
page_referenced() call.

page_referenced_kstaled() indicates if a page was accessed since the
previous page_referenced_kstaled() call.

Both of the functions need to clear PTE young bits; however we don't
want the two functions to interfere with each other. To achieve this,
we add two page bits to indicate when a young PTE has been observed by
one of the functions but not by the other.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

--
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  reply	other threads:[~2011-09-27 10:14 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-17  3:39 [PATCH 0/8] idle page tracking / working set estimation Michel Lespinasse
2011-09-17  3:39 ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 1/8] page_referenced: replace vm_flags parameter with struct pr_info Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-17  3:44   ` Joe Perches
2011-09-17  3:44     ` Joe Perches
2011-09-17  4:51     ` Michel Lespinasse
2011-09-17  4:51       ` Michel Lespinasse
2011-09-20 19:05   ` Rik van Riel
2011-09-20 19:05     ` Rik van Riel
2011-09-21  2:51     ` Michel Lespinasse
2011-09-21  2:51       ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 2/8] kstaled: documentation and config option Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-20 21:23   ` Rik van Riel
2011-09-20 21:23     ` Rik van Riel
2011-09-23 19:27   ` Rik van Riel
2011-09-23 19:27     ` Rik van Riel
2011-09-17  3:39 ` [PATCH 3/8] kstaled: page_referenced_kstaled() and supporting infrastructure Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-20 19:36   ` Peter Zijlstra
2011-09-20 19:36     ` Peter Zijlstra
2011-09-17  3:39 ` [PATCH 4/8] kstaled: minimalistic implementation Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-22 23:14   ` Andrew Morton
2011-09-22 23:14     ` Andrew Morton
2011-09-23  8:37     ` Michel Lespinasse
2011-09-23  8:37       ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 5/8] kstaled: skip non-RAM regions Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 6/8] kstaled: rate limit pages scanned per second Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-22 23:15   ` Andrew Morton
2011-09-22 23:15     ` Andrew Morton
2011-09-23 10:18     ` Michel Lespinasse
2011-09-23 10:18       ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 7/8] kstaled: add histogram sampling functionality Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-22 23:15   ` Andrew Morton
2011-09-22 23:15     ` Andrew Morton
2011-09-23 10:26     ` Michel Lespinasse
2011-09-23 10:26       ` Michel Lespinasse
2011-09-17  3:39 ` [PATCH 8/8] kstaled: add incrementally updating stale page count Michel Lespinasse
2011-09-17  3:39   ` Michel Lespinasse
2011-09-22 23:13 ` [PATCH 0/8] idle page tracking / working set estimation Andrew Morton
2011-09-22 23:13   ` Andrew Morton
2011-09-23  1:23   ` Michel Lespinasse
2011-09-23  1:23     ` Michel Lespinasse
2011-09-27 10:03 ` Balbir Singh
2011-09-27 10:03   ` Balbir Singh
2011-09-27 10:14   ` Michel Lespinasse [this message]
2011-09-27 10:14     ` Michel Lespinasse
2011-09-27 16:50     ` Balbir Singh
2011-09-27 16:50       ` Balbir Singh

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