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From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
	Christoph Lameter <cl@gentwo.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Steve Capper <steve.capper@linaro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>,
	Jerome Marchand <jmarchan@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 4/4] thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers
Date: Wed, 3 Feb 2016 14:43:16 -0800	[thread overview]
Message-ID: <20160203144316.f01573516f186071bb2cf1bf@linux-foundation.org> (raw)
In-Reply-To: <56B21FC9.9040009@intel.com>

On Wed, 3 Feb 2016 07:42:01 -0800 Dave Hansen <dave.hansen@intel.com> wrote:

> On 02/03/2016 07:14 AM, Kirill A. Shutemov wrote:
> > But the new variant is somewhat slower. Current helpers iterates over
> > VMAs the compound page is mapped to, and then over ptes within this VMA.
> > New helpers iterates over small page, then over VMA the small page
> > mapped to, and only then find relevant pte.
> 
> The code simplification here is really attractive.  Can you quantify
> what the slowdown is?  Is it noticeable, or would it be in the noise
> during all the other stuff that happens under memory pressure?

yup.  And the "more testing is required" is a bit worrisome.  Is this
code really ready for getting pounded upon in -next?

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
	Christoph Lameter <cl@gentwo.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Steve Capper <steve.capper@linaro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>,
	Jerome Marchand <jmarchan@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 4/4] thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers
Date: Wed, 3 Feb 2016 14:43:16 -0800	[thread overview]
Message-ID: <20160203144316.f01573516f186071bb2cf1bf@linux-foundation.org> (raw)
In-Reply-To: <56B21FC9.9040009@intel.com>

On Wed, 3 Feb 2016 07:42:01 -0800 Dave Hansen <dave.hansen@intel.com> wrote:

> On 02/03/2016 07:14 AM, Kirill A. Shutemov wrote:
> > But the new variant is somewhat slower. Current helpers iterates over
> > VMAs the compound page is mapped to, and then over ptes within this VMA.
> > New helpers iterates over small page, then over VMA the small page
> > mapped to, and only then find relevant pte.
> 
> The code simplification here is really attractive.  Can you quantify
> what the slowdown is?  Is it noticeable, or would it be in the noise
> during all the other stuff that happens under memory pressure?

yup.  And the "more testing is required" is a bit worrisome.  Is this
code really ready for getting pounded upon in -next?

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  reply	other threads:[~2016-02-03 22:43 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 15:14 [PATCH 0/4] thp: simplify freeze_page() and unfreeze_page() Kirill A. Shutemov
2016-02-03 15:14 ` Kirill A. Shutemov
2016-02-03 15:14 ` [PATCH 1/4] rmap: introduce rmap_walk_locked() Kirill A. Shutemov
2016-02-03 15:14   ` Kirill A. Shutemov
2016-02-03 22:40   ` Andrew Morton
2016-02-03 22:40     ` Andrew Morton
2016-02-03 22:45     ` Kirill A. Shutemov
2016-02-03 22:45       ` Kirill A. Shutemov
2016-02-03 22:56       ` Andrew Morton
2016-02-03 22:56         ` Andrew Morton
2016-02-04 14:37         ` Kirill A. Shutemov
2016-02-04 14:37           ` Kirill A. Shutemov
2016-02-03 15:14 ` [PATCH 2/4] rmap: extend try_to_unmap() to be usable by split_huge_page() Kirill A. Shutemov
2016-02-03 15:14   ` Kirill A. Shutemov
2016-02-03 15:14 ` [PATCH 3/4] mm: make remove_migration_ptes() beyond mm/migration.c Kirill A. Shutemov
2016-02-03 15:14   ` Kirill A. Shutemov
2016-02-03 15:14 ` [PATCH 4/4] thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers Kirill A. Shutemov
2016-02-03 15:14   ` Kirill A. Shutemov
2016-02-03 15:42   ` Dave Hansen
2016-02-03 15:42     ` Dave Hansen
2016-02-03 22:43     ` Andrew Morton [this message]
2016-02-03 22:43       ` Andrew Morton
2016-02-03 22:53       ` Kirill A. Shutemov
2016-02-03 22:53         ` Kirill A. Shutemov
2016-02-04 14:27     ` Kirill A. Shutemov
2016-02-04 14:27       ` Kirill A. Shutemov
2016-02-04 23:58     ` Kirill A. Shutemov
2016-02-04 23:58       ` Kirill A. Shutemov

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