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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@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: Thu, 4 Feb 2016 01:53:04 +0300	[thread overview]
Message-ID: <20160203225304.GB22605@black.fi.intel.com> (raw)
In-Reply-To: <20160203144316.f01573516f186071bb2cf1bf@linux-foundation.org>

On Wed, Feb 03, 2016 at 02:43:16PM -0800, Andrew Morton wrote:
> 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.

It is not really clear, how to quantify this properly. Let me think more
about it.

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

By now it survived 5+ hours of fuzzing in 16 VM in parallel. I'll continue
with other tests tomorrow.

-- 
 Kirill A. Shutemov

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  reply	other threads:[~2016-02-03 22:53 UTC|newest]

Thread overview: 14+ 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 ` [PATCH 1/4] rmap: introduce rmap_walk_locked() Kirill A. Shutemov
2016-02-03 22:40   ` Andrew Morton
2016-02-03 22:45     ` Kirill A. Shutemov
2016-02-03 22:56       ` Andrew Morton
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 ` [PATCH 3/4] mm: make remove_migration_ptes() beyond mm/migration.c 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 15:42   ` Dave Hansen
2016-02-03 22:43     ` Andrew Morton
2016-02-03 22:53       ` Kirill A. Shutemov [this message]
2016-02-04 14:27     ` Kirill A. Shutemov
2016-02-04 23:58     ` Kirill A. Shutemov

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