From: Andrea Arcangeli <aarcange@redhat.com>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Gleb Natapov <gleb@redhat.com>, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, Marcelo Tosatti <mtosatti@redhat.com>,
Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>,
Izik Eidus <ieidus@redhat.com>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Nick Piggin <npiggin@suse.de>, Mel Gorman <mel@csn.ul.ie>,
Andi Kleen <andi@firstfloor.org>,
Dave Hansen <dave@linux.vnet.ibm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Ingo Molnar <mingo@elte.hu>, Mike Travis <travis@sgi.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Chris Wright <chrisw@sous-sol.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 00 of 30] Transparent Hugepage support #3
Date: Tue, 26 Jan 2010 17:19:19 +0100 [thread overview]
Message-ID: <20100126161919.GP30452@random.random> (raw)
In-Reply-To: <alpine.DEB.2.00.1001260955130.23549@router.home>
On Tue, Jan 26, 2010 at 09:55:43AM -0600, Christoph Lameter wrote:
> How does it do that? Take a reference on each of the 512 pieces? Or does
> it take one reference?
_zero_ reference! gup_fast is there only to pagein, in fact we need to
add one new type of gup_fast that won't take a reference at all and
only ensures the pmd_trans_huge pmd or the regular pte is mapped
before returning (or it will page it in before returning if it
wasn't), with mmu notifier it is always wasteful to take page
pins.
So for now you will run put_page immediately after gup_fast
returns. The whole point of mmu notifier is not to require any
refcount on the pages (or if there are, they are forced to be released
by the mmu notifier methods before they return, otherwise they defeat
the whole purpose of registering into mmu notifier). So the best is
not to take refcounts at all.
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next prev parent reply other threads:[~2010-01-26 16:21 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-21 6:20 [PATCH 00 of 30] Transparent Hugepage support #3 Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 01 of 30] define MADV_HUGEPAGE Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 02 of 30] compound_lock Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 03 of 30] alter compound get_page/put_page Andrea Arcangeli
2010-01-21 17:35 ` Dave Hansen
2010-01-23 17:39 ` Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 04 of 30] clear compound mapping Andrea Arcangeli
2010-01-21 17:43 ` Dave Hansen
2010-01-23 17:55 ` Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 05 of 30] add native_set_pmd_at Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 06 of 30] add pmd paravirt ops Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 07 of 30] no paravirt version of pmd ops Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 08 of 30] export maybe_mkwrite Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 09 of 30] comment reminder in destroy_compound_page Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 10 of 30] config_transparent_hugepage Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 11 of 30] add pmd mangling functions to x86 Andrea Arcangeli
2010-01-21 17:47 ` Dave Hansen
2010-01-21 19:14 ` Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 12 of 30] add pmd mangling generic functions Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 13 of 30] special pmd_trans_* functions Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 14 of 30] bail out gup_fast on splitting pmd Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 15 of 30] pte alloc trans splitting Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 16 of 30] add pmd mmu_notifier helpers Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 17 of 30] clear page compound Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 18 of 30] add pmd_huge_pte to mm_struct Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 19 of 30] ensure mapcount is taken on head pages Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 20 of 30] split_huge_page_mm/vma Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 21 of 30] split_huge_page paging Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 22 of 30] pmd_trans_huge migrate bugcheck Andrea Arcangeli
2010-01-21 20:40 ` Christoph Lameter
2010-01-21 23:01 ` Andrea Arcangeli
2010-01-21 23:17 ` Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 23 of 30] clear_copy_huge_page Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 24 of 30] kvm mmu transparent hugepage support Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 25 of 30] transparent hugepage core Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 26 of 30] madvise(MADV_HUGEPAGE) Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 27 of 30] memcg compound Andrea Arcangeli
2010-01-21 7:07 ` KAMEZAWA Hiroyuki
2010-01-21 15:44 ` Andrea Arcangeli
2010-01-21 23:55 ` KAMEZAWA Hiroyuki
2010-01-21 6:20 ` [PATCH 28 of 30] memcg huge memory Andrea Arcangeli
2010-01-21 7:16 ` KAMEZAWA Hiroyuki
2010-01-21 16:08 ` Andrea Arcangeli
2010-01-22 0:13 ` KAMEZAWA Hiroyuki
2010-01-27 11:27 ` Balbir Singh
2010-01-28 0:50 ` Daisuke Nishimura
2010-01-28 11:39 ` Andrea Arcangeli
2010-01-28 12:23 ` Balbir Singh
2010-01-28 12:36 ` Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 29 of 30] transparent hugepage vmstat Andrea Arcangeli
2010-01-21 6:20 ` [PATCH 30 of 30] khugepaged Andrea Arcangeli
2010-01-22 14:46 ` [PATCH 00 of 30] Transparent Hugepage support #3 Christoph Lameter
2010-01-22 15:19 ` Andrea Arcangeli
2010-01-22 16:51 ` Christoph Lameter
2010-01-23 17:58 ` Andrea Arcangeli
2010-01-25 21:50 ` Christoph Lameter
2010-01-25 22:46 ` Andrea Arcangeli
2010-01-26 15:47 ` Christoph Lameter
2010-01-26 16:11 ` Andrea Arcangeli
2010-01-26 16:30 ` Christoph Lameter
2010-01-26 16:45 ` Andrea Arcangeli
2010-01-26 18:23 ` Christoph Lameter
2010-01-26 17:09 ` Avi Kivity
2010-01-26 0:52 ` Rik van Riel
2010-01-26 6:53 ` Gleb Natapov
2010-01-26 12:35 ` Andrea Arcangeli
2010-01-26 15:55 ` Christoph Lameter
2010-01-26 16:19 ` Andrea Arcangeli [this message]
2010-01-26 15:54 ` Christoph Lameter
2010-01-26 16:16 ` Andrea Arcangeli
2010-01-26 16:24 ` Andi Kleen
2010-01-26 16:37 ` Christoph Lameter
2010-01-26 16:42 ` Mel Gorman
2010-01-26 16:52 ` Andrea Arcangeli
2010-01-26 17:26 ` Mel Gorman
2010-01-26 19:46 ` Andrea Arcangeli
2010-01-26 23:07 ` Rik van Riel
2010-01-27 18:33 ` Christoph Lameter
2010-01-26 11:24 ` Mel Gorman
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