From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Christoph Lameter <cl@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
tglx@linutronix.de, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: Allow migration of mlocked page?
Date: Tue, 15 May 2012 00:33:27 -0400 [thread overview]
Message-ID: <CAHGf_=qW6759UUxPvzoLfTdPCOHAahxN9DsPkkXHgoij9e5urg@mail.gmail.com> (raw)
In-Reply-To: <4FB1BC3E.3070107@kernel.org>
> Okay. Let's summary opinions in this thread until now.
>
> 1. mlock doesn't have pinning's semantic by definition of opengroup.
> 2. man page says "No page fault". It's bad. Maybe need fix up of man page.
Yes, it should be.
> 3. Thera are several places which already have migrate mlocked pages but it's okay because
> it's done under user's control while compaction/khugepagd doesn't.
I disagree. CPUSETS are used from admins. realtime _application_ is written
by application developers. ok, they are often overwrapped or the same. but it's
not exactly true. memory hotplug has similar situation.
Moreover, Think mix up rt-app and non-rt-migrate_pages-user-app situation. RT
app still be faced minor page fault and it's not expected from rt-app
developers.
> 3. Many application already used mlock by semantic of 2. So let's break legacy application if possible.
Many? really? I guess it's a very few.
> 4. CMA consider getting of free contiguos memory as top priority so latency may be okay in CMA
> while THP consider latency as top priority.
> 5. Let's define new API which would be
> 5.1 mlock(SOFT) - it can gaurantee memory-resident.
> 5.2 mlock(HARD) - it can gaurantee 1 and pinning.
> Current mlock could be 5.1, then we should implement 5.2. Or
> Current mlock could be 5.2, then we should implement 5.1
> We can implement it by PG_pinned or vma flags.
I definitely agree we need both pinned and not-pinned mlock.
> One of clear point is that it's okay to migrate mlocked page in CMA.
> And we can migrate mlocked anonymous pages and mlocked file pages by MIGRATE_ASYNC mode in compaction
> if we all agree Peter who says "mlocked mean NO MAJOR FAULT".
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next prev parent reply other threads:[~2012-05-15 4:33 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-11 4:37 Minchan Kim
2012-05-11 9:20 ` Peter Zijlstra
2012-05-11 16:20 ` Christoph Lameter
2012-05-11 23:24 ` KOSAKI Motohiro
2012-05-14 13:45 ` Christoph Lameter
2012-05-14 4:13 ` Minchan Kim
2012-05-14 6:56 ` Peter Zijlstra
2012-05-14 7:37 ` Minchan Kim
2012-05-14 7:45 ` Peter Zijlstra
2012-05-14 7:49 ` Peter Zijlstra
2012-05-14 7:54 ` Minchan Kim
2012-05-14 13:47 ` Christoph Lameter
2012-05-15 1:23 ` Minchan Kim
2012-05-15 11:07 ` Peter Zijlstra
2012-05-11 13:14 ` Mel Gorman
2012-05-11 23:25 ` KOSAKI Motohiro
2012-05-14 13:32 ` Mel Gorman
2012-05-14 13:51 ` Peter Zijlstra
2012-05-14 14:01 ` Christoph Lameter
2012-05-14 14:14 ` Peter Zijlstra
2012-05-14 14:43 ` Christoph Lameter
2012-05-14 22:52 ` KOSAKI Motohiro
2012-05-14 23:04 ` Roland Dreier
2012-05-15 14:27 ` Christoph Lameter
2012-05-15 1:38 ` Minchan Kim
2012-05-14 14:08 ` Peter Zijlstra
2012-05-14 23:06 ` KOSAKI Motohiro
2012-05-15 1:35 ` Minchan Kim
2012-05-14 4:25 ` Minchan Kim
2012-05-14 13:39 ` Mel Gorman
2012-05-15 2:15 ` Minchan Kim
2012-05-15 4:33 ` KOSAKI Motohiro [this message]
2012-05-15 11:06 ` Peter Zijlstra
2012-05-15 14:12 ` Christoph Lameter
2012-05-15 14:45 ` Peter Zijlstra
2012-05-15 15:11 ` Christoph Lameter
2012-05-15 14:10 ` Christoph Lameter
2012-05-15 14:09 ` Christoph Lameter
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