From: Lin Feng <linfeng@cn.fujitsu.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
bcrl@kvack.org, viro@zeniv.linux.org.uk, khlebnikov@openvz.org,
walken@google.com, kamezawa.hiroyu@jp.fujitsu.com,
minchan@kernel.org, riel@redhat.com, rientjes@google.com,
isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com,
laijs@cn.fujitsu.com, jiang.liu@huawei.com, linux-mm@kvack.org,
linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: hotplug: implement non-movable version of get_user_pages() called get_user_pages_non_movable()
Date: Tue, 19 Feb 2013 17:55:30 +0800 [thread overview]
Message-ID: <51234C12.4020404@cn.fujitsu.com> (raw)
In-Reply-To: <20130218151716.GL4365@suse.de>
Hi Mel,
On 02/18/2013 11:17 PM, Mel Gorman wrote:
>>> > > <SNIP>
>>> > >
>>> > > result. It's a little clumsy but the memory hot-remove failure message
>>> > > could list what applications have pinned the pages that cannot be removed
>>> > > so the administrator has the option of force-killing the application. It
>>> > > is possible to discover what application is pinning a page from userspace
>>> > > but it would involve an expensive search with /proc/kpagemap
>>> > >
>>>>> > >>> + if (migrate_pre_flag && !isolate_err) {
>>>>> > >>> + ret = migrate_pages(&pagelist, alloc_migrate_target, 1,
>>>>> > >>> + false, MIGRATE_SYNC, MR_SYSCALL);
>>> > >
>>> > > The conversion of alloc_migrate_target is a bit problematic. It strips
>>> > > the __GFP_MOVABLE flag and the consequence of this is that it converts
>>> > > those allocation requests to MIGRATE_UNMOVABLE. This potentially is a large
>>> > > number of pages, particularly if the number of get_user_pages_non_movable()
>>> > > increases for short-lived pins like direct IO.
>> >
>> > Sorry, I don't quite understand here neither. If we use the following new
>> > migration allocation function as you said, the increasing number of
>> > get_user_pages_non_movable() will also lead to large numbers of MIGRATE_UNMOVABLE
>> > pages. What's the difference, do I miss something?
>> >
> The replacement function preserves the __GFP_MOVABLE flag. It cannot use
> ZONE_MOVABLE but otherwise the newly allocated page will be grouped with
> other movable pages.
Ah, got it " But GFP_MOVABLE is not only a zone specifier but also an allocation policy.".
Could I clear __GFP_HIGHMEM flag in alloc_migrate_target depending on private parameter so
that we can keep MIGRATE_UNMOVABLE policy also allocate page none movable zones with little
change?
Does that approach work? Otherwise I have to follow your suggestion.
thanks,
linfeng
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next prev parent reply other threads:[~2013-02-19 9:55 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-04 10:04 [PATCH 0/2] mm: hotplug: implement non-movable version of get_user_pages() to kill long-time pin pages Lin Feng
2013-02-04 10:04 ` [PATCH 1/2] mm: hotplug: implement non-movable version of get_user_pages() called get_user_pages_non_movable() Lin Feng
2013-02-05 0:06 ` Andrew Morton
2013-02-05 0:18 ` Andrew Morton
2013-02-05 3:09 ` Lin Feng
2013-02-05 21:13 ` Andrew Morton
2013-02-05 11:57 ` Mel Gorman
2013-02-05 13:32 ` Mel Gorman
2013-02-19 13:37 ` Lin Feng
2013-02-20 2:34 ` Lin Feng
2013-02-20 2:44 ` Wanpeng Li
2013-02-20 2:44 ` Wanpeng Li
[not found] ` <20130220024435.GA30208@hacker.(null)>
2013-02-20 2:59 ` Lin Feng
2013-02-20 9:58 ` Simon Jeons
2013-02-20 10:23 ` Lin Feng
2013-02-20 11:31 ` Simon Jeons
2013-02-20 11:54 ` Lin Feng
2013-02-06 2:26 ` Michel Lespinasse
2013-02-06 10:41 ` Mel Gorman
2013-02-18 10:34 ` Lin Feng
2013-02-18 15:17 ` Mel Gorman
2013-02-19 9:55 ` Lin Feng [this message]
2013-02-19 10:34 ` Mel Gorman
2013-02-04 10:04 ` [PATCH 2/2] fs/aio.c: use get_user_pages_non_movable() to pin ring pages when support memory hotremove Lin Feng
2013-02-04 15:18 ` Jeff Moyer
2013-02-04 23:02 ` Zach Brown
2013-02-05 5:35 ` Lin Feng
2013-02-05 5:06 ` Lin Feng
2013-02-05 0:58 ` [PATCH 0/2] mm: hotplug: implement non-movable version of get_user_pages() to kill long-time pin pages Minchan Kim
2013-02-05 4:42 ` Lin Feng
2013-02-05 5:25 ` Minchan Kim
2013-02-05 6:18 ` Lin Feng
2013-02-05 7:45 ` Minchan Kim
2013-02-05 8:27 ` Lin Feng
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