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From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Linux-MM <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	Xishi Qiu <qiuxishi@huawei.com>,
	Kani Toshimitsu <toshi.kani@hpe.com>,
	slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove zone restrictions
Date: Thu, 6 Jul 2017 08:56:50 +0200	[thread overview]
Message-ID: <20170706065649.GC29724@dhcp22.suse.cz> (raw)
In-Reply-To: <20170705231649.GA10155@WeideMacBook-Pro.local>

On Thu 06-07-17 07:16:49, Wei Yang wrote:
> On Fri, Jun 30, 2017 at 01:01:18PM +0200, Michal Hocko wrote:
> >On Fri 30-06-17 11:55:45, Michal Hocko wrote:
> >> On Fri 30-06-17 17:39:56, Wei Yang wrote:
> >> > On Fri, Jun 30, 2017 at 4:39 PM, Michal Hocko <mhocko@kernel.org> wrote:
> >> [...]
> >> > > yes and to be honest I do not plan to fix it unless somebody has a real
> >> > > life usecase for it. Now that we allow explicit onlininig type anywhere
> >> > > it seems like a reasonable behavior and this will allow us to remove
> >> > > quite some code which is always a good deal wrt longterm maintenance.
> >> > >
> >> > 
> >> > hmm... the statistics displayed in /proc/zoneinfo would be meaningless
> >> > for zone_normal and zone_movable.
> >> 
> >> Why would they be meaningless? Counters will always reflect the actual
> >> use - if not then it is a bug. And wrt to zone description what is
> >> meaningless about
> >> memory34/valid_zones:Normal
> >> memory35/valid_zones:Normal Movable
> >> memory36/valid_zones:Movable
> >> memory37/valid_zones:Movable Normal
> >> memory38/valid_zones:Movable Normal
> >> memory39/valid_zones:Movable Normal
> >> memory40/valid_zones:Normal
> >> memory41/valid_zones:Movable
> >> 
> >> And
> >> Node 1, zone   Normal
> >>   pages free     65465
> >>         min      156
> >>         low      221
> >>         high     286
> >>         spanned  229376
> >>         present  65536
> >>         managed  65536
> >> [...]
> >>   start_pfn:           1114112
> >> Node 1, zone  Movable
> >>   pages free     65443
> >>         min      156
> >>         low      221
> >>         high     286
> >>         spanned  196608
> >>         present  65536
> >>         managed  65536
> >> [...]
> >>   start_pfn:           1179648
> >> 
> >> ranges are clearly defined as [start_pfn, start_pfn+managed] and managed
> >
> >errr, this should be [start_pfn, start_pfn + spanned] of course.
> >
> 
> The spanned is not adjusted after offline, neither does start_pfn. For example,
> even offline all the movable_zone range, we can still see the spanned.

Which is completely valid. Offline only changes present/managed.

> Below is a result with a little changed kernel to show the start_pfn always.
> The sequence is:
> 1. bootup
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  0
> 	managed  0
>   start_pfn:           0
> 
> 2. online movable 2 continuous memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  65536
> 	managed  65536
>   start_pfn:           1310720
> 
> 3. offline 2nd memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  32768
> 	managed  32768
>   start_pfn:           1310720
> 
> 4. offline 1st memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  0
> 	managed  0
>   start_pfn:           1310720
> 
> So I am not sure this is still clearly defined?

Could you be more specific what is not clearly defined? You have
offlined all online memory blocks so present/managed is 0 while the
spanned is unchanged because the zone is still defined in range
[1310720, 1376256].

I also do not see how this is related with the discussed patch as there
is no zone interleaving involved.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Linux-MM <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	Xishi Qiu <qiuxishi@huawei.com>,
	Kani Toshimitsu <toshi.kani@hpe.com>,
	slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove zone restrictions
Date: Thu, 6 Jul 2017 08:56:50 +0200	[thread overview]
Message-ID: <20170706065649.GC29724@dhcp22.suse.cz> (raw)
In-Reply-To: <20170705231649.GA10155@WeideMacBook-Pro.local>

On Thu 06-07-17 07:16:49, Wei Yang wrote:
> On Fri, Jun 30, 2017 at 01:01:18PM +0200, Michal Hocko wrote:
> >On Fri 30-06-17 11:55:45, Michal Hocko wrote:
> >> On Fri 30-06-17 17:39:56, Wei Yang wrote:
> >> > On Fri, Jun 30, 2017 at 4:39 PM, Michal Hocko <mhocko@kernel.org> wrote:
> >> [...]
> >> > > yes and to be honest I do not plan to fix it unless somebody has a real
> >> > > life usecase for it. Now that we allow explicit onlininig type anywhere
> >> > > it seems like a reasonable behavior and this will allow us to remove
> >> > > quite some code which is always a good deal wrt longterm maintenance.
> >> > >
> >> > 
> >> > hmm... the statistics displayed in /proc/zoneinfo would be meaningless
> >> > for zone_normal and zone_movable.
> >> 
> >> Why would they be meaningless? Counters will always reflect the actual
> >> use - if not then it is a bug. And wrt to zone description what is
> >> meaningless about
> >> memory34/valid_zones:Normal
> >> memory35/valid_zones:Normal Movable
> >> memory36/valid_zones:Movable
> >> memory37/valid_zones:Movable Normal
> >> memory38/valid_zones:Movable Normal
> >> memory39/valid_zones:Movable Normal
> >> memory40/valid_zones:Normal
> >> memory41/valid_zones:Movable
> >> 
> >> And
> >> Node 1, zone   Normal
> >>   pages free     65465
> >>         min      156
> >>         low      221
> >>         high     286
> >>         spanned  229376
> >>         present  65536
> >>         managed  65536
> >> [...]
> >>   start_pfn:           1114112
> >> Node 1, zone  Movable
> >>   pages free     65443
> >>         min      156
> >>         low      221
> >>         high     286
> >>         spanned  196608
> >>         present  65536
> >>         managed  65536
> >> [...]
> >>   start_pfn:           1179648
> >> 
> >> ranges are clearly defined as [start_pfn, start_pfn+managed] and managed
> >
> >errr, this should be [start_pfn, start_pfn + spanned] of course.
> >
> 
> The spanned is not adjusted after offline, neither does start_pfn. For example,
> even offline all the movable_zone range, we can still see the spanned.

Which is completely valid. Offline only changes present/managed.

> Below is a result with a little changed kernel to show the start_pfn always.
> The sequence is:
> 1. bootup
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  0
> 	managed  0
>   start_pfn:           0
> 
> 2. online movable 2 continuous memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  65536
> 	managed  65536
>   start_pfn:           1310720
> 
> 3. offline 2nd memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  32768
> 	managed  32768
>   start_pfn:           1310720
> 
> 4. offline 1st memory_blocks
> 
> Node 0, zone  Movable
>         spanned  65536
> 	present  0
> 	managed  0
>   start_pfn:           1310720
> 
> So I am not sure this is still clearly defined?

Could you be more specific what is not clearly defined? You have
offlined all online memory blocks so present/managed is 0 while the
spanned is unchanged because the zone is still defined in range
[1310720, 1376256].

I also do not see how this is related with the discussed patch as there
is no zone interleaving involved.
-- 
Michal Hocko
SUSE Labs

--
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  reply	other threads:[~2017-07-06  6:56 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-29  7:35 [RFC PATCH 0/2] mm, memory_hotplug: remove zone onlining restriction Michal Hocko
2017-06-29  7:35 ` Michal Hocko
2017-06-29  7:35 ` [PATCH 1/2] mm, memory_hotplug: display allowed zones in the preferred ordering Michal Hocko
2017-06-29  7:35   ` Michal Hocko
2017-06-30  0:45   ` Joonsoo Kim
2017-06-30  0:45     ` Joonsoo Kim
2017-07-07 14:34   ` Vlastimil Babka
2017-07-07 14:34     ` Vlastimil Babka
2017-06-29  7:35 ` [PATCH 2/2] mm, memory_hotplug: remove zone restrictions Michal Hocko
2017-06-29  7:35   ` Michal Hocko
2017-06-30  1:16   ` Joonsoo Kim
2017-06-30  1:16     ` Joonsoo Kim
2017-06-30  3:09   ` Wei Yang
2017-06-30  3:09     ` Wei Yang
2017-06-30  8:39     ` Michal Hocko
2017-06-30  8:39       ` Michal Hocko
2017-06-30  9:39       ` Wei Yang
2017-06-30  9:39         ` Wei Yang
2017-06-30  9:55         ` Michal Hocko
2017-06-30  9:55           ` Michal Hocko
2017-06-30 11:01           ` Michal Hocko
2017-06-30 11:01             ` Michal Hocko
2017-07-05 23:16             ` Wei Yang
2017-07-06  6:56               ` Michal Hocko [this message]
2017-07-06  6:56                 ` Michal Hocko
2017-07-07  8:37                 ` Wei Yang
2017-07-07 12:41                   ` Michal Hocko
2017-07-07 12:41                     ` Michal Hocko
2017-07-07 15:02   ` Vlastimil Babka
2017-07-07 15:02     ` Vlastimil Babka
2017-07-10  6:45     ` Michal Hocko
2017-07-10  6:45       ` Michal Hocko
2017-07-10 11:11       ` Vlastimil Babka
2017-07-10 11:11         ` Vlastimil Babka
2017-07-10 11:17         ` Michal Hocko
2017-07-10 11:17           ` Michal Hocko
2017-07-10 12:12           ` Vlastimil Babka
2017-07-10 12:12             ` Vlastimil Babka
2017-07-10 12:30             ` Michal Hocko
2017-07-10 12:30               ` Michal Hocko
2017-07-12 12:49   ` Michal Hocko
2017-07-12 12:49     ` Michal Hocko
2017-07-14 12:12 [PATCH 0/2] mm, memory_hotplug: remove zone onlining restriction Michal Hocko
2017-07-14 12:12 ` [PATCH 2/2] mm, memory_hotplug: remove zone restrictions Michal Hocko
2017-07-14 12:12   ` Michal Hocko
2017-07-14 12:17   ` Vlastimil Babka
2017-07-14 12:17     ` Vlastimil Babka
2017-07-14 14:26   ` Reza Arbab
2017-07-14 14:26     ` Reza Arbab

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