From: Michal Hocko <mhocko@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@suse.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-doc@vger.kernel.org
Subject: Re: [patch 1/2] mm, page_alloc: extend kernelcore and movablecore for percent
Date: Thu, 15 Feb 2018 15:45:25 +0100 [thread overview]
Message-ID: <20180215144525.GG7275@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.10.1802140225290.261065@chino.kir.corp.google.com>
On Wed 14-02-18 02:28:38, David Rientjes wrote:
> On Wed, 14 Feb 2018, Michal Hocko wrote:
>
> > I do not have any objections regarding the extension. What I am more
> > interested in is _why_ people are still using this command line
> > parameter at all these days. Why would anybody want to introduce lowmem
> > issues from 32b days. I can see the CMA/Hotplug usecases for
> > ZONE_MOVABLE but those have their own ways to define zone movable. I was
> > tempted to simply remove the kernelcore already. Could you be more
> > specific what is your usecase which triggered a need of an easier
> > scaling of the size?
>
> Fragmentation of non-__GFP_MOVABLE pages due to low on memory situations
> can pollute most pageblocks on the system, as much as 1GB of slab being
> fragmented over 128GB of memory, for example.
OK, I was assuming something like that.
> When the amount of kernel
> memory is well bounded for certain systems, it is better to aggressively
> reclaim from existing MIGRATE_UNMOVABLE pageblocks rather than eagerly
> fallback to others.
>
> We have additional patches that help with this fragmentation if you're
> interested, specifically kcompactd compaction of MIGRATE_UNMOVABLE
> pageblocks triggered by fallback of non-__GFP_MOVABLE allocations and
> draining of pcp lists back to the zone free area to prevent stranding.
Yes, I think we need a proper fix. (Ab)using zone_movable for this
usecase is just sad.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2018-02-15 14:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-13 0:24 David Rientjes
2018-02-13 0:24 ` [patch 2/2] mm, page_alloc: move mirrored_kernelcore to __meminitdata David Rientjes
2018-02-13 23:46 ` [patch 1/2] mm, page_alloc: extend kernelcore and movablecore for percent Andrew Morton
2018-02-13 23:55 ` David Rientjes
2018-02-14 1:14 ` Andrew Morton
2018-02-14 0:37 ` Mike Kravetz
2018-02-14 0:53 ` David Rientjes
2018-02-14 1:00 ` [patch -mm] mm, page_alloc: extend kernelcore and movablecore for percent fix David Rientjes
2018-02-14 1:10 ` Mike Kravetz
2018-02-14 9:59 ` [patch 1/2] mm, page_alloc: extend kernelcore and movablecore for percent Michal Hocko
2018-02-14 10:28 ` David Rientjes
2018-02-15 14:45 ` Michal Hocko [this message]
2018-02-15 15:11 ` Matthew Wilcox
2018-02-15 15:49 ` Christopher Lameter
2018-02-15 20:14 ` Matthew Wilcox
2018-02-16 15:41 ` Christopher Lameter
2018-02-15 20:48 ` Matthew Wilcox
2018-02-16 0:45 ` David Rientjes
2018-02-16 15:44 ` Christopher Lameter
2018-02-16 16:01 ` Matthew Wilcox
2018-02-16 16:08 ` Christopher Lameter
2018-02-16 17:09 ` Matthew Wilcox
2018-02-15 20:47 ` David Rientjes
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