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Message-ID: <5a01986b-e412-44df-b376-fce7f8937b93@email.android.com>
Date: Thu, 29 Nov 2012 19:28:12 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: "Luck, Tony" <tony.luck@...el.com>, Mel Gorman <mgorman@...e.de>
CC: Jiang Liu <jiang.liu@...wei.com>,
Tang Chen <tangchen@...fujitsu.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"rob@...dley.net" <rob@...dley.net>,
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Len Brown <lenb@...nel.org>,
"Wang, Frank" <frank.wang@...el.com>
Subject: RE: [PATCH v2 0/5] Add movablecore_map boot option
Disk I/O is still a big consumer of lowmem.
"Luck, Tony" <tony.luck@...el.com> wrote:
>> If any significant percentage of memory is in ZONE_MOVABLE then the
>memory
>> hotplug people will have to deal with all the lowmem/highmem problems
>> that used to be faced by 32-bit x86 with PAE enabled.
>
>While these problems may still exist on large systems - I think it
>becomes
>harder to construct workloads that run into problems. In those bad old
>days
>a significant fraction of lowmem was consumed by the kernel ... so it
>was
>pretty easy to find meta-data intensive workloads that would push it
>over
>a cliff. Here we are talking about systems with say 128GB per node
>divided
>into 64GB moveable and 64GB non-moveable (and I'd regard this as a
>rather
>low-end machine). Unless the workload consists of zillions of tiny
>processes
>all mapping shared memory blocks, the percentage of memory allocated to
>the kernel is going to be tiny compared with the old 4GB days.
>
>-Tony
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
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