RE: [PATCH v2 0/5] Add movablecore_map boot option

[H. Peter Anvin]

Disk I/O is still a big consumer of lowmem.

"Luck, Tony" <tony.luck@xxxxxxxxx> 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

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