Thread (47 messages) 47 messages, 6 authors, 2013-02-07

Re: [PATCH v5 01/14] memory-hotplug: try to offline the memory twice to avoid dependence

From: Tang Chen <hidden>
Date: 2013-02-07 07:57:32
Also in: linux-acpi, linux-mm, linux-s390, linuxppc-dev, lkml, sparclinux

On 02/06/2013 10:24 PM, Glauber Costa wrote:
quoted
quoted
quoted
And one more question, a memory section is 128MB in Linux. If we reserve
part of the them for page_cgroup,
then anyone who wants to allocate a contiguous memory larger than 128MB,
it will fail, right ?
Is it OK ?
No, it is not.

Another take on this: Can't we free all the page_cgroup structure before
we actually start removing the sections ? If we do this, we would be
basically left with no problem at all, since when your code starts
running we would no longer have any page_cgroup allocated.

All you have to guarantee is that it happens after the memory block is
already isolated and allocations no longer can reach it.

What do you think ?
Hi Glauber,

I don't think so. We can offline some of the sections and leave the 
reset online.

For example, we store page_cgroups of memory9~11 in memory8. So when we 
offline memory8,
we free memory8's page_cgroup storing on other section, but we cannot 
free the page_cgroups
being stored in memory8 if memory9~11 are left online.

So we still need to offline memory9~11, and then offline memory8, right ?
I think it makes no difference.

Thanks. :)
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