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vmguarpages != oomguarpages ? [message #37398]

Sun, 06 September 2009 20:29

divB
Messages: 79
Registered: April 2009

Member

Hi,

Let us assume a (hypothetical) HN with 1GB RAM and 10 VEs. For the sake of simplicity we do not care about kernel mem, buffers, hardware node...so we can give every hardware node 100 MB. And I want to guarantee each container 100 MB.

If I want to make sure that every container is guaranteed 100 MB of RAM I have to set vmguarpages to 100 MB, haven't I?!

Because let's assume that all memory malloced is actually used we would face a problem and we could not guarantee 100 MB of RAM?!

But on the other hand, oomguarpages tells the guaranteed pages in an out of memory contition or in a different way: The guarantee of actual used pages (i.e. malloced and used).

So I must conclude that I have to always set oomguarpages = vmguarpages in order to ensure each VE is guaranteed 100 MB?

Is this correct or do I get something wrong? Is there a good reason to set oomguarpages to 100 MB and vmguarpages to 120 MB in my hypothetical example?

When hosting providers talk about memory guarantee: Do they mean the guaranteed amount of malloc-able memory (i.e. vmguarpages) or do they mean the guaranteed amount of useable memory (i.e. oomguarpages)?

Regards,
divB

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