Re: Freeing boot memory

["Martin J. Bligh" <mbligh@aracnet.com>]

> I and a colleague are studying the VM subsystem (actually this is the first 
> time we are examining the Linux source code more closely) and have a question 
> or two.
> 
> Well, the questions concern the boot memory allocator. To be more precise, 
> We're interested in the memory deallocation routines. We have seen that it is 
> only possible to free full pages. So, theoretically, if we make several 
> allocations smaller than one page, we will not be able to actually free this 
> memory. I just don't know of this kind of situation happens in real life. Do 
> we currently have some pages of memory "wasted" because the boot memory 
> allocator was not able to free small allocations? Is there any estimate (or 
> benchmark or whatever) on the number of pages that could be freed but are 
> not?
> 
> We have interest in hacking a little bit in the VM, and we thought that trying 
> to find out ways to avoid this problem (if this is really a problem) could be 
> nice. Do you have any thoughts about this?

What would you *do* with this half a page? There's no main memory allocator
to stick it in, as far as I can see.

M.

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