Subject: Re: pmap l1pt allocation strategy
To: <>
From: David Laight <>
List: port-arm
Date: 11/28/2002 10:32:50
> But the fundamental problem is that there is no way to ask the paging 
> system to free up a 16K-aligned block of memory -- all you can ask for is 
> 4 pages, so we end up in the situation where the paging system thinks 
> there are enough free resources, but the vm system doesn't.

To avoid a complete rewrite of the paging system, could you timeout
and retry, asking the paging system for more free pages each time?

Make fork should fail EAGAIN after a timeout as well?

But swapping them (or stealing one from an idle process?)
may be better.

Thinking about the free list, I'm not sure keeping entries in case
you can't allocate 1 would be an advantage.
You would have the preserve the last entry for root, and probably
for an interactive shell that isn't in a fork bomb...

The freelist is (presumably) there to avoid the expensive allocate
when running shell scripts (etc).


David Laight: