On Tue, 2 Jun 2009, Martijn van Oosterhout wrote:
It's got nothing to do with how much swap is in use. It's preventing
you from allocating memory that *hypothetically* might not be available
if every byte of allocated memory were actually used.
For example, on my desktop I have 1GB of RAM of which about 600MB is
free, yet there is 1.4GB committed. With overcommit off my machine
may not boot. As you can see, only 25% of committed memory is actually
needed, because lots of pages are blank or shared. Ofcourse, all those
copies of libc are realistically never not going to be shared so it's a
good bet.
But with overcommit off you can see that you might want to have double
or triple the amount of swap to handle the hypothetical case.
No, sorry, I don't see why I would need more swap when I've disabled
memory overcommit. As I understand it, the kernel should be able to
allocate (swap + (physical * overcommit_ratio)), which in my case is just
swap+physical, and it seems to not want to do that.
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