Re: [PATCH] [Request for inclusion] Filesystem in Userspace

Bryan Henderson
2004-11-19T00:53:37Z

>but I
>think usually you have lot's of virtual memory (4Gbyte per process),
>so killing off processes to get more of it makes no sense.

I think it's fair to say you have 4G of virtual address space per process,
but try to store 4G of information per process in it, and you will
probably find you can't. What's essentially scarce is swap space. Killing
off processes frees up swap space.

It was probably wrong of me to say the OOM can't free up real memory,
because where real memory backs virtual memory, the only way to free up
the real memory is to page out the virtual memory or destroy it, and the
OOM killer destroys it.

But still -- if the real memory shortage isn't because there's no place to
page out to, but rather that the process that's supposed to be writing the
pages is deadlocked, the OOM killer will not kick in.