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SubjectRe: Overcommitable memory??
On Fri, 17 Mar 2000, James Sutherland wrote:
>On Fri, 17 Mar 2000, David Whysong wrote:

>> what do you mean by "free" memory?
>
>Well, the kernel's definition is:
>free = (buffermem >> PAGE_SHIFT) + (page_cache_size + nr_free_pages +
> nr_swap_pages) - (page_cache.min_percent + buffer_mem.min_percent
> +2)*num_physpages/100;
>
>It then returns (free > pages), where pages was the number of pages
>requested. (If sysctl_overcommit_memory is non-zero, it ALWAYS returns 1,
>bypassing the above checks.)

Ok, this makes sense.

>Close - but it's not the TOTAL RAM+swap, it's the FREE RAM+swap. Your
>experiment indicated you had managed to malloc() more than this, though,
>even with sysctl_overcommit_memory == 0?

Not when you subtract out buffer memory and the page cache, as above...

Dave

David Whysong dwhysong@physics.ucsb.edu
Astrophysics graduate student University of California, Santa Barbara
My public PGP keys are on my web page - http://www.physics.ucsb.edu/~dwhysong
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