>
> > Peanuts, it takes 3mb of page tables to map all the physical pages of
> > ram into kernel space on my SMP Sparc box.
>
> Which is too much unpageable data. Page tables are meant to be paged.
trying to estimate the memory accounting overhead for Linux:
is this formula right?:
N: number of i386 tasks (processes)
MEM: average size of a task, in pages
a page table entry is 32 bits = 4 bytes
the size of the page tables (hardware page tables only):
N*MEM*4*FACTOR,
where FACTOR is a near 1.0 multiplier, because of the root page table.
lets take 10 heavy tasks, each with 4MBytes of virtual memory:
This would be 10*1024*4 = 10 pages .... something is wrong here :) Where
are those big page tables you are talking about? [my fault most probably]
Or do you mean the memory overhead caused by Linux memory management,
vma-s, free lists, buffer heads? [dont know how big they are]
-- mingo