>
> using 6574 buffers containing 26296 KB of memory
>
>  (these numbers are for machine with 0.5Gb of RAM). Please feel free to
>  correct me if I'm wrong - I'm not VM expert.
I think you are wrong. 26296KB of memory is statically allocated to keep
metadata (directories, inodes, bitmaps), while everything else is
allocated dynamically and competes with program data and text pages.
there are some tuning options which were mentioned in tech-kernel about
setting min and max of memory allocated to dynamic buffers in -current,
but i'm not tracking current now.