Re: How do you accurately determine a process' RAM usage?

[Andrew Morton <akpm@osdl.org>]

P@draigBrady.com wrote:
>
> Andrew Morton wrote:
> > Calculating this stuff accurately is very expensive.  You'll get a better
> > answer using proc-pid-smaps.patch from -mm, but even that won't tell you
> > things about sharing levels of the pages.
> 
> Great, thanks! I'll play around with this:
> http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.13-rc1/2.6.13-rc1-mm1/broken-out/proc-pid-smaps.patch

OK, please let us know how it goes.

> Looks like it's been stable for 4 months?

yup, although I don't think it's been used much.

> Given that it's an independent /proc/$pid/smaps file,
> it only needs to be queried when required and so
> I wouldn't worry too much about cost. `top` wouldn't use it
> for e.g., but specialised tools like mine would.

I agree, but people get upset ;)

Plus some userspace tool developer might see it and start using it without
knowing the cost on big iron.