Re: [RFC Patch] getrusage: fill ru_ixrss, ru_idrss and ru_isrss fields

[Cong Wang <amwang@redhat.com>]

KOSAKI Motohiro wrote:
>> KOSAKI Motohiro wrote:
>>> 	The next three fields, the subject of this patch, are named ru_XXrss:
>>> 	though the 80-column comment omits to say "resident set" before "size",
>>> 	I believe they'd be expected to account (subdivided) resident set sizes?
>>>
>>>
>>> your calculation is not rss nor not integral.
>>>
>> Hmm, I misunderstood rss here. Does it mean the memory stayed in
>> physical mem? i.e. not swapped out.
> 
> Yes.
> 
> Plus, 'integral' mean "tick * rss". but in dyntick environment, per tick statistics is not
> so easy nor low cost.

Thanks for explanation!

> 
>> So, if I want to get those rss statistics, I have to add some more
>> mm_counter by myself? I only find file_rss and anon_rss in mm_struct.
> 
> Hmm..
> I doubt nobody use such statistics. if nobody explain real world usage, I oppose to add
> new counter overhead.

Well, this is one of the usages. :)

I just checked more, I found it's not easy to add rss statistics for
stack, executable, etc... the reason is that we don't have a page flag
to mark a page as used for stack etc.