Re: [PATCH V4 6/6] proc: show MADV_FREE pages info in smaps

[Shaohua Li]

On Fri, Feb 24, 2017 at 09:08:30AM -0800, Dave Hansen wrote:
> On 02/22/2017 10:50 AM, Shaohua Li wrote:
> > @@ -770,6 +774,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
> >  		   "Private_Dirty:  %8lu kB\n"
> >  		   "Referenced:     %8lu kB\n"
> >  		   "Anonymous:      %8lu kB\n"
> > +		   "LazyFree:       %8lu kB\n"
> >  		   "AnonHugePages:  %8lu kB\n"
> >  		   "ShmemPmdMapped: %8lu kB\n"
> >  		   "Shared_Hugetlb: %8lu kB\n"
> 
> I've been as guily of this in the past as anyone, but are we just going
> to keep adding fields to smaps forever?  For the vast, vast, majority of
> folks, this will simply waste the 21 bytes * nr_vmas that it costs us to
> print "LazyFree:       0 kB\n" over and over.
> 
> Should we maybe start a habit of not printing an entry when it's "0 kB"?

Interesting idea! I'd like this is a separate patch if we go this way, because
this is likely to be controversial. That said, sounds there is no reason we
shouldn't do this.

Thanks,
Shaohua