Re: [PATCH] hugetlb: /proc/meminfo shows data for all sizes of hugepages

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 07 Mar 2011 11:46:54 -0800
Dave Hansen <dave@linux.vnet.ibm.com> wrote:

> On Mon, 2011-03-07 at 14:05 +0100, Petr Holasek wrote:
> > +       for_each_hstate(h)
> > +               seq_printf(m,
> > +                               "HugePages_Total:   %5lu\n"
> > +                               "HugePages_Free:    %5lu\n"
> > +                               "HugePages_Rsvd:    %5lu\n"
> > +                               "HugePages_Surp:    %5lu\n"
> > +                               "Hugepagesize:   %8lu kB\n",
> > +                               h->nr_huge_pages,
> > +                               h->free_huge_pages,
> > +                               h->resv_huge_pages,
> > +                               h->surplus_huge_pages,
> > +                               1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
> >  }
> 
> It sounds like now we'll get a meminfo that looks like:
> 
> ...
> AnonHugePages:    491520 kB
> HugePages_Total:       5
> HugePages_Free:        2
> HugePages_Rsvd:        3
> HugePages_Surp:        1
> Hugepagesize:       2048 kB
> HugePages_Total:       2
> HugePages_Free:        1
> HugePages_Rsvd:        1
> HugePages_Surp:        1
> Hugepagesize:    1048576 kB
> DirectMap4k:       12160 kB
> DirectMap2M:     2082816 kB
> DirectMap1G:     2097152 kB
> 
> At best, that's a bit confusing.  There aren't any other entries in
> meminfo that occur more than once.  Plus, this information is available
> in the sysfs interface.  Why isn't that sufficient?
> 
> Could we do something where we keep the default hpage_size looking like
> it does now, but append the size explicitly for the new entries?
> 
> HugePages_Total(1G):       2
> HugePages_Free(1G):        1
> HugePages_Rsvd(1G):        1
> HugePages_Surp(1G):        1
> 

Let's not change the existing interface, please.

Adding new fields: OK.
Changing the way in whcih existing fields are calculated: OKish.
Renaming existing fields: not OK.