Re: [patch 3/8] slub: Update statistics handling for variable order slabs

["Pekka Enberg" <penberg@cs.helsinki.fi>]

Hi Christoph,

On Fri, Feb 29, 2008 at 9:43 PM, Christoph Lameter <clameter@sgi.com> wrote:
>  Hmmm... I get some weird numbers when I use slabinfo but cannot spot the
>  issue. Could you look a bit closer at this? In particular at the slabinfo
>  emulation?

What kind of weird numbers? Unfortunately the patch still looks
correct to me so it might be an integer overflow issue...

On Fri, Feb 29, 2008 at 6:48 AM, Christoph Lameter <clameter@sgi.com> wrote:
>  @@ -4331,7 +4367,9 @@ static int s_show(struct seq_file *m, vo
>         unsigned long nr_partials = 0;

nr_partials is no longer read so you can remove it.

>         unsigned long nr_slabs = 0;
>         unsigned long nr_inuse = 0;

No need to initialize nr_inuse to zero here.

>  -       unsigned long nr_objs;
>  +       unsigned long nr_objs = 0;
>  +       unsigned long nr_partial_inuse = 0;
>  +       unsigned long nr_partial_total = 0;
>         struct kmem_cache *s;
>         int node;
>
>  @@ -4345,14 +4383,15 @@ static int s_show(struct seq_file *m, vo
>
>                 nr_partials += n->nr_partial;
>                 nr_slabs += atomic_long_read(&n->nr_slabs);
>  -               nr_inuse += count_partial(n);
>  +               nr_objs += atomic_long_read(&n->total_objects);

So does ->total_objects contain the total amount of objects (not
necessarily in use) including the partial list or not? AFAICT it
_does_ include slabs in the partial list too so nr_objs is correct
here.

>  +               nr_partial_inuse += count_partial_inuse(n);
>  +               nr_partial_total += count_partial_total(s, n);
>         }
>
>  -       nr_objs = nr_slabs * s->objects;
>  -       nr_inuse += (nr_slabs - nr_partials) * s->objects;
>  +       nr_inuse = nr_objs - (nr_partial_total - nr_partial_inuse);

So if nr_objs contains the total number of objects in all slabs
including those that are in the partial list, this looks correct also.

                             Pekka

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