Re: pahole BRAIN FART ALERT on F12

[Mike Snitzer <snitzer@xxxxxxxxxx>]

On Mon, Nov 23 2009 at  5:49pm -0500,
Arnaldo de Melo <acme@xxxxxxxxxx> wrote:

> Em Mon, Nov 23, 2009 at 05:17:03PM -0500, Mike Snitzer escreveu:
> > Hi,
> > 
> > I just found out about pahole today.  I'm looking to audit lvm2's data
> > structures and pahole is perfect for helping me do so.
> > 
> > Unfortunately, when I run pahole against lvm2 I'm getting many BRAIN
> > FART ALERTs on F12 x86_64 (dwarves-1.7-5.x86_64).  I had a look at your
> > OLS 2007 "7 dwarves" paper and figured I'd try your minimalist
> > swiss_cheese example, this is what I get:
> > 
> > $ pahole swiss_cheese
> > struct cheese {
> >         char                       name[17];             /*     0    17 */
> >         short int                  age;                  /*     0     2 */
> >         char                       type;                 /*     0     1 */
> >         int                        calories;             /*     0     4 */
> >         short int                  price;                /*     0     2 */
> >         int                        barcode[4];           /*     0    16 */
> > 
> >         /* size: 48, cachelines: 1, members: 6 */
> >         /* padding: 32 */
> >         /* last cacheline: 48 bytes */
> > 
> >         /* BRAIN FART ALERT! 48 != 17 + 0(holes), diff = 31 */
> > 
> > };
> > 
> > When I compare the above to the output listed in your paper it is clear
> > pahole is pretty unhappy on F12.  If I do the same on F11 (x86_64) all
> > works fine.
> > 
> > Should I open a fedora (F12) bug?
> 
> You should, I think this is related to some recent elfutils changes that
> Mark Wieelard warned me about it but I hadn't time yet to act upon, will
> do so tomorrow, thanks for the report!
> 
> Some milliseconds ago I was almost going to suggest you using the git
> version, but then I realized this is too strange to seem like something
> I could have fixed in the git repository :-\
> 
> That also should be another reason for me to do the f11->f12 step :-)

Yes... embrace F12... :)

BTW, I did try the latest git version from:
git://git.kernel.org/pub/scm/linux/kernel/git/acme/pahole.git

It didn't work either.

Mike
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