Re: [patch 2/2] procfs: provide stack information for threads V0.10

Ingo Molnar
2009-06-24T17:46:58Z

* Johannes Weiner <hannes@cmpxchg.org> wrote:

> On Wed, Jun 24, 2009 at 05:49:50PM +0200, Stefani Seibold wrote:
> > Am Mittwoch, den 24.06.2009, 17:20 +0200 schrieb Ingo Molnar:
> > > * Stefani Seibold <stefani@seibold.net> wrote:
> > >
> > > > Hi,
> > > >
> > > > this is the newest version of the formaly named "detailed stack info"
> > > > patch which give you a better overview of the userland application stack
> > > > usage, especially for embedded linux.
> > > >
> > > > Currently you are only able to dump the main process/thread stack usage
> > > > which is showed in /proc/pid/status by the "VmStk" Value. But you get no
> > > > information about the consumed stack memory of the the threads.
> > > >
> > > > There is an enhancement in the /proc/<pid>/{task/*,}/*maps and which
> > > > marks the vm mapping where the thread stack pointer reside with "[thread
> > > > stack xxxxxxxx]". xxxxxxxx is the maximum size of stack. This is a
> > > > value information, because libpthread doesn't set the start of the stack
> > > > to the top of the mapped area, depending of the pthread usage.
> > > >
> > > > A sample output of /proc/<pid>/task/<tid>/maps looks like:
> > > >
> > > > 08048000-08049000 r-xp 00000000 03:00 8312 /opt/z
> > > > 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/z
> > > > 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
> > > > a7d12000-a7d13000 ---p 00000000 00:00 0
> > > > a7d13000-a7f13000 rw-p 00000000 00:00 0 [thread stack: 001ff4b4]
> > >
> > > I have the same question as before: have you checked the use of that
> > > field in tools/perf/builtin-record.c, and how your change will
> > > impact that?
> > >
> >
> > Good question... i have another one: What is
> > tools/perf/builtin-record.c and where can i find it? Then i
> > could check it.
>
> You can find it in a recent git tree from Linus.
>
> On the original question: builtin-record.c is unaffected by this
> patch as this exact field will only be parsed if the mapping is
> executable.

A stack can be executable too. It is not common, but possible.

Ingo