linux-kernel - Re: frame unwinder patches

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Message-ID: <20080905094316.GS18288@one.firstfloor.org>
Date:	Fri, 5 Sep 2008 11:43:16 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Bernd Schubert <bs@...eap.de>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	jbeulich@...ell.com
Subject: Re: frame unwinder patches

On Fri, Sep 05, 2008 at 11:24:16AM +0200, Bernd Schubert wrote:
> On Thursday 04 September 2008 21:13:58 Andi Kleen wrote:
> > Bernd Schubert <bs@...eap.de> writes:
> > > Hello,
> > >
> > > up to 2.6.22 the -mm series had these nice frame unwinder patches,
> > > which gave beautiful stack traces. Unfortunately these frame unwinder
> > > patches seem to have been dropped :(
> > >
> > > Anyone still maintaining updated patches?
> >
> > The SUSE kernel rpm should have an uptodate set
> >
> > (ftp.suse.com/pub/projects/kernel/HEAD )
> >
> 
> Thanks Andi, found it! If someone else needs it, the correct path is 
> ftp://ftp.suse.com/pub/projects/kernel/kotd/HEAD. 

Thanks for the correction.

> > I agree that they were much better than the current unwinder,
> > also they didn't require slowing down the kernel with
> > frame pointers.
> 
> What it the reason this patch isn't mainline? It provides better traces, 
> doesn't slow down the kernel (which is important in our HPC envirement), so 
> what is the disadvantage?

The initial version that was merged had a few teething problems because
it ran into tool chain bugs (which were quickly resolved). Unfortunately 
it lead to a few people developing irrational fears of dwarf2 in the 
process and it was reverted, annoying the original contributor.
Right now someone would just need to retry the submission I guess.

-Andi

-- 
ak@...ux.intel.com
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