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List:       freebsd-hackers
Subject:    Re: pahole - Finding holes in kernel structs
From:       Joseph Koshy <jkoshy () freebsd ! org>
Date:       2009-02-15 13:59:41
Message-ID: 86skmfztrm.wl%koshy () unixconsulting ! co ! in
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> Well, I think we want to inform this through actual measurement.  Right now, 
> tools like hwpmc track cache misses by point in executable code, but what 
> would be nice is if we could post-process to generate cache miss information 
> by data structure field...

That is one of the tools that I've had in mind.

The hard part in the process is tracking sample locations back to
source artifacts with acceptable accuracy.  I couldn't find existing
libraries with a compatible open-source license that I could build on,
and thus the motivation for some of the libraries listed in the
roadmap at http://elftoolchain.sourceforge.net/.

Also, hwpmc(4) would need to be augmented to use "precise" sampling on
the hardware that supports it, but this is relatively straightforward.

Koshy
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