Performance Counter Addresses

Downing, Evan P edowning3 at
Mon Oct 5 01:52:30 UTC 2015

I'm gathering data such as network traffic, plugins installed, files downloaded using Firefox, etc.

I could just use PANDA, but extracting the information could take a long time.

The performance overhead is large.

It would be faster if I used rr to extract preliminary information to determine if the data is worth studying more, and then perform an in-depth analysis using PANDA.

Sort of like zooming in on the problem (using PANDA) once I've discovered it (using rr).


From: rocallahan at <rocallahan at> on behalf of Robert O'Callahan <robert at>
Sent: Sunday, October 4, 2015 9:46 PM
To: Downing, Evan P
Cc: Kyle Huey; rr-dev at
Subject: Re: Performance Counter Addresses

On Mon, Oct 5, 2015 at 2:40 PM, Downing, Evan P <edowning3 at<mailto:edowning3 at>> wrote:
> We don't use them by default.  There is a flag in PerfCounters.h
> determining whether or not to use the extra counters.  I think this is
> mostly a legacy of early experiments to move from
> retired-conditional-branches to instructions-retired that are
> essentially abandoned at this stage.


> Can you use rr *outside* of QEMU?  And just record all of QEMU?

To clarify a bit more: I am trying to use PANDA and rr together on a project to study the activities of Firefox. During this project I want to use rr as a coarse-grained analysis tool and PANDA as a fine-grained analysis tool. Because I'm using PANDA as a fine-grained analysis tool, I must have it running as rr is running inside the Linux guest. Unfortunately, PANDA is based on QEMU 1.0.1 and is not able to use KVM to record and replay QEMU activity.

How should I combine these tools together to analyze Firefox's activities?

What kind of data are you trying to gather? It would seem to me that you can just use PANDA and ignore rr.

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