Bruno, have you tried or know anything about the ptlsim x86 cycle accurate simulator?
It might be a valuable tool to understand the performance of specific x86 code sequences.
Are there other similar tools? Ptlsim does not seem to be in active development (last commit in 2009). But I did get it to work... but I don't know how to analyze the results!
Is anyone interested in getting it to work, and to understand the output of ptlstats (the program that analyses the statistics gathered during execution)?
Bruno, perhaps this could be integrated to your profiling work.
Marc
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On 2011-05-17, at 11:06 , Marc Feeley wrote:
Bruno, have you tried or know anything about the ptlsim x86 cycle accurate simulator?
I only know of it, but I've never tried it.
It might be a valuable tool to understand the performance of specific x86 code sequences.
Are there other similar tools? Ptlsim does not seem to be in active development (last commit in 2009). But I did get it to work... but I don't know how to analyze the results!
IIRC, the most famous tool in the microarchitecture community seems to be SimpleScalar (http://www.simplescalar.com/). I haven't used it myself, but I've heard about it from a few sources.
Is anyone interested in getting it to work, and to understand the output of ptlstats (the program that analyses the statistics gathered during execution)?
Bruno, perhaps this could be integrated to your profiling work.
Do you mean that the simulator could be used to explain the dynamic data, or that the dynamic data can somehow enhance the simulator results (e.g. by providing some frequencies, or even validating the simulations)?
Bruno
On 2011-05-17, at 11:22 AM, Bruno Dufour wrote:
On 2011-05-17, at 11:06 , Marc Feeley wrote:
Bruno, have you tried or know anything about the ptlsim x86 cycle accurate simulator?
I only know of it, but I've never tried it.
It might be a valuable tool to understand the performance of specific x86 code sequences.
Are there other similar tools? Ptlsim does not seem to be in active development (last commit in 2009). But I did get it to work... but I don't know how to analyze the results!
IIRC, the most famous tool in the microarchitecture community seems to be SimpleScalar (http://www.simplescalar.com/). I haven't used it myself, but I've heard about it from a few sources.
Is anyone interested in getting it to work, and to understand the output of ptlstats (the program that analyses the statistics gathered during execution)?
Bruno, perhaps this could be integrated to your profiling work.
Do you mean that the simulator could be used to explain the dynamic data, or that the dynamic data can somehow enhance the simulator results (e.g. by providing some frequencies, or even validating the simulations)?
No, I simply mean that executing our code on ptlsim could provide much more detailed profiles (including branch mispredictions, cache misses, etc) than executing on a real CPU. In other words the dynamic data would be generated by an execution on ptlsim. An advantage I see is that it would eliminate the run time overhead of adding machine instructions to measure run time properties of the program, which can adversely affect the measurements. The simulator could do this with no (simulated) time overhead.
Marc
On 2011-05-17, at 11:51 , Marc Feeley wrote:
No, I simply mean that executing our code on ptlsim could provide much more detailed profiles (including branch mispredictions, cache misses, etc) than executing on a real CPU. In other words the dynamic data would be generated by an execution on ptlsim. An advantage I see is that it would eliminate the run time overhead of adding machine instructions to measure run time properties of the program, which can adversely affect the measurements. The simulator could do this with no (simulated) time overhead.
Oh, sure. I am so used to thinking of profiling in a certain way that I missed the obvious. I'll try to download and run the tools before the meeting tomorrow and let you know what I find out.
Marc, was it difficult to get ptlsim to work on your mac, or did it just run out of the box?
Bruno
On 2011-05-17, at 12:16 PM, Bruno Dufour wrote:
Marc, was it difficult to get ptlsim to work on your mac, or did it just run out of the box?
I couldn't find a version for the Mac, and I think it uses Linux specific system calls. You also have to have root permission when running ptlsim. So I compiled the sources on Ubuntu which was running virtually on baro.
Marc
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Marc Feeley