Hi Chen, Thanks very much, the MemorySystem page really helps a lot. And I got to find many topics are covered here http://www.gem5.org/Special:SpecialPages . Another quesition, How can we get to know the configuration interfaces encapsulated in python, I mean, for example we always see the lines:import m5from m5.objects import *but where are the definitions for m5 and all the objects? they seem to be built-in in the binary executable, and the scripts under gem5/configs have just exposed part of it, and I do not known what to do when trying to add a LLC. why don't we provide a much detailed API or something. Thanks.Date: Mon, 28 Jan 2013 08:38:03 -0800 From: chen.t...@acm.org To: gem5-users@gem5.org Subject: Re: [gem5-users] how to start gem5
Benlong, Maybe I can also help you a little bit as a new user of gem5 who started to learn it about two weeks ago. Here are several things I did to get started. 1. Start with Introduction http://gem5.org/Introduction. Compile gem5 for the architecture you are interested, try it with pre-compiled helloworld binary. 2. When you are able to finish the "helloword" simulation, it's a good idea to spend time in documents http://gem5.org/Documentation and tutorials http://gem5.org/Tutorials. "Getting start" section and "Running gem5" section are must reads. However, it may be quite hard to understand everything, but you just need to make sure you know what these articles and tutorial slides are talking about at high level. I actually quite like the figure on memory system: http://www.gem5.org/docs/html/gem5MemorySystem.html While you read the documents, you can try to run some experiments yourself. For example, different scripts in configs/example, different modes (FS/SE), different workloads, different simulation models (simple atomic, simpletiming, InOrder, O3) etc.. 3. After finish first-round reading and blackbox testing, you can dig into code. I started from http://gem5.org/SimObjects. I myself is not familiar with python too, but I don't think it's hard to read it as long as you have experience in other languages. If there is some keywords, syntax or grammar you don't understand, go to google or search on http://www.python.org/. For C++ part, I think if you know C and OO concept, it should not be a big problem either -- certain things I don't like about C++ such as templates are used in several places, and may cost you sometime to understand. While reading source code, I usually keep instrumenting it with printf and run it with helloword binary so I can keep tracking the control flow. Of course, don't simulate a complex system, simpleatomic is good enough. The only problem I have is compiling gem5 takes too much time. It took me over 20 minutes to build everything on my Dell Precision workstation. So when you insert printf, try to avoid places like header files. Also try to use 64-bit system as more memory can be used -- it seems gem5 needs a lot of memory to compile. 4. After you have basic understanding in how a python config file is used to instantiate C++ object and how a simulation is started, you can spent time in the part you are interested -- whether it's cache or memory, or pipelined cpu. Gem5 has many nice designs that you may not find from other simulators, I myself is also learning. Also, mailing list is always helpful, and you can post your questions if you get stuck. Best,Chen On Mon, Jan 28, 2013 at 7:10 AM, Benlong Zhang <zblgeq...@outlook.com> wrote: Hi, all, I've recently just begun to learn and use gem5, and become really interested in the inside mechanisms and details. and I also want to learn about the system architecture from reading the code of m5. however, it's such a big (though not so big, when compared to, perhaps Linux kernel)project. because not familiar with the python and cpp, and the two seems to be tightly coupled. I feel quite miserable when reading the code. Do i need to go throughthe project line by line, or just need to read certain part of it in order to grasp the main frame and make some modifications according to real needs? and is there any valuable advice on how to read the codes, especially the coupled part between python and cpp ? Thanks so much.--------------------------------------------------------------------Benlong Zhang, Beijing, CHina _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
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