HotLeakage Simulator Pre-Release Version 1.0. --------------------------------------------- OVERVIEW: README.HotLeakage is for HotLeakage Pre-Release 1.0. It is a tool for modeling leakage current for cache-like structures. It is built upon Wattch Power Performance simulator. Currently it is implemented to model the leakage of caches and register file only. Though adding models for other cache-like structures is very simple. It models both sub-threshold and gated leakage. This model also
takes care of the inter-die variations in different parameters like voltage,
technology etc. HotLeakage 1.0 can be downloaded from: http://lava.cs.virginia.edu/HotLeakage
We have merged the HotLeakage list into the HotSpot list. This e-mail list is for the exchange of comments, questions, and answers among users regarding the HotLeakage or HotSpot models. The HotLeakage authors will try to monitor this list and respond to questions as quickly as possible.
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DOCUMENTS: *The technical report describes in details the derivation of the model and the tool in general. *README.HotLeakage is the general README. *README.HotLeakage.Howto.FAQ is the document that describes how to use the tool and how to use it to model another structure etc. *README.HotLeakage.TODO is the list of things to be done for the final version. *README_Hotleakage_Model.doc describes the circuit simulations one needs to do for adding another structure or modeling for a different technology. TO INSTALL: HotLeakage should compile on any system that SimpleScalar compiles on. Testing/development was primarily done with the ALPHA version.
It was verified that the tool should compile on both PISA and ALPHA but otherwise no testing has been done with PISA. We already know of one change that should be made when using PISA: Comment out the line in main.c: "sim_num_insn -= 2000000000;" and uncomment the line "//sim_num_insn -= fastfwd_count;" It should be straightforward to modify HotLeakage into a completely modular form such that any simulator infrastructure can use it. Note that HotLeakage is primarily designed to
be used with sim-outorder (the full processor simulator). It does not
support sim-fast, sim-cache, etc (although adding some simple power
estimates for these faster simulators would be very easy). Thus you
should only need to run "make sim-outorder" and in fact you will get
errors if you try to compile the other simulators because they are
missing some external variable declarations.
For correct compilation on any systems please follow the following steps: 1. gmake symlinks 2. gmake config-<alpha/pisa> 3. gmake clean 4. gmake Both gmake and make should work. Please note the first step which is different from the normal SimpleScalar compilation. SIMULATION AND RESULTS: Running HotLeakage should be just like running sim-outorder. Provide it with your processor configuration parameters, input binary, and input data set. There are lots of separate processor configuration parameters for leakage modeling. Please see the hotleak_alpha_config.cfg file for
more details. Please NOTE that currently the Technology parameter needs
not only be provided in the command line but also needs to be hardcoded
in powerinit.c ( in the function power_reg_options).This will be fixed
in the final release. These are the additional statistics that are generated by HotLeakage: In the beginning of the simulation all the leakage currents are calculated (Currently only the register file and the caches). The leakage currents for each component (for e.g. for a cache, the data array, tag-array, decoders etc ) are printed. In the code (leakage.c) look out for leakage_power->dl1_data etc. for the data structures that store these values. CHANGES: This version has some cache leakage saving techniques (like drowsy , gatedVss) being modeled for the caches. The user has the option to choose any or none of these techniques. Additional leakage saving mechanisms can be modeled and the HotLeakage leakage model can be used. Some highlights of the major changes from the basic Wattch 1.0 release. 1). Leakage.c and leakage.h These files contain the core of HotLeakage leakage model. double nmos_ileakage(double aspect_ratio, double Volt, double Vth0, double Tkelvin, double tox0) double pmos_ileakage(double aspect_ratio, double Volt, double Vth0, double Tkelvin, double tox0) These two above functions are the main functions that calculate the leakage of one P and N transistor. Depending on the circuit one can call these to calculate the leakage of one cell of a structure. Here there are five main parameters that a user can vary to model different scenarios. *Aspect Ratio. *Voltage. *Threshold Voltage. *Temperature. *Toxide Thickness. 2). Leakinit.c This module initializes all the technology parameters for different technologies. If the user wants to calculate the leakage of a different structure he or she will have to do the circuit simulations as mentioned in the README__HotLeakage_Model.doc and then feed the parameters in this module. 3). Power.c and powerinit.c and power.h Power.c is mainly the same. Power.h has been broken for ease of usage into powerinit.c and power.h Cacti libraries (in cacti subdirectory): This is the Cacti distribution. It is used in power.c to perform automatic delay-optimial cache partitioning. Some of the low-level routines to compute gate/diffusion capacitance of transistors are also shared. Leakage.c also uses it for for the leakage calculation of caches. 4). Cache.c This is modified to model different cache leakage saving mechanisms. If you use none then you should not be concerned about it. 5). Cache_leak_ctrl.c and cache_leak_ctrl.h Again these files are for the different cache leakage saving mechanisms. Please see the TODO list for the things to be added in the final release. Please send your comments and any bugs to: Email: email@example.com We are continually trying to improve it to release it in its final form.