HotSpot 1.0 - Information Manual -------------------------------- CONTENTS -------- 1) License 2) Introduction 3) Installation 4) Using HotSpot 5) Contact (E-mailing list) 6) References LICENSE ------- LICENSE TERMS Copyright (c)2003 Wei Huang, Sivakumar Velusamy, Karthik Sankaranarayanan, David Tarjan, Mircea R. Stan, and Kevin Skadron. All rights reserved. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this software and its documentation for any purpose, provided that the above copyright notice and the following four paragraphs appear in all copies of this software, whether in binary form or not. IN NO EVENT SHALL THE AUTHORS, THE UNIVERSITY OF VIRGINIA, OR THE STATE OF VIRGINIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE AUTHORS, THE UNIVERSITY OF VIRGINIA, AND THE STATE OF VIRGINIA SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE AUTHORS HAVE NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. NEITHER THE NAME OF ANY VIRGINIA ENTITY NOR THE NAMES OF THE CONTRIBUTORS MAY BE USED TO ENDORSE OR PROMOTE PRODUCTS DERIVED FROM THIS SOFTWARE WITHOUT SPECIFIC PRIOR WRITTEN PERMISSION. If you use this software or a modified version of it, please cite the following paper: K. Skadron, M. R. Stan, W. Huang, S. Velusamy, D. Tarjan, and K. Sankaranarayanan. "Temperature-Aware Microarchitecture." In Proceedings of the 30th International Symposium on Computer Architecture, June 2003 INTRODUCTION ------------ HotSpot is a computationally efficient, architecture level thermal modeling infrastructure developed at the University of Virginia. It makes use of the duality that exists between the electrical and thermal properties of materials to model processor temperature. It is written in 'C' and can be easily interfaced with typical power/performance simulators available in the community. It can be downloaded from http://lava.cs.virginia.edu/HotSpot INSTALLATION ------------ 1. Download the HotSpot tar ball (HotSpot-1.0.tar.gz) following the instructions at http://lava.cs.virginia.edu/HotSpot 2. Unzip and untar the file using the following commands a) gunzip HotSpot-1.0.tar.gz b) tar -xvf HotSpot-1.0.tar 3. Go to the HotSpot installation directory a) cd HotSpot-1.0/ 4. Set the appropriate compiler flags and options in the Makefile 5. Build HotSpot a) make (or) make sim-template 6. Run the demo simulator - no errors should be detected a) ./sim-template 7. To remove all the outputs of compilation, type 'make clean'. To remove the object files alone, type 'make cleano'. To view the list of files HotSpot needs for proper working, type 'make filelist'. USING HOTSPOT ------------- HotSpot models the temperature of a microprocessor at the granularity of a Functional Unit Block (FUB) by making use of the duality that exists between heat flow and electricity. It constructs an RC network of thermal resistances and capacitances of the FUBs and uses circuit solving techniques to obtain the temperatures at the centers of the FUBs. In order to obtain a proper understanding of the working of HotSpot, the user is urged to refer to the ISCA paper [1] and the Technical Report [2] before proceeding to further sections of this manual. HotSpot software has the following files: 0. Makefile - for building HotSpot 1. RC.h, temperature.c, RCutil.c - these are the core temperature modeling modules. - RC.h exports the various temperature modeling function interfaces and globals. - RCutil.c provides numerical routines for matrix computation and solving partial differential equations. - temperature.c creates the RC matrices based on the processor floorplan and other specifications. It uses RCutil.c to solve the circuit. It contains the two core functions for transient and steady state temperature modeling - 'compute_temp' and 'steady_state_temp'. 2. flp.h and flp.c - the floorplanning module. - This reads the floorplan description of the processor from a file (ev6.flp) and provides the area and adjacency information required by temperature.c through function calls. 3. sim-template.c - demo simulator to illustrate the use of HotSpot. - It demonstrates the use of HotSpot to obtain steady state and transient temperature numbers through a simple 'main' function that uses sample power numbers from our test run of the SPEC2000 gcc benchmark. It also provides dummy 'sim_*' functions which outline the possible use of HotSpot within a cycle-based power/performance simulator. 4. util.h and util.c - miscellaneous utilities for printing error messages, finding max of two numbers etc. 5. ev6.flp - floorplan description input file - This is the floorplan used in the sim-template demo simulator. It closely resembles the floorplan of the Alpha EV6 microprocessor. 6. gcc.init - sample initial temperatures input file - The transient modeling in HotSpot requires the initial temperatures to be set to proper values. One approach (ignoring the effect of multiprogramming) is to set the steady state temperatures to be the initial temperatures. This file gives the steady state temperatures computed using the power numbers obtained from our test run of the SPEC2000 gcc benchmark. These temperatures form the initial temperatures of the sim-template demo simulator. 7. tofig.pl - perl script to produce viewable floorplan output - This script takes the output of sim-template (produced by the floorplan module called within) and outputs the floorplan in a '.fig' file format that can be displayed and converted using the xfig program. The two functions 'compute_temp' and 'steady_state_temp' defined in temperature.c form the core of HotSpot. They model the transient and steady state temperatures respectively. However, using HotSpot involves the following Initialization steps to be performed BEFORE using these functions: a) Initialization of chip and package specs and other globals - The externs defined in RC.h viz. chip dimensions, spreader dimensions, heat sink dimensions, convection resistance and capacitance, ambient temperature and thermal trigger threshold are to be initialized with the proper desired values. b) Initialization of the floorplan - The floorplan input file is specified in a particular format. Each FUB's position and dimensions are specified in a single line. The format of a line describing an FUB is '<unit-name>\t<width>\t<height>\t<left-x>\t<bottom-y>'. Comment lines begin with a '#' and are ignored. Empty lines are also ignored. In order to initialize the floorplan module, the 'read_flp' function is called with the floorplan input filename as the parameter. c) Creation of the RC matrices - This is done by calling 'create_RC_matrices' and passing the pointer to the floorplan structure returned by the 'read_flp' function. If the lateral resistances component of the RC network should be ignored, then the second parameter (int omit_lateral) is set to a non-zero value. d) Allocation of memory for the temperature and power vectors - It is to be noted that the order of the FUBs in the temperature and power vectors is the same as that of the floorplan input file. However, the index of a particular FUB within the power or temperature vector could also be obtained by calling 'get_blk_index' with the FUB-name as the parameter. Since HotSpot creates extra nodes in the RC network (corresponding to the spreader and heat sink), the size of the power and temperature vectors is larger than the number of FUBs. Hence, memory for the vectors has to be allocated only through HotSpot. The function that does this is 'hotspot_vector'. e) Setting up initial temperatures (for 'compute_temp') - As mentioned above, transient modeling requires the initial temperature values to be set properly. HotSpot provides two functions to accomplish this - 'read_temp' and 'set_temp'. 'read_temp' reads initial temperatures from a file that was previously output using the 'dump_temp' routine. Note that if the number of FUBs has changed between the 'dump_temp' and the 'read_temp', then the 'read_temp' could get incorrect values. So, each time FUBs are added or removed to the floorplan, the initial temperatures have to be regenerated. 'set_temp' is useful when the steady state output of a previous run is not available. 'set_temp' sets the temperatures of all FUBs and internal nodes to a single value which is passed as a parameter. When a new application is run with HotSpot, a typical sequence in determining the proper initial temperatures is: - Run the application with all internal nodes and FUBs set to a fixed initial temperature (say 60C). - Dump the steady state temperatures at the end of the above run. This is done using the 'dump_temp' function. - Use the above dumped temperatures as the initial temperatures for the next run. - If the power numbers are dependent on temperature (for eg. if leakage effects on temperature are modeled), continue the previous two steps until the temperatures converge. Note that when power numbers are available off-line, sim-template can be used to compute the steady state and hence the initial temperatures. The power numbers in 'main' need to be set accordingly and 'init_file' needs to be set to NULL for the first time. The output sim-template prints and the file written by 'dump_temp' called in 'main' contain the proper initial temperatures for the next run. Once these initialization steps are performed, using HotSpot is straightforward. When average overall power numbers are available, they are passed onto 'steady_state_temp' to obtain the steady state temperatures. Similarly, 'compute_temp' is called at regular intervals by passing in the time elapsed during the interval and the power numbers for that interval. When the initial temperatures are set properly, 'compute_temp' advances the temperatures by an amount corresponding to the time elapsed. Successive calls to 'compute_temp' with the same temperature vector give the transient behavior of the processor's temperature. HotSpot also provides some uninitialization routines that could be called at the end of temperature modeling (cleanup_hotspot, free_flp and free_vector). These free up the memory allocated for the internal data structures. CONTACT (E-MAILING LIST) ------------------------ HotSpot can be downloaded following the instructions at http://lava.cs.virginia.edu/HotSpot. In order to exchange comments, questions and answers amidst the users of HotSpot, we have created an e-mailing list. We will try to monitor this list and respond to questions as quickly as possible. One can subscribe to this list by visiting http://www.cs.virginia.edu/mailman/listinfo/hotspot . This list is archived and messages can be sent to it by e-mailing 'hotspot at cs dot virginia dot edu' REFERENCES ---------- [1] K. Skadron, M. R. Stan, W. Huang, S. Velusamy, K. Sankaranarayanan, and D. Tarjan. "Temperature-Aware Microarchitecture", In Proceedings of the 30th International Symposium on Computer Architecture, June 2003. [2] K. Skadron, M. R. Stan, W. Huang, S. Velusamy, K. Sankaranarayanan, and D. Tarjan. "Temperature-Aware Microarchitecture: Extended Discussion and Results", University of Virginia Technical Report CS-2003-08, June 2003.
