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diff --git a/GPUWATTCH_README b/GPUWATTCH_README new file mode 100644 index 0000000..a122baa --- /dev/null +++ b/GPUWATTCH_README @@ -0,0 +1,163 @@ +// A Beta README file to allow folks to use GPUWattch + + +1. INTRODUCTION: + +General-purpose GPU architectures are becoming increasingly prevalent in +mainstream computing, and as such they require judicious optimization for +energy efficiency. To enable such research, we propose a new GPU power model +that offers flexibility, adaptability, and stability. Flexibility is achieved +by using a bottom-up methodology and abstracting parameters from the +microarchitectural components as model inputs. Adaptability ensures that both +program and microarchitectural level interactions are captured during +execution, thereby enabling new power-management techniques specifically +targeted at GPUs. Stability is examined by validating the power model against +measurements of two commercial GPUs comprehensively through the leakage power, +average dynamic power, and dynamic power trace. The measured error is within +9.7% and 13.6% across our evaluated benchmark suite for the two target GPUs +(GTX 480 and Quadro FX 5600 respectively) and the model accurately tracks the +relative power consumption trend over time. + +The power model modifies and extends the McPAT CPU power model simulator to +model the power of contemporary GPGPUs and drive the modified McPAT version +with a cycle-accurate simulator, GPGPU-Sim. + +2. Using the Power Model +2.1 Compiling the Power Model + +By default, GPGPU-Sim bypasses the McPAT compilation. Hence, it is not +necessary to install our modified McPAT along with GPGPU-Sim. However, if the +power model is required, our modified version of McPAT will be compiled +alongside GPGPU-Sim into libcudart.so. + +The location of McPAT is specified by the GPGPUSIM_POWER_MODEL environment +variable and is used in GPGPU-Sim's Makefile to compile McPAT. This can either +be set manually or automatically set by the setup_evironment.sh file in +<GPGPU-Sim>/distribution if McPAT is found in the default directory +(<GPGPU-Sim>/mcpat/). + +2.2. Configuration Options + +This sections lists the most relevant configuration options either to describe +model a specific architecture, model a certain improvement, or to produce extra +data from the simulation. Some of these configurations are set in the GPGPU-Sim +config files and others will be set in the McPAT XML configuration files. +GPGPU-Sim configurations mainly force specific changes to the performance +modeling itself or the output format of data, while McPAT configurations mainly +determine specific parameters for the different architectural components that +are reflected in the power modeling of these components. Here, we metion only +GPGPUsim cofigurations: + +1- power_simulation_enabled: Enablle the power model simulator; if enabled, an +output file is genarated to include the detailed Power coefficients for the +simulated configuration and the Average/Maximum/Minimum total power breakdowns +for each kernel. + +2- mcpat_xml_file: The McPAT XML configuration file name; by default it is +mcpat.xml. + +3- gpu_stat_sample_frequency: Determines the sampling frequency used in the +power calculations, the performance counters are reset before each samples and +accumulated during the sampling period, and finaly passed to the power model +(McPAT) at the end of each sample. + +4- power_trace_enabled: If enabled, it produces two output files that details +the power breakdown values, and the accumulative performance counters values +for each sample. + +5- power_per_cycle_dump: Dump detailed power data each sample + +6- steady_power_levels_enabled: If enabled, it tracks the steady state +power level throughout the execution and report the start/end values with the +average power recorded for each componenet. The steady state is determined by +(-steady_state_definition) option. + +7- steady_state_definition: Takes two values. First value detemines the allowed +deviation within the steady state and the second value determines minimum +number of samples required to assume this is a steady state power level. + + +3. Understanding Simulation Output + +In this section, we detail the fromat of the power simulator output. By +default, if the power simulation is enabled at least one output file that +reports the average/maximum/minimum power values for each kernel is produced. +More outputs can be enabled if the corresponding configurations is enabled. + + +1- gpgpusim_power_report_(date&time).log- Requires (-power_simulation_enabled +1): Includes the detailed power coefficients for this configuration and the +Average/Maximum/Minimum total power and their breakdowns for the different +components for each kernel + +2- gpgpusim_power_trace_(date&time).log.gz- Requires (-power_trace_enabled 1): +A compressed file that has a detailed average power breakdown trace in a comma +separated format + +3- gpgpusim_metric_trace_(date&time).log.gz- Requires (-power_trace_enabled 1): +A compressed file that has a detailed performance counters trace in a comma +separated format + +4- gpgpusim_steady_state_tracking_report_(date&time).log.gz- Requires +(-steady_power_levels_enabled 1): It rports the steady state power level +throughout the execution with the start/end values of each interval and the +average power recorded for each componenet during this interval in a comma +separated format + + + +5. Software Design of the Power Model + +This section presents the software design of the power model. + +5.1. File list and brief description + +In this section, we briefly describe the files that were added to interface +GPGPU-Sim with McPAT. + + +1- power_stat.cc/h @ <GPGPU_SIM>/distribution/src/gpgpu-sim/: These files +contain the main structures used for recording GPGPU-Sim performance counters: +power_core_stat_t (for all core related counters) and power_mem_stat_t (for all +memory related counters), which are contained in the wrapper power_stat_t +object. The core and mem stat structures contain multiple counter pointer +arrays with 2 locations per counter (e.g. unsigned *m_counter[2]): [0] -> +pointer to counter with the current value, [1] -> previous sampled value. The +difference, [0]-[1], is used to get the per-sample estimated power in McPAT. + +2- gpgpu_sim_wrapper.cc/h @ <GPGPU_SIM>/mcpat/: These files contain the +gpgpu_sim_wrapper class that contains all of the McPAT structures (such as +Processor, ParseXML, etc), manages the power output files, and passes the +GPGPU-Sim performance counters (described in power_stat.cc/h (1)) into McPAT. +The gpgpu_sim_wrapper structure is used in power_interface.cc/h (3) to separate +the McPAT structures and interface from GPGPU-Sim. + +3- power_interface.cc/h @ <GPGPU_SIM>/distribution/src/gpgpu-sim/: These files +are used to interface GPGPU-Sim with McPAT via two main functions: init_mcpat() +and mcpat_cycle(). init_mcpat() is called from gpgpu_sim::init() in gpu-sim.cc +and through the gpgpu_sim_wrapper object, initializes all of the power related +structures in GPGPU-Sim and McPAT. Similarly, mcpat_cycle() is called from +gpgpu_sim::cycle() in gpu-sim.cc, which passes all of the performance counters +to McPAT (through the gpgpu_sim_wrapper object). + +4- gpgpu_sim.verify @ <GPGPU_SIM>/mcpat/: This file is distributed with our +modified version of McPAT to ensure the correct McPAT version is used with +GPGPU-Sim + + + + + + + + + + + + + + + + + + |