An open-source gymnasium for machine studying assisted pc structure design – Google Analysis Weblog


Pc Structure analysis has an extended historical past of creating simulators and instruments to guage and form the design of pc methods. For instance, the SimpleScalar simulator was launched within the late Nineties and allowed researchers to discover numerous microarchitectural concepts. Pc structure simulators and instruments, resembling gem5, DRAMSys, and plenty of extra have performed a major function in advancing pc structure analysis. Since then, these shared sources and infrastructure have benefited trade and academia and have enabled researchers to systematically construct on one another’s work, resulting in important advances within the subject.

Nonetheless, pc structure analysis is evolving, with trade and academia turning in the direction of machine studying (ML) optimization to satisfy stringent domain-specific necessities, resembling ML for pc structure, ML for TinyML accelerationDNN accelerator datapath optimization, reminiscence controllers, energy consumption, safety, and privateness. Though prior work has demonstrated the advantages of ML in design optimization, the dearth of robust, reproducible baselines hinders truthful and goal comparability throughout completely different strategies and poses a number of challenges to their deployment. To make sure regular progress, it’s crucial to grasp and sort out these challenges collectively.

To alleviate these challenges, in “ArchGym: An Open-Supply Gymnasium for Machine Studying Assisted Structure Design”, accepted at ISCA 2023, we launched ArchGym, which incorporates a wide range of pc structure simulators and ML algorithms. Enabled by ArchGym, our outcomes point out that with a sufficiently massive variety of samples, any of a various assortment of ML algorithms are able to find the optimum set of structure design parameters for every goal downside; nobody answer is essentially higher than one other. These outcomes additional point out that deciding on the optimum hyperparameters for a given ML algorithm is important for locating the optimum structure design, however selecting them is non-trivial. We launch the code and dataset throughout a number of pc structure simulations and ML algorithms.

Challenges in ML-assisted structure analysis

ML-assisted structure analysis poses a number of challenges, together with:

  1. For a selected ML-assisted pc structure downside (e.g., discovering an optimum answer for a DRAM controller) there isn’t a systematic option to establish optimum ML algorithms or hyperparameters (e.g., studying charge, warm-up steps, and so on.). There’s a wider vary of ML and heuristic strategies, from random stroll to reinforcement studying (RL), that may be employed for design house exploration (DSE). Whereas these strategies have proven noticeable efficiency enchancment over their selection of baselines, it’s not evident whether or not the enhancements are due to the selection of optimization algorithms or hyperparameters.
    Thus, to make sure reproducibility and facilitate widespread adoption of ML-aided structure DSE, it’s crucial to stipulate a scientific benchmarking methodology.
  2. Whereas pc structure simulators have been the spine of architectural improvements, there may be an rising want to handle the trade-offs between accuracy, pace, and price in structure exploration. The accuracy and pace of efficiency estimation broadly varies from one simulator to a different, relying on the underlying modeling particulars (e.g., cyclecorrect vs. MLbased mostly proxy fashions). Whereas analytical or ML-based proxy fashions are nimble by advantage of discarding low-level particulars, they typically undergo from excessive prediction error. Additionally, as a consequence of business licensing, there might be strict limits on the variety of runs collected from a simulator. General, these constraints exhibit distinct efficiency vs. pattern effectivity trade-offs, affecting the selection of optimization algorithm for structure exploration.
    It’s difficult to delineate the right way to systematically evaluate the effectiveness of varied ML algorithms beneath these constraints.
  3. Lastly, the panorama of ML algorithms is quickly evolving and a few ML algorithms want information to be helpful. Moreover, rendering the end result of DSE into significant artifacts resembling datasets is important for drawing insights in regards to the design house.
    On this quickly evolving ecosystem, it’s consequential to make sure the right way to amortize the overhead of search algorithms for structure exploration. It isn’t obvious, nor systematically studied the right way to leverage exploration information whereas being agnostic to the underlying search algorithm.

ArchGym design

ArchGym addresses these challenges by offering a unified framework for evaluating completely different ML-based search algorithms pretty. It includes two primary parts: 1) the ArchGym setting and a pair of) the ArchGym agent. The setting is an encapsulation of the structure price mannequin — which incorporates latency, throughput, space, power, and so on., to find out the computational price of operating the workload, given a set of architectural parameters — paired with the goal workload(s). The agent is an encapsulation of the ML algorithm used for the search and consists of hyperparameters and a guiding coverage. The hyperparameters are intrinsic to the algorithm for which the mannequin is to be optimized and may considerably affect efficiency. The coverage, alternatively, determines how the agent selects a parameter iteratively to optimize the goal goal.

Notably, ArchGym additionally features a standardized interface that connects these two parts, whereas additionally saving the exploration information because the ArchGym Dataset. At its core, the interface entails three primary indicators: {hardware} state, {hardware} parameters, and metrics. These indicators are the naked minimal to determine a significant communication channel between the setting and the agent. Utilizing these indicators, the agent observes the state of the {hardware} and suggests a set of {hardware} parameters to iteratively optimize a (user-defined) reward. The reward is a perform of {hardware} efficiency metrics, resembling efficiency, power consumption, and so on. 

ArchGym includes two primary parts: the ArchGym setting and the ArchGym agent. The ArchGym setting encapsulates the fee mannequin and the agent is an abstraction of a coverage and hyperparameters. With a standardized interface that connects these two parts, ArchGym offers a unified framework for evaluating completely different ML-based search algorithms pretty whereas additionally saving the exploration information because the ArchGym Dataset.

ML algorithms could possibly be equally favorable to satisfy user-defined goal specs

Utilizing ArchGym, we empirically reveal that throughout completely different optimization goals and DSE issues, a minimum of one set of hyperparameters exists that leads to the identical {hardware} efficiency as different ML algorithms. A poorly chosen (random choice) hyperparameter for the ML algorithm or its baseline can result in a deceptive conclusion {that a} explicit household of ML algorithms is best than one other. We present that with ample hyperparameter tuning, completely different search algorithms, even random stroll (RW), are in a position to establish the very best reward. Nevertheless, word that discovering the best set of hyperparameters might require exhaustive search and even luck to make it aggressive.

With a ample variety of samples, there exists a minimum of one set of hyperparameters that leads to the identical efficiency throughout a variety of search algorithms. Right here the dashed line represents the utmost normalized reward. Cloud-1, cloud-2, stream, and random point out 4 completely different reminiscence traces for DRAMSys (DRAM subsystem design house exploration framework).

Dataset building and high-fidelity proxy mannequin coaching

Making a unified interface utilizing ArchGym additionally allows the creation of datasets that can be utilized to design higher data-driven ML-based proxy structure price fashions to enhance the pace of structure simulation. To guage the advantages of datasets in constructing an ML mannequin to approximate structure price, we leverage ArchGym’s skill to log the information from every run from DRAMSys to create 4 dataset variants, every with a special variety of information factors. For every variant, we create two classes: (a) Various Dataset, which represents the information collected from completely different brokers (ACO, GA, RW, and BO), and (b) ACO solely, which reveals the information collected completely from the ACO agent, each of that are launched together with ArchGym. We prepare a proxy mannequin on every dataset utilizing random forest regression with the target to foretell the latency of designs for a DRAM simulator. Our outcomes present that:

  1. As we improve the dataset measurement, the typical normalized root imply squared error (RMSE) barely decreases.
  2. Nevertheless, as we introduce range within the dataset (e.g., accumulating information from completely different brokers), we observe 9× to 42× decrease RMSE throughout completely different dataset sizes.

Various dataset assortment throughout completely different brokers utilizing ArchGym interface.
The influence of a various dataset and dataset measurement on the normalized RMSE.

The necessity for a community-driven ecosystem for ML-assisted structure analysis

Whereas, ArchGym is an preliminary effort in the direction of creating an open-source ecosystem that (1) connects a broad vary of search algorithms to pc structure simulators in an unified and easy-to-extend method, (2) facilitates analysis in ML-assisted pc structure, and (3) kinds the scaffold to develop reproducible baselines, there are numerous open challenges that want community-wide help. Beneath we define a few of the open challenges in ML-assisted structure design. Addressing these challenges requires a nicely coordinated effort and a group pushed ecosystem.

Key challenges in ML-assisted structure design.

We name this ecosystem Structure 2.0. We define the important thing challenges and a imaginative and prescient for constructing an inclusive ecosystem of interdisciplinary researchers to sort out the long-standing open issues in making use of ML for pc structure analysis. If you’re all in favour of serving to form this ecosystem, please fill out the curiosity survey.

Conclusion

ArchGym is an open supply gymnasium for ML structure DSE and allows an standardized interface that may be readily prolonged to go well with completely different use instances. Moreover, ArchGym allows truthful and reproducible comparability between completely different ML algorithms and helps to determine stronger baselines for pc structure analysis issues.

We invite the pc structure group in addition to the ML group to actively take part within the growth of ArchGym. We consider that the creation of a gymnasium-type setting for pc structure analysis could be a major step ahead within the subject and supply a platform for researchers to make use of ML to speed up analysis and result in new and revolutionary designs.

Acknowledgements

This blogpost relies on joint work with a number of co-authors at Google and Harvard College. We want to acknowledge and spotlight Srivatsan Krishnan (Harvard) who contributed a number of concepts to this mission in collaboration with Shvetank Prakash (Harvard), Jason Jabbour (Harvard), Ikechukwu Uchendu (Harvard), Susobhan Ghosh (Harvard), Behzad Boroujerdian (Harvard), Daniel Richins (Harvard), Devashree Tripathy (Harvard), and Thierry Thambe (Harvard).  As well as, we might additionally wish to thank James Laudon, Douglas Eck, Cliff Younger, and Aleksandra Faust for his or her help, suggestions, and motivation for this work. We might additionally wish to thank John Guilyard for the animated determine used on this publish. Amir Yazdanbakhsh is now a Analysis Scientist at Google DeepMind and Vijay Janapa Reddi is an Affiliate Professor at Harvard.

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