Speaker
Description
The resource landscape available to LHC experiments is evolving, driven by industry trends and funding-agencies policies, from traditional WLCG sites dominated by x86 CPU resources, towards larger consolidated facilities, with a growing fraction of supercomputing centers, and a rising degree of hardware heterogeneity. The CMS experiment, which has already demonstrated substantial throughput gains in its High-Level Trigger through the use of coprocessors, is now preparing to profit from these rapidly changing scenario by extending heterogeneous computing to its offline workflows.
To support this evolution, the CMS Computing Model, and in particular the Submission Infrastructure (SI) system, must be proactively adapted and exercised for a future in which GPUs and other co-processors play a central role. The SI is responsible for provisioning compute resources and matching them to data processing, simulation, and analysis tasks according to CMS priorities and policies. Ensuring the most effective use of heterogeneous resources therefore requires a number of enhancements of the current SI.
Ongoing efforts include extending the description of remote resources and job requirements via HTCondor classads to enable precise matchmaking in the context of heterogeneous hardware architechtures, as well as providing physicists with an accurate catalogue of available capabilities. Policies for acquiring and allocating heterogeneous compute slots, including opportunistic resources, must evolve to maximize their impact on CMS processing needs. The execution of selected benchmarks will allow the rating of individual devices, thus enabling a precise prediction of tasks execution time. In addition, the possibility of dynamically allocating a device to multiple payloads will result in a more efficient utilization. Other developments are being considered, namely on the configuration and execution of mixed CPU+GPU workflows, support for non-NVIDIA GPU architectures, and the access and use of heterogeneous slots at HPC facilities.
This contribution will present the current status of these activities, along with the following steps in SI towards fully supporting CMS offline computing on the future heterogeneous resource ecosystem.