Contention among tasks concurrently running in a multicore has been deeply studied in the literature specially for on-chip buses. Most of the works so far focus on deriving exact upper-bounds to the longest delay it takes a bus request to be serviced (ubd), when its access is arbitrated using a time-predictable policy such as round-robin. Deriving ubd for a bus can be done accurately when enough timing information is available, which is not often the case for commercial-of-the-shelf (COTS) processors. Hence, ubd is approximated (ubdm) by directly experimenting on the target processor, i.e by measurements. However, using ubdm makes the timing analysis technique to resort on the accuracy of ubdm to derive trustworthy worst-case execution time estimates. Therefore, accurately estimating ubd by means of ubdm is of paramount importance. In this paper, we propose a systematic measurement-based methodology to accurately approximate ubd without knowing the bus latency or any other latency information, being only required that the underlying bus policy is round-robin. Our experimental results prove the robustness of the proposed methodology by testing it on different bus and processor setups.

Increasing confidence on measurement-based contention bounds for real-time round-robin buses

VARDANEGA, TULLIO
Supervision
;
2015

Abstract

Contention among tasks concurrently running in a multicore has been deeply studied in the literature specially for on-chip buses. Most of the works so far focus on deriving exact upper-bounds to the longest delay it takes a bus request to be serviced (ubd), when its access is arbitrated using a time-predictable policy such as round-robin. Deriving ubd for a bus can be done accurately when enough timing information is available, which is not often the case for commercial-of-the-shelf (COTS) processors. Hence, ubd is approximated (ubdm) by directly experimenting on the target processor, i.e by measurements. However, using ubdm makes the timing analysis technique to resort on the accuracy of ubdm to derive trustworthy worst-case execution time estimates. Therefore, accurately estimating ubd by means of ubdm is of paramount importance. In this paper, we propose a systematic measurement-based methodology to accurately approximate ubd without knowing the bus latency or any other latency information, being only required that the underlying bus policy is round-robin. Our experimental results prove the robustness of the proposed methodology by testing it on different bus and processor setups.
2015
Proceedings - Design Automation Conference
52nd ACM/EDAC/IEEE Design Automation Conference, DAC 2015
9781450335201
9781450335201
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3200422
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