Partitioned Scheduling of Multimode Systems on Multiprocessor Platforms: when to do the Mode Transition? José Marinho, Gurulingesh Raravi, Vincent Nélis and Stefan Petters CISTER – ISEP Research Unit

Multi-mode systems Mode 1 Mode 2 MCR D transition time bound System is composed of set of modes Each mode is composed of a set of tasks with timing requirements Mode transition triggered by an MCR Mode transitions have to complete in a bounded time interval The length of this interval has to smaller than a given value (mode transition deadline) Mode 1 Mode 2 MCR Define MCR, tau 4 collour is messy. Be more explicit on what is a mode D transition time bound 02-12-2018 José Marinho

Partitioned Multi-mode Each processor treated as a bin For each mode a partitioning table exists Cores operate mode transitions independently Mode transition can be handled with single-core protocols straightforwardly Idle time protocol is still valid (simplest protocol) Π1 Π2 Mode 1 Π1 Π2 Mode 2 02-12-2018 Jose Marinho

Mode Independent tasks (MIT) A task may belong to more than one mode The temporal behaviour can not be perturbed by a mode change between two modes for which the task is common Task may be in the same partition across common modes Single-core protocols may be used Mode transitions core- independent Π1 Π2 Mode 1 MIT Π1 Π2 Define MIT in the text and refer it Mode 2 02-12-2018 Jose Marinho

Partitioned Multi-mode with MIT MIT task may not be in the same partition Only feasible partition assignment may lead to this Bin packing algorithm may blindly create the situation mode changes will require task migration Π1 Π2 τ5 U=0.1 τ2 U=0.46 τ3 U=0.4 Mode 1 τ1 U=0.51 τ4 U=0.5 Π1 Π2 τ3 U=0.4 τ2 U=0.46 Mode 2 τ4 U=0.5 τ6 U=0.6 02-12-2018 Jose Marinho

Transition Example Mention why this is different from single core 02-12-2018 Jose Marinho

Discussion Global scheduling during the mode transition is required when task migration exist Some Multi-mode task-sets with MIT may not need migrations at all Create a sufficient test to check if migrations are not needed Derive resource augmentation bound Bin packing procedure system-wide that ensures no task migration or minimizes migrations Remove unfeasible mode transitions 02-12-2018 Jose Marinho

Discussion Global scheduling during the mode transition is required when task migration exist Some Multi-mode task-sets with MIT may not need migrations at all Create a sufficient test to check if migrations are not needed Track the maximum admissible interference of MIT’s Derive resource augmentation bound Is task migration sufficient or would job migration be more efficient Bin packing procedure system-wide that ensures no task migration or minimizes migrations Remove unfeasible mode transitions 02-12-2018 Jose Marinho