CAP-OS: Operating system for runtime scheduling, task mapping and resource management on reconfigurable multiprocessor architectures

Abstract

Operating systems traditionally handle the task scheduling of one or more application instances on a processor like hardware architecture. Novel runtime adaptive hardware exploits the dynamic reconfiguration on FPGAs, where hardware blocks are generated, started and terminated. This is similar to software tasks in well established operating system approaches. The hardware counterparts to the software tasks have to be transferred to the reconfigurable hardware via a configuration access port. This port enables the allocation of hardware blocks on the FPGA. Current reconfigurable hardware, like e.g. Xilinx Virtex 5 provide two internal configuration access ports (ICAPs), where only one of these ports can be accessed at one point of time. In e.g. a multiprocessor system on an FPGA, it can happen that multiple instances try to access these ports simultaneously. To prevent conflicts, the access to these ports as well as the hardware resource management needs to be controlled by a special purpose operating system running on an embedded processor. This special purpose operating system, called CAPOS (Configuration Access Port-Operating System), which will be presented in this paper, supports the clients using the configuration port with the service of priority-based access scheduling, hardware task mapping and resource management

Rainbow: An Operating System for Software-Hardware Multitasking on Dynamically Partially Reconfigurable FPGAs

“…Several works were devoted to scheduling and placement of HW tasks (or reconfigurable hardware accelerators) on the FPGA [25][26][27][28][29][30][31]. In [25], an online scheduling and placement algorithm targeting 1D and 2D model of reconfigurable area is presented.…”

“…Similarly to work presented in [26]. Configuration Access Port OS (CAP-OS) [31] shows a mixed offline/online scheduling strategy utilizing information extracted from the CDFGs and is implemented on Xilkernel OS [33] running on a microprocessor. In the approaches presented in [26,27,31], HW tasks comprising the CDFGs execute in a nonpreemptive manner till their completion.…”

“…Configuration Access Port OS (CAP-OS) [31] shows a mixed offline/online scheduling strategy utilizing information extracted from the CDFGs and is implemented on Xilkernel OS [33] running on a microprocessor. In the approaches presented in [26,27,31], HW tasks comprising the CDFGs execute in a nonpreemptive manner till their completion. Work in [32] presents a non-preemptive scheduling strategy where HW tasks may voluntarily relinquish the allocated resources at certain points of their execution.…”

“…The work does not consider data dependencies between HW tasks. The works in [28,29] and CAP-OS [31] do not support preemption of the HW tasks' execution but allow for termination of their reconfigurations.…”

“…Similarly to works presented in [26][27][28][29][30]32], it targets systems where the reconfigurable area is divided into fixed regions. Unlike the works in [28,29,31], this work allows for true preemption of the HW task's execution phase. The concept of reservation of reconfigurable resources has been already introduced in [29,30].…”