RTKernel RISC Real-Time Scheduler
RTKernel RISC Real-Time Scheduler |
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RTKernel-RISCRTKernel-RISC is a powerful real-time multitasking scheduler for 32-bit x86 embedded systems. RTKernel RISC is compact (about 16k code, 6k data), fast, and offers excellent real-time response times. All RTKernel-RISC threads run within a single program (single process, multi-threaded). RTKernel-RISC ThreadsAn RTKernel-RISC thread is implemented as a C/C++ function. A program can dynamically create threads using the appropriate kernel API calls. These threads are subsequently executed in parallel with the main thread and any other threads. Each thread has its own stack, a priority between I and 64, and a task state. Several threads can be started executing the same code; however, each is allocated its own stack and thus its own local variables. All threads have access to the programís global data. Thus, shared code and shared data are inherently implemented by RTKernel-RISC. Inter-Task CommunicationRTKernel-RISC offers three different mechanisms for inter-task communication: Semaphores allow the exchange of signals for activating and suspending threads. RTKernel-RISC supports counting, binary, event, resource, and mutex semaphores. Resource and mutex semaphores implement priority inheritance. Mailboxes (also known as queues or FIFO buffers) allow threads to exchange messages asynchronously. The maximum number and size of messages can be configured for each mailbox. High priority messages can be sent to a mailbox ahead of all others. Mailboxes can also be used to send data from hardware interrupt handlers and threads. Message-passing is used for a synchronous exchange of messages. No data is buffered, data is sent directly from one thread to another. The SchedulerThe RTKernel-RISC scheduler is event-driven. It was developed specifically for real-time requirements and adheres to the following rules: Priority Scheduling:Of all threads in state Ready, the thread with the highest priority runs. Round-Robin:If the kernel must choose from several Ready threads with the same priority, the thread that hasnít run for the longest time is activated. Priority Ordered Queues:If several threads are waiting for an event, they are activated upon the occurrence of that event in sequence of their priorities. Deterministic Scheduling:With the exception of time-slice task switches, a task switch is only performed if rule 1 would be violated. The application can dynamically change thread priorities and it can turn preemptions and time-slicing on and off at run-time. InterruptsThe application's interrupt handlers can suspend or activate threads. Interrupt handlers can be programmed completely in C/C++ within the application They can freely exchange signals or data with threads using semaphores or mailboxes. Semaphore or mailbox operations may then initiate a task switch, if required. Interrupts from any hardware can be processed. DebuggingRTKernel-RISC is delivered in two versions. The Standard Version is optimized for minimum size and best performance, while the Debug Version contains additional code for parameter and consistency checks at run-time. The Debug Version recognizes
usage errors and issues
corresponding error messages. Moreover,
the Debug
Version offers numerous
debugging aids. For
example, the current
source code
position of
a thread can be displayed,
all locked resources
can be listed, or
the CPU time requirements
can be determined for each thread
and interrupt handler.
An especially powerful
tool is the Kernel Tracer;
it can log kernel and
application events
in real-time for
off-line
analysis. RTKernel-32 CompatibilityWith a few exceptions Rtkernel-RISC is compatible with RTKernel-32. RTKernel-32 is part of the RTOS-32 development suite for protected mode X86. RTOS-32 has a large installed base and worldwide reputation for rock solid value and reliability. Supplemental ModulesRTKernel-RISC is supplied with the following supplemental modules, always delivered in full source code:
Optional ModulesTightly integrated versions of the RTIP TCP-IP stack and ERTFS DOS compatible file system packages are available for RTKernel-RISC. PerformanceRTKernel RISC offers excellent performance. It comes with a benchmark program that may be used to measurei ts performance on any computer. The performance table gives some results for four typical X86 based target computers and for a 24 MHz MPC860 processor Support/CompatibilityRTOS, DRIVER and COMPILER
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