Real. Time < Linux. SAM < TWiki Introduction. This page aims at presenting the two most important real- time Linux solutions, their setup and the expected performances on AT9. SAM So. Cs. The study covers the following two real- time Linux solutions. Global setup The board used are the AT9. SAM9. G2. 0EK, AT9. This is most commonly achieved by applying a patch set known as PREEMPT. Interrupt performance on linux kernel with RT patches - should be better? SAM9. M1. 0- G4. 5- EK and AT9. SAM9. 26. 3- EK. The following programs are used to stress the system. Ethernet interface and generate a lot of interrupts. Here is the script used to create load (doload. The drawback in theses cases is that the developpment is more difficult and the code have a restraint accces to kernel or userspace facilities. There are no special APIs, no special library.
What is a real-time system? Revision History Revision 0.1 2006-12-07 First release Revision 0.2 2006-12-13 CONFIG Meanwhile there's an rt17 patch set (https://www.kernel.org/pub/linux/kernel/projects/rt/3.8/). Did anybody give this a try? Does it work with the BBB? Realtime Preemption is (as of this writing 12/21/2004) a patch which tries to improve realtime performance of the Linux kernel. I've designed this and. For example, 2. 6. Connecting to www. OK. Length: 2. 52. K) . Lower latencies can be achieved by handling directly the event inside the kernel, but implementing application- specific code within the kernel is usually much more difficult. What is measured here is the full scheduling latency plus the time spent in the task to set the GPO including the switch in kernel space. The RT patch takes advantage of the fact that interrupt handlers run. Config: add rt Signed-off-by: Robert Nelson <[email protected]> Loading branch information. For AT9. 1SAM9. M1. G4. 5- EK and AT9. SAM9. G2. 0EK boards, GPIOs from the ISI connector are used: PB2. PB1. 0 is used as output. Both signals are connected to an oscilloscope which is setup in overlay mode in order to get the worst latency between input and output. The oscilloscope triggers on high to low transition on PB2. The output signal fill this 3. So we can only conclude that maximum latency is at least 3. The output signal fill this 3. So we can only conclude that maximum latency is at least 3. Those drivers cannot benefit from the existing hardware support in Linux, and must be rewritten independently. In the following examples, CFLAGS and LDFLAGS are set with march=armv. Linaro which will compile by default for armv. AT9. 1SAM family are amrv. CFLAGS=. This scripts need to know where the libraries and the headers have been installed. DESTDIR must be set to point to the staging root file system. DESTDIR=/home/gclement/rootfs/. It comes in 3 flavors: User task: periodic user- mode task. As for timer latency benchmark done on with cyclictest, what is measured here is the full scheduling latency plus the short time spent in the task to read the current time. Kernel Task: in- kernel periodic task. What is measured here is the full scheduling latency plus the short time spent in the task to read the current time, but here the task is in the kernel space so there is no context switch between kernel and user space. Timer IRQ: in- kernel timer handle. What is measured here is only the interrupt latency and the time spent in the interrupt handlers. It has been tested on 3 boards, with default configuration plus the following ones: CONFIG.
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