3. Agenda
What's real-time in this context?
Why is real-time still a concern?
Ways to deal with the problem
• Off to secondary hardware
• Hypervisor or AMP
• PREEMPT_RT
• CPU isolation and dynamic tick
Future?
4. Realtime
Real-time can mean a lot of different
things to different audiences
• Low maximum latency: below 100 us,
sometimes down to 20us
• Very low risk of every breaking that
5. Why is this a concern
2013?
• Plain Linux wasn't designed to deal with low latency
• A move towards "commodity" hardware - less
special stuff means solving the problems in general
CPUs
• Linux everywhere: RTOS-solutions get moved over
from legacy systems to Linux-based
• Still a lot of stacks and applications that act in CPU
but needs to respond fast and accurately
• Sometimes a bit more requested than perhaps can
be technically motivated
7. Separate dedicated HW
• A tested and proven way
• A separate small chip (with an
RTOS?) for just the time critical stuff
• ... or an FPGA
• But it adds system complexity and
price