Title: RT troubles, lessons learned, and open questions

Saturday, October 21, 2017 • 9:20 - 10:10

Over the years of using PREEMPT_RT, at National Instruments, we have managed to run into some of its trouble spots. This presentation will summarize some of our woes, lessons learned and open up a discussion about possible solutions.

Possible topics for discussion:

• timer expirations coming from low priority threads can introduce large latencies for RT threads waiting on a timer expiration;
• stalls when doing multiple PCI/PCIe MMIO writes followed by a read;
• migration events can stack up to large latencies;
• CPU prefetching into memory regions mapped over slow buses can cause latency spikes.

RT users and developers.

Gratian has been playing around with Linux since 1999 among other embedded and real-time OSes. He is currently employed by National Instruments on the RT OS team, working almost exclusively with Linux and PREEMPT_RT.