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Monday, October 26 • 13:00 - 13:50
Solving the Twelve Year Old ftrace Time Stamp Puzzle - Steven Rostedt, VMware

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Since 2008, the ftrace ring buffer inside the Linux kernel has been used to debug numerous issues. With recording events within nanoseconds, it's streamlined processing that keeps overhead very low, hard to debug areas of Linux can easily be traced. It works in all sorts of context including non-maskable-interrupts (NMIs), that makes it an ideal debugging tool. With its incorporated timestamp counter, it can show how long functions last, or time the latency between events.

But this timestamp had a flaw for all these years; It would not give time deltas for events recorded in a context that interrupted the recording of another event on the buffer. This issue has now been solved.

This talk will go over why it was so difficult to solve the nested event timestamp issue, and then a step by step dive into its solution. If you like to geek-out over hard to solve problems, and then see how they are eventually solved, you will enjoy watching this talk.

Speakers
avatar for Steven Rostedt

Steven Rostedt

Open Source Engineer, VMWare, Inc.
Steven has been working on the Linux kernel since 1998 (started while working on his masters). He has been working on the Linux kernel professionally since 2001. Steven is one of the original developers of the PREEMPT_RT patch which turns Linux into a true real-time operating system... Read More →



Monday October 26, 2020 13:00 - 13:50 GMT
Linux Systems Theater
  Linux Systems