The ORCs are coming

Posted Jul 20, 2017 19:57 UTC (Thu) by corbet (editor, #1)
In reply to: The ORCs are coming by jhoblitt
Parent article: The ORCs are coming

ORC will track neither of those things; it just provides the information needed to make sense of the kernel stack. The kallsyms mechanism can associate symbols with addresses, as always.

The ORCs are coming

Posted Jul 20, 2017 20:58 UTC (Thu) by Sesse (subscriber, #53779) [Link] (2 responses)

A related question; will this eventually seep down into userspace, so that we can get reliable perf backtraces without frame pointers? (Yes, there's --call-graph=dwarf, but it requires dumping the entire stack to the perf trace, since DWARF is too slow to trace in realtime. So it makes for slow, huge traces.)

User space

Posted Jul 20, 2017 21:06 UTC (Thu) by corbet (editor, #1) [Link] (1 responses)

That's a question that came up in the conversation; I didn't manage to work it into the article, sorry. There is definitely interest in doing that, and it seems possible, but nobody is working on it at the moment.

User space

Posted Jul 22, 2017 2:02 UTC (Sat) by alkbyby (subscriber, #61687) [Link]

User space is likely to need more complex unwinding support. Since it has wider set of possible compilers/runtimes and programming language features. I.e. at least unwinding RBP is likely to be needed.