Instant replay: Debugging C and C++ programs with rr

Re:Instant replay: Debugging C and C++ programs with rr by ncmncm on Tuesday May 04, 2021 @06:18PM (#27043568)

GDB is supposed to have reverse execution capability now. How does its facility compare to rr? Are they complementary, or one a pale shadow of the other, or something else?

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Re:Instant replay: Debugging C and C++ programs with rr by sanxiyn on Tuesday May 04, 2021 @09:04PM (#27044877)

rr is approximately infinitely faster than GDB reverse debugging. rr's innovation is low overhead reverse debugging.

rr's typical overhead is 20% -- 2x overhead is considered unacceptable for rr. You could reverse debug coreutils with GDB fine, but it won't work for Firefox. That's why rr was written.

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Re:Instant replay: Debugging C and C++ programs with rr by ncmncm on Tuesday May 04, 2021 @10:32PM (#27045519)

So, pale shadow. Thank you, this is what I needed to know. Time spent learning rr looks like a good investment.

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Re:Instant replay: Debugging C and C++ programs with rr by khuey on Tuesday May 04, 2021 @11:59PM (#27046037)

You shouldn't need to learn much. rr uses gdb's existing reverse-debugging UI commands, it just swaps out the backend implementation with a far more powerful version.

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