Intel processor trace – Observations from Uppsala

“Processor Performance Insights and Optimization” – Computer and System Architecture Unraveled Event Four

Finally, the fourth CaSA, Computer and System Architecture Unraveled, meetup happened on November 6. It took far too long to get it organized, but we finally did it. The theme was about processor performance analysis and efficient processor implementation, offering two talks from very different perspectives. The location was almost the same as before, on the 19^th floor of the Kista Science Tower building. Once more thanks to the sponsorship from Vasakronan and Kista Science City.

Microsoft REPT: You CAN Reverse from a Core Dump!

There are some things in computing that seem “obviously” true and that “clearly” make it “impossible” to do some things. One example of this is the idea that you cannot go backwards in time from the current state of a program or computer system and recover previous state by just reversing the semantics of the instructions in the program. In particular, that you cannot take a core dump from a failed system and reverse-execute back from it – how could you? In order to do reverse debugging and reverse execution, you “have to” record the state at the first point in time that you want to be able to go back to, and then record all changes to the state. Turns out I was wrong, as shown by a recent Usenix OSDI paper.