4 ms·
How does that compare to undo.io ?
by entelechy 8y ago
How does that compare to undo.io ?
- roca 8y agorr has a similar feature set to UndoDB. rr is probably a bit more efficient during recording. However, UndoDB doesn't depend on the performance counters the way rr does, so it works in situations where those counters are unavailable (e.g. some VM guests). Also UndoDB works on ARM, but due to the way ARM implements atomics (see above) rr's approach can't work on ARM. (Until/unless we get ARM to add support for trapping on failed LL/SC.)
- andrey_utkin 8y agoUndo has some features rr doesn't have. It supports shared memory operations. It works in virtual machines and "in cloud". It imposes less strict requirements on kernel or CPU features, for example, it works on AMD. Fundamentally, what differs UndoDB and Undo Live Recorder from rr is the architecture based on machine code instrumentation.
- MarkUndo 8y agoActually, I think rr supports shared memory operations under some circumstances... (I'd love to have my beliefs confirmed / corrected by somebody more knowledgeable) My understanding is that rr has some handling for read-only shared memory and for arbitrary sharing within a tree of recorded processes. Undo's shared memory is different because it doesn't need the other process to be recorded, so you can do read/write sharing with arbitrary processes or devices. (disclaimer: current Undo engineer)
- roca 8y agoYou're correct.