2 docs tagged with "itm"

There is a category of bug that a breakpoint destroys by looking at it, and a log line destroys almost as thoroughly. A race between two interrupts, an occasional priority inversion, a state machine that takes a wrong branch once in ten thousand iterations — halting the core to inspect any of these changes exactly the timing that produced them, and a printf line inserted to catch them costs enough cycles to close the window it was supposed to observe. The Debug Toolbox's perturbation table already ranks every instrument in this folder by how much it disturbs the thing it is measuring; trace is the answer at the bottom of that table, the one built specifically to be close to zero.

Here is the observation this page exists to explain. You have a fault that happens once every few minutes — a corrupted buffer, a missed deadline, a state machine that ends up somewhere it cannot reach. You add a printf to narrow it down. The fault stops happening. You remove the printf and it comes back.