1. A method comprising: to update contents of a section of memory, copying a global flip-counter bit to a local flip-counter bit, the global flip-counter bit specifying which of a first set of per-processor counters and a second set of per-processor counters is a current set of per-processor counters and which is a last set of per-processor counters, the global flip-counter-bit also specifying which of a first set of per-processor need-memory-barrier bits and a second set of per-processor need-memory-barrier bits is a current set of per-processor need-memory-barrier bits and which is a last set of per-processor need-memory-barrier bits; where attempting to acquire a flip-counter-bit lock on the global-flip-counter bit is successful, where the global flip-counter bit has not changed while acquiring the flip-counter-bit lock, where all of the last set of per-processor need-memory-barrier bits are equal to a first predetermined value, and where a sum of all of the last set of per-processor counters is equal to a second predetermined value, incrementing each of the last set of per-processor need-memory-barrier bits, using the local flip-counter bit; sending an inter-processor interrupt to execute a memory barrier if needed; where all of the last set of per-processor need-memory-barrier bits are equal to a second predetermined value, setting each of the current set of per-processor need-memory-barrier bits to zero, using the local flip-counter bit, inverting the global flip-counter bit; and, releasing the flip-counter-bit lock.