"the cost of embedded measurement was MINUS 10 percent or better - because the knowledge that had been gained from the performance instrumentation had made the application at the very least 10% faster than it would have been without the instrumentation in place"
"The knee in response times is important on a system with random arrivals because these tend to cluster and cause temporary spikes in utilization. These spikes need enough spare capacity to consume so that users don't have to endure noticeable queuing delays. For example, the spare capacity needed to handle request clusters on a 1-core system is at least 50% CPU utilisation; 2-core is at least 43%; 4-core - 34%; 8-core 26%; 32-core - 14%; 64-core - 11%; 128-core - 8%."