Comment heiesenberg doesn't apply here (Score 2) 81
maybe I'm just too tired right now, but I did not detect any heisenberg ref's in the threads I've read here on this topic. Trying to instrument a thread of execution is usually death for that thread. I despise the notion of "performance monitors". If you build it right, it will work, and any anomalies usually succumb to thoughtful analysis. Instrumenting a network at the level you guys are talking about can kill it, severely. Get ye a good sniffer, and learn to read it's utterances.
Intuitively it would seem that measuring threads in great detail would distort the measurement. However, performance registers on board CPUS (I'm thinking Intel at the moment) allow one to monitor certain aspects of threads with almost no overhead whatsoever. It's perfectly feasable and desirable to monitor code and a fine grained level.
There are many performance anomalies that can't necessarily be identified at the design level (for example pipeline flushing and cache problems). These detailed measurements can tell you much more about your program's behavior than the standard profiler can.
Intuitively it would seem that measuring threads in great detail would distort the measurement. However, performance registers on board CPUS (I'm thinking Intel at the moment) allow one to monitor certain aspects of threads with almost no overhead whatsoever. It's perfectly feasable and desirable to monitor code and a fine grained level.
There are many performance anomalies that can't necessarily be identified at the design level (for example pipeline flushing and cache problems). These detailed measurements can tell you much more about your program's behavior than the standard profiler can.
