Central processing.
WHAT IT DOES
Fetches instructions, decodes them, executes them, and stores results.
WHAT DETERMINES PERFORMANCE
- Clock speed: cycles per second
- Cores: independent execution units
- Cache: small fast memory holding recently used data
- Architecture: how efficiently work is done per cycle
WHY CLOCK SPEED ALONE MISLEADS
Two processors at the same speed can differ substantially in work performed.
WHAT CORES PROVIDE
The ability to execute several tasks genuinely simultaneously.
WHAT LIMITS THEIR BENEFIT
Software that cannot divide its work.
WHAT THAT MEANS
Some tasks are not faster on more cores at all.
WHAT CACHE DOES
Reduces waiting for memory, which is far slower than the processor.
WHY THERMAL MANAGEMENT MATTERS
Processors reduce speed when too hot, to protect themselves.
WHAT THAT PRODUCES
A machine that performs well briefly, then slows.
WHAT TO CHECK WHEN THAT SYMPTOM APPEARS
Cooling: dust, fans, thermal contact.
WHAT TO MONITOR
Temperature and utilisation, when diagnosing performance.
