per-CPU counters and locking
Posted Feb 5, 2006 2:11 UTC (Sun) by man_ls
In reply to: per-CPU counters and locking
Parent article: The search for fast, scalable counters
how are you going to read the per-CPU counter of another CPU?
Never thought of that; just another example of why kernel programming sometimes looks so hard to outsiders.
The only way is for that CPU to write it out to main memory and for you to go to main memory to get it. That takes a long time, and that's the slowness that per-CPU counters are supposed to eliminate.
At least it would spare the "expensive locking operations" mentioned in the main article, wouldn't it?
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