Just tested latency from Java on my Corei5 2.8GHz, only single byte send/received, 2 Java processes just spawned, without assigning specific CPU cores with taskset:
TCP - 25 microseconds
Named pipes - 15 microseconds
Now explicitly specifying core masks, like taskset 1 java Srv or taskset 2 java Cli:
TCP, same cores: 30 microseconds
TCP, explicit different cores: 22 microseconds
Named pipes, same core: 4-5 microseconds !!!!
Named pipes, taskset different cores: 7-8 microseconds !!!!
so
TCP overhead is visible
scheduling overhead (or core caches?) is also the culprit
At the same time Thread.sleep(0) (which as strace shows causes a single sched_yield() Linux kernel call to be executed) takes 0.3 microsecond - so named pipes scheduled to single core still have much overhead
Some shared memory measurement: September 14, 2009 – Solace Systems announced today that its Unified Messaging Platform API can achieve an average latency of less than 700 nanoseconds using a shared memory transport. http://solacesystems.com/news/fastest-ipc-messaging/
Andriy
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