I have successfully enabled SIO_LOOPBACK_FAST_PATH option on Windows 10 even though there isn't much information on whether Windows 10 supports it. Here is some info on the feature link1 link2
I have a basic TCP server and client using send()/recv() API that can be configured to use as many threads as I want.
Now here are the test results, I get the same ratios no matter how many threads I use for the test but to be clear I used 8 sending and 8 receiving threads for results below. Ran on an I7-4770K, with all tests consuming 100% CPU as reported by task manager.
HyperThreading Off (4 logical cores)
SIO_LOOPBACK_FAST_PATH enabled : 140K packets per second
SIO_LOOPBACK_FAST_PATH disabled: 210K packets per second
HyperThreading On (8 logical cores)
SIO_LOOPBACK_FAST_PATH enabled : 140K packets per second
SIO_LOOPBACK_FAST_PATH disabled: 80K packets per second
Why is this test with HyperThreading enabled slower than without it? And why does this test perform SLOWER when HyperThreading is disabled and the option is enabled. I am quite puzzled by the results as the option improves speed with HT on but not when HT is off, also puzzled by hyperthreading completely tanking the results.
