Lowest latency notification method between process under Linux

Question

I\'m looking for the lowest latency IPC that allow to put one process to sleep and allow other process to wake it.

I\'m looking for the lowest laten

Answer 1

Using the same code provided by @Artyom, but in a more morden hardware.

CPU: i9-9900k, closing C/S/P-state and set scaling policy as performance which keeps cores running at the maximum frequency(~5GHz).

OS: Preempt-RT patched Linux with kernel5.0.21, providing better real-time performance.

CPU affinity: two processes apartly running in two isolated cores, which keep away from irrelevant processes and interrupts AMSP.

Results:

Semaphore (sem_wait/sem_post - kernel - futex):

sleep us     mean             minimum  median      %99
       1     1.75 ±0.1          1.60     1.74     1.82
      10     1.76 ±0.0          1.61     1.75     1.83
     100     2.12 ±0.3          1.59     2.24     2.42
    1000     2.46 ±0.3          1.75     2.47     2.56
   10000     2.45 ±0.1          2.11     2.44     2.54

Signal (kill/sigwait)

sleep us     mean            minimum   median      %99
       1     2.15 ±0.2          2.00     2.13     2.22
      10     2.12 ±0.2          1.93     2.11     2.19
     100     2.56 ±0.3          2.00     2.67     2.88
    1000     2.90 ±0.3          2.17     2.90     3.01
   10000     2.94 ±0.5          2.66     2.89     3.03

Pipe (pipe + write/read)

sleep us     mean            minimum   median      %99
       1     2.05 ±0.2          1.88     2.03     2.15
      10     2.06 ±0.3          1.89     2.04     2.17
     100     2.54 ±0.4          1.88     2.63     2.87
    1000     2.98 ±0.3          2.27     2.98     3.09
   10000     2.98 ±0.3          2.69     2.96     3.07

Socket (socketpair +write/read)

sleep us     mean            minimum   median      %99
       1     3.11 ±0.4          2.85     3.09     3.22
      10     3.14 ±0.1          2.92     3.14     3.25
     100     3.66 ±0.5          2.92     3.74     4.01
    1000     4.03 ±0.4          3.28     4.03     4.17
   10000     3.99 ±0.4          3.64     3.96     4.10

As a reference busy waiting:

sleep us     mean            minimum   median      %99
       1     0.07 ±0.1          0.06     0.07     0.07
      10     0.07 ±0.1          0.06     0.07     0.07
     100     0.07 ±0.0          0.06     0.07     0.08
    1000     0.09 ±0.1          0.07     0.08     0.09
   10000     0.09 ±0.1          0.07     0.09     0.09