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c++sleeptransactional-memory

sleep without system or IO calls

I need a sleep that does not issue any system or IO calls for a scenario with Hardware Transactional Memory (these calls would lead to an abort). Sleeping for 1 microsecond as in usleep(1) would be just fine.

This question suggests to implement nested loops to keep the program busy and delay it for some time. However, I want to be able to compile with optimization which would delete these loops.

An idea could be to calculate some sophisticated math equation. Are there approaches to this? The actual time waited does not have to be precise - it should be vaguely the same for multiple runs however.

Solution

  • Try a nop loop with a volatile asm directive:

    for (int i = 0; i < 1000; i++) { 
    asm volatile ("nop"); 
}

    The volatile should prevent the optimizer from getting rid of it. If that doesn't do it, then try __volatile__.