Hello Ricardo, On 04/18/2018 05:18 PM, Ricardo Biehl Pasquali wrote: > Perhaps the current definition of a semaphore in > sem_overview.7 could be clearer. > > A semaphore is an integer whose value is never allowed > to fall below zero. > > What about the definition from the book [1]_ in the > section (2.2.5 Semaphores)? > > [...] an integer variable to count the number of wakeups > saved for future use. > > It is simple enough to be easy to understand. Kind of > self-explanatory. > > Also, the whole "semaphore description" paragraph could be > rewritten. A proposal as an example: > > Semaphore is a counter of its pending wakeups. A call to > sem_wait() consumes one wakeup (decrements counter). If > there is no wakeup to be consumed (counter equals zero) > sem_wait() blocks. sem_post() adds one wakeup (increments > counter). > > or something like: > > A semaphore is represented by an integer that stores the > number of semaphore's pending wakeups (i.e., the number > of calls to sem_wait() that won't block). [...] > > Maybe I'm talking bullshit, but at least it's worth to > check it out. FWIW, I find the above less clear than the existing text. But, I did write that text. I'm open to more opinions on the subject, but I'm not (so far) inclined to change the text. Cheers, Michael > .. [1] Operating systems: design and implementation; 1997; > Andrew S. Tanenbaum, Albert S. Woodhull; 2nd ed. > > Cheers! > > pasquali > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
