On 10/18/2017 10:10 AM, Michael Kerrisk (man-pages) wrote:
DESCRIPTION
The pthread_spin_init() function allocates any resources required
for the use of the spin lock referred to by lock and initializes
the lock to be in the unlocked state. The pshared argument must
have one of the following values:
I think somewhere this should say that it is not possible to change the
address of a spinlock after initialization (you can't memcpy it
somewhere else and expect that it will keep working). Other pthread
objects have the same problem, of course.
NOTES
Spin locks should be employed in conjunction with real-time sched‐
uling policies (SCHED_FIFO, or possibly SCHED_RR). Use of spin
locks with nondeterministic scheduling policies such as
SCHED_OTHER probably indicates a design mistake. The problem is
that if a thread operating under such a policy is scheduled off
the CPU while it holds a spin lock, then other threads will waste
time spinning on the lock until the lock holder is once more
rescheduled and releases the lock.
Isn't the more important concern whether there are sufficient resources
to run all the threads that block on spinlocks?
Thanks,
Florian
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