>>> But note that "it isn't difficult to abstractly imagine machines and
>>> implementation code that could exploit this requirement" isn't the same
>>> as actually describing a sketch of such an implementation. If it isn't
>>> difficult, I'd like to see one.

>> The examples were probably some of the current implementations.  I
>> don't think anyone wanted to admit on record that their implementation
>> would suck unless spurious wakeups were allowed.  I think people
>> were smiling a lot when they spoke that particular statement.  A possible
>> implementation might be the syscall not keeping enough state information
>> to make it restartable after an EINTR.  This is not the case
>> for Linux which has enough information in the condvar and in the futex
>> to make futex syscalls restartable on EINTR if they wanted to.

> So,
> - wait on futex returns EINTR on signal
> - cond_wait implementation immediately returns on EINTR

> Well, that's a reason. However, there are still two questions:

> - why wait of futex returns on signals?