Daniel Eischen wrote:
On Thu, 22 Oct 2009, Andrew Gallatin wrote:
Hi,
We're designing some software which has to lock access to
shared memory pages between several processes, and has to
run on Linux, Solaris, and FreeBSD. We were planning to
have the lock be a pthread_mutex_t residing in the
shared memory page. This works well on Linux and Solaris,
but FreeBSD (at least 7-stable) does not support
PTHREAD_PROCESS_SHARED mutexes.
We then moved on to posix semaphores. Using sem_wait/sem_post
with the sem_t residing in a shared page seems to work on
all 3 platforms. However, the FreeBSD (7-stable) man page
for sem_init(3) has this scary text regarding the pshared
value:
The sem_init() function initializes the unnamed semaphore pointed
to by
sem to have the value value. A non-zero value for pshared
specifies a
shared semaphore that can be used by multiple processes, which this
implementation is not capable of.
Is this text obsolete? Or is my test just "getting lucky"?
I think you're getting lucky.
Yes, after playing with the code some, I now see that. :(
Is there recommended way to do this?
I believe the only way to do this is with SYSV semaphores
(semop, semget, semctl). Unfortunately, these are not as
easy to use, IMHO.
Yes, they are pretty ugly, and we were hoping to avoid them.
Are there any plans to support either PTHREAD_PROCESS_SHARED
mutexes, or pshared posix semaphores in FreeBSD?
Thanks,
Drew
_______________________________________________
freebsd-hackers@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
