Daniel Eischen wrote:
We already use umtx. This really is a hack and I wouldn't advocate it. I'm not sure how you could make it work and not break existing ability to return appropriate error codes without slowing down the path in the non-shared case. You'd have to check to see if the address space was shared or not, which would require a system call.
I'm probably missing something. What does it matter if the address space is shared, as long as the umtx struct is in shared memory? From my quick read, the umtx operations use a lock word in userspace. For uncontested locks, they use atomic ops to flip an id into the lock word. The kernel takes over for contested locks, and does sleeping, wakup, etc. Is this correct? Is there something here that matters if the address space (and not just the lock word) is shared?
All our public pthread_foo() symbols are weak. You can easily override them in your application code in the #ifdef freebsd case. What is wrong with providing your own library that overrides them to do what you require - this shouldn't change your application code?
For our code, I was thinking of something like: #ifdef FreeBSD #define lock(x) umtx_lock(x, getpid()) #define unlock(x) umtx_unlock(x, getpid()) #else #define lock(x) pthread_mutex_lock(x) #define unlock(x) pthread_mutex_lock(x) #endif I should probably just shut up and try it.. 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"
