..Instead of DEBUG so these work in debugoptimized builds.
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Acked-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17408>
This makes simple_mtx_destroy set the counter to an invalid canary
value and then makes lock/unlock assert that the value is legal.
That way, calling lock/unlock after destroy will assert fail,
rather than deadlocking or potentially even working.
This has caught real deadlocks in dEQP multithreaded tests (in st/mesa
shader variant zombie list handling), which have since been fixed.
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Suggested-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Decorate the parameters accordingly with "UNUSED" or "MAYBE_UNUSED" (for
the param that is used in debug mode, but not in release mode).
v2: move UNUSED decoration in front of parameter declaration
Signed-off-by: Gert Wollny <gw.fossdev@gmail.com>
Reviewed-by: Brian Paul <brianp@vmware.com> (v1)
While modern pthread mutexes are very fast, they still incur a call to an
external DSO and overhead of the generality and features of pthread mutexes.
Most mutexes in mesa only needs lock/unlock, and the idea here is that we can
inline the atomic operation and make the fast case just two intructions.
Mutexes are subtle and finicky to implement, so we carefully copy the
implementation from Ulrich Dreppers well-written and well-reviewed paper:
"Futexes Are Tricky"
http://www.akkadia.org/drepper/futex.pdf
We implement "mutex3", which gives us a mutex that has no syscalls on
uncontended lock or unlock. Further, the uncontended case boils down to a
cmpxchg and an untaken branch and the uncontended unlock is just a locked decr
and an untaken branch. We use __builtin_expect() to indicate that contention
is unlikely so that gcc will put the contention code out of the main code
flow.
A fast mutex only supports lock/unlock, can't be recursive or used with
condition variables. We keep the pthread mutex implementation around as
for the few places where we use condition variables or recursive locking.
For platforms or compilers where futex and atomics aren't available,
simple_mtx_t falls back to the pthread mutex.
The pthread mutex lock/unlock overhead shows up on benchmarks for CPU bound
applications. Most CPU bound cases are helped and some of our internal
bind_buffer_object heavy benchmarks gain up to 10%.
Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Alyssa Rosenzweig
Jesse Natalie
Rob Clark
Jan Beich
Marek Olšák
Eric Engestrom
Kenneth Graunke
Gert Wollny
Nicolai Hähnle
Timothy Arceri