For jobs with that do very little work, the jobsystem can introduce
a lot of overhead, we mitigate this by:
- don't wake-up worker threads when scheduling several very small jobs,
like when scheduling the per-face jobs.
- don't wait for per-face jobs to finish -- we only did that to avoid
a copy of the job's data.
- don't use multi-threading at all if the job has too little work. We
evaluate the work using the scanline length and number of samples.
Even when hex modifier is used, 'char' should be printed as characters,
this is particularly relevant with 0.
e.g. out << (char)0, should write a nul terminator, not "0".
Instead of passing SamplerInterfaceBlocks and a SamplerBindingMap to
Program, we now set a 'sampler group' per binding point:
Program::addSamplerGroup(...)
A sampler group here consists of a list of N 'Sampler' and a 'Sampler'
is just a unique name (unifrom name in the shader) and binding point in
the shader.
That's all the driver layer needs.
With this change we get rid of the code that re-created the uniform
names in the driver -- this should never have been done there. And we
also remove the hash-map lookups in vulkan and metal drivers.
Program::shader() was taking a string before which didn't make sense
for spirv. Now it's just a blob, in the case of GL/Metal, the blob
must be a null terminated c-string, and the size must include the
terminating null character.
This fixes an out-of-bound access in ShaderBuilder::getShader() (which
doesn't exist anymore), because it was creating a CString passing
a size that included the null terminating char, which is not was CString
expects. CString can now assert() in that case.
driver::Program now uses a std::vector<> for storage, which we should
fix at some point (b/c it's a public header). CString was not suited to
store binary blobs.
This reverts a JobSystem optimization that attempted to avoid signaling
a condition when there was no waiters. Unfortunately, there was a
race that caused the the signaling thread to miss that the waiter flag
was set, thus not signaling.
- only signal waitAndRelease() when the corresponding job finishes and
only if there is waitAndRelease() active -- instead of signaling
every time a job ends.
- don't surrender time slice when attempting to steal a job and it fails
as long as some queue has jobs.
- check that we have to wait, because taking the lock
- add a benchmark
This change more than doubles the amount of jobs we can handle per
second (~965,000 jobs/s on Pixel3)
JobSystem::waitAndRelease used to spin to wait for the job to finish,
usually this wasn't a problem because the spinning thread was
able to handle other jobs. However, in cases where no job was
available it would actually spin in burn cpu cycles.
we now use a (separate) condition variable to handle that case.
We simply don't emit unwind tables, which are not needed anyways since
we're compiling without exceptions. the combined saving for all four
targets we support is about 120K.
This seems to improve .aar's compression, for a total gain of 152 KiB.
We also disable stack-protector in the jni code, since it wasn't
enabled in libfilament.a anyways. However, we now compile all debug
builds with -fstack-protector
- make Profiler::readCounters() not inline as it didn't need to be,
it's not performance critical and it's sufficiently large.
- don't inline hasExtensions(), same reason.
We used to only wake up a job-queue if there was already some jobs
running, the idea was that the current thread would handle the new job
as soon as calling wait(). However, there is no guarantee that wait()
will be called anytime soon.
cv.signal() is not very expensive on Android/Linux, as we're using
a custom implementation.
We're using timed condition variable in one place, but the STL version
pulls in a lot of code because it does clock calculations in
"long double" (!!!!). Since we already had an implementation
of condition_variable, we just add the timed version.
This saves several KiB of code.
Also don't use unique_lock() lock/unlock because it can throw exceptions.
* Clean-up EntityManager a bit
- use tsl::robin_set instead of std::set (which should have been unordered::set
anyways).
- getListeners() now returns a vector which avoids to traverse a set twice.
Turns out that copying the set wasn't as efficient as I thought.
* Improve jobsystem a bit
We recently added a job reference counting mechanism, but we were a bit
too aggressive about taking/release references.
Also make the API more complete by adding explicit retain/release,
which is needed to allow several threads to wait on the same job.
Also improve futex code by inlining it.
* Minor clean-ups
- fix a couple usage of std::function
- fix a couple usage of std::string
- remove ALIGN_LOOP, which didn't work
- fix a couple explicit/noexcept
- virtual -> override
* Fix spelling typos and other minor clang-tidy
* Fix a reuse after free in the job system
Jobs were destroyed and recycled while still in use
by wait() or run(). To fix this we introduce reference-counting of
jobs.
Jobs start with a ref-count of 1, which is decremented when a job
naturally finishes. Additionally, all user-facing methods acquire
a reference for the duration of the call.
* Fix an API inconsistency with JobSystem
JobSystem's API lets the user create jobs but not destroy them.
Jobs are destroyed automatically, without a way for the caller to
know when that happens.
We now explicitly enforce that jobs are no longer valid when
wait() returns. Multiple concurrent wait() are allowed however.
This is enforced by clearing the job pointer upon returning
from JobSystem::wait(Job* job).
* Rename linked-list put/get to push/pop
* Better fix for Job use after free
There was still a race condition where a run()'ed
job could be destroyed before wait() was called,
wait would then use a destroyed object.
The available APIs now are:
run() - runs and destroys a job
runAndWait() - run, then waits for and destroys a job
runAndRetain() - runs and keep a reference to the job
wait() - waits and destroys a job
wait() can only be used with a job obtained with runAndRetain().
* Get rid of unused code
This version of parallel_for has use-after-free issues anyways,
since we changed the semantics of run/wait/etc...
* Fix decRef() memory order
decRef() must ensure that all access to the
object have happened before destroying it.
* Fix memory order in atomic linked list's pop()
It needs acquire semantic, since we want to make
sure that no read/write are reordered before the
pop() -- which returns an object to the caller.
* Fix memory order on runningJobCount
we needed acquire semantic when about to destroy
the last job -- it's similar to decRef.
* Comment usages of std::memory_order_*
* Fix AtomicFreeList A-B-A bug
Turns out AtomicFreeList was not immune to the ABA bug. W're fixing
it here by using a 64-bits CAS, which is available on aarch64 and armv7.
This does not add any build stuff or new sample code yet, it just does
some prep to our C++ codebase:
- Similar to Android, WebAssembly will not be using BlueGL. We were
using a mixture of #if and #ifdef when checking for the existence of
certain GL prototypes, but the latter is what we want in order to
build robustly with any GL headers. (We still perform run-time checks
for extensions, this doesn't change that.)
- Add a trivial ContextManager, does a bit more than Dummy since it
needs to create an actual driver. This doesn't get compiled yet, it
just adds files to the tree.
- WebAssembly does not support mmap, execinfo, or asm volatile.
* Add single-threaded config to Filament.
This adds a tick method to Engine and disables a couple components
in Renderer (FrameSkipper and FrameInfoManager).
This will make it easier to support WebGL, and will allow us to remove
some of the command buffer debugging stuff that we added for Vulkan.
* tick => execute, and other review feedback
* Restore the ASSERT for FFence::wait.
* Try to clean up asset folders for sample apps.
This removes the build step where we copy a subset of assets, and makes
it so that FilamentApp hands out a "root path" for assets. For now this
is determined based on the location of the executable. This allows
developers to launch samples from any CWD.
Closes#11
* Restore asset copy to build.
* JobSystem now automatically free Jobs
Until now Job allocation used a linear allocator
strategy which required to “reset” the JobSystem
periodically — typically once per frame in
filament.
This is no longer required. We use a pool allocator
now, which doesn’t add much overhead. It does
use a spin-lock for thread-safety though, since
we assume very little contention, this shouldn’t
be a problem.
* Thread Safe Object Pool Allocator
A lock-less, thread-safe object pool allocator,
now used for storing JobSystem’s jobs allocations.
This gets rid of the spin-lock introduced in the
previous cl.
