Chris Caudle wrote: > On Wed, April 6, 2016 2:49 am, Filipe Coelho wrote: > > If you have jack clients or plugins that heavily rely on mutexes, > > semaphores, conditions, etc the same thing might happen. > > That would be a buggy plugin design. > Seems it could be interesting to automate checking for some of that. I > thought maybe nm could help. Very much so. There's a large spread of software in linux audio which isn't realtime safe and correcting these issues is slow work. Half of the battle IMO is the spreading the information about what realtime safety is, why it is important, and how it should be achieved. > So is it possibly feasible to automate checking for non-realtime safe > function use in plugin binaries? I'm pretty confident it would not be > difficult to do with source, especially if you took the manual path of > finding the processing function by inspecting the code. In the case of C code it usually isn't too bad, but for C++ code it is still a very non-trivial task to perform the analysis even with the source available. As part of trying to correct these long standing issues within ZynAddSubFX one of the tools that I wrote starting back in 2012 was stoat: https://github.com/fundamental/stoat This tool uses llvm/clang to consume the source code and then construct the possible call graphs (missing only function pointers which are nearly possible to statically analyse). Using a combination of blacklists and whitelists you can say what functions/methods *should* be realtime safe and which ones are not safe. Based upon this information stoat identifies when a supposedly realtime safe function could call an unsafe function. This approach eliminates identifying calls to graphics libraries and threading locks which are never involved in the jack process callback. To clarify one other point in this thread, zyn is not absolutely 100% realtime safe and stoat can certainly point out the few remaining issues (there is a single location for memory allocation/deallocation which needs to be corrected (NO LOCKS)). Compared to yoshimi however it is an absolutely night and day difference. Based upon checking yoshimi's git again it should be essentially equal to the realtime safety that zyn had back at its 2.4.4 release: (unsafe function call graph) http://fundamental-code.com/2.4.4-realtime-issues.png Compare that to what was achieved for the 2.5.0 release of zyn: http://fundamental-code.com/2.5.0-realtime-issues.png Around 80% of those issues have been resolved within zyn since then. A similar analysis could be done easily on yoshimi following the instructions in stoat's README if someone is interested. --Mark McCurry (I just subbed for this, so hopefully I haven't messed up the threading)
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