On 2022-12-21 17:12, David Marchand wrote: > On Sun, Dec 18, 2022 at 11:01 AM Morten Brørup <m...@smartsharesystems.com> > wrote: >> >> This RFC introduces per-thread constructors/destructors: >> * Per-thread constructors are functions called as the first thing from newly >> created threads. This can be used to initialize variables in thread-local >> storage, variables depending on the (tid_t) thread id, and to call setup >> functions that must be called from the thread itself. >> * Per-thread destructors are functions called (from the thread) as the last >> thing when a thread ends. >> >> At this time, I am seeking feedback on the concept and the proposed >> limitations. >> >> Processes have __attribute__(constructor/destructor) to set up functions to >> be called before main(). Nothing similar exists for threads, so we have to >> design it ourselves. >> >> The proposed per-thread constructors/destructors should not apply to all >> threads - only to threads created through the DPDK threads API. Agree? >> >> DPDK has the RTE_INIT()/RTE_FINI() macros for adding process >> constructors/destructors at build time, so I propose a similar API, i.e. >> adding RTE_THREAD_INIT() and RTE_THREAD_FINI() macros to build a list of >> per-thread constructors and destructors at build time. >> >> Two functions that call the list of per-thread constructors respectively >> destructors will be introduced. >> >> The per-thread constructor function will be called from the newly created >> threads within DPDK: >> 1. EAL/SERVICE threads: In eal_thread_loop() before the loop. >> 2. CTRL threads: In ctrl_thread_init() before start_routine(). >> 3. Non-EAL threads: In rte_thread_register(). >> >> Are any thread types missing in the list above? > > I noticed a few drivers doing stuff behind EAL back.. you might want > to grep pthread_create. > They should probably be converted to control threads, or if there is a > reason, it could give more inputs on this topic. > > >> >> >> The per-thread destructor function will also be registered by the per-thread >> constructor, using the POSIX pthread_cleanup_push() function. > > What about Windows?
I don't think there's a need to involve pthread_cleanup_push(). For DPDK-created threads, EAL could run the destructor in a wrapper function. The main lcore's fini callbacks could be run in rte_eal_cleanup(). > Cc: Tyler. > > >> >> >> Examples of where per-thread constructors are useful: >> PRNG state initialization [1]: >> http://inbox.dpdk.org/dev/2a5121c7-369f-afde-0898-d45a5b368...@ericsson.com/ >> PMU event setup [2]: >> http://inbox.dpdk.org/dev/a059c403-8c6c-79c3-c3e9-a8c1815f5...@ericsson.com/T/#m3d29fbc301059f007425ac148a4113e66d2ef983 >> >> >> Please also refer to the discussion [3] about lcore init callbacks for >> further thoughts. Especially the de-facto inability to establish >> constructors/destructors at runtime. >> >> [3]: >> http://inbox.dpdk.org/dev/98cbd80474fa8b44bf855df32c47dc35d87...@smartserver.smartshare.dk/T/#m23b9a930a4050dc6b0305d3653754bd152c09ab7 > > >
