On Sun, Dec 18, 2022 at 11:01 AM Morten Brørup <[email protected]> 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? Cc: Tyler. > > > Examples of where per-thread constructors are useful: > PRNG state initialization [1]: > http://inbox.dpdk.org/dev/[email protected]/ > PMU event setup [2]: > http://inbox.dpdk.org/dev/[email protected]/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/[email protected]/T/#m23b9a930a4050dc6b0305d3653754bd152c09ab7 -- David Marchand
