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Szmigiero" , Peter Xu Cc: Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Eric Blake , Markus Armbruster , =?utf-8?Q?Daniel_P_=2E_Berrang=C3=A9?= , Avihai Horon , Joao Martins , qemu-devel@nongnu.org Subject: Re: [PATCH v3 04/24] thread-pool: Implement generic (non-AIO) pool support In-Reply-To: References: Date: Mon, 25 Nov 2024 16:41:32 -0300 Message-ID: <87ldx7nlsj.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 967ED1F399 X-Rspamd-Action: no action X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; ASN(0.00)[asn:25478, ipnet:::/0, country:RU]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[10]; FUZZY_BLOCKED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:dkim]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org "Maciej S. Szmigiero" writes: > From: "Maciej S. Szmigiero" > > Migration code wants to manage device data sending threads in one place. > > QEMU has an existing thread pool implementation, however it is limited > to queuing AIO operations only and essentially has a 1:1 mapping between > the current AioContext and the AIO ThreadPool in use. > > Implement generic (non-AIO) ThreadPool by essentially wrapping Glib's > GThreadPool. > > This brings a few new operations on a pool: > * thread_pool_wait() operation waits until all the submitted work requests > have finished. > > * thread_pool_set_max_threads() explicitly sets the maximum thread count > in the pool. > > * thread_pool_adjust_max_threads_to_work() adjusts the maximum thread count > in the pool to equal the number of still waiting in queue or unfinished work. > > Signed-off-by: Maciej S. Szmigiero > --- > include/block/thread-pool.h | 9 +++ > util/thread-pool.c | 109 ++++++++++++++++++++++++++++++++++++ > 2 files changed, 118 insertions(+) > > diff --git a/include/block/thread-pool.h b/include/block/thread-pool.h > index 6f27eb085b45..3f9f66307b65 100644 > --- a/include/block/thread-pool.h > +++ b/include/block/thread-pool.h > @@ -38,5 +38,14 @@ BlockAIOCB *thread_pool_submit_aio(ThreadPoolFunc *func, void *arg, > int coroutine_fn thread_pool_submit_co(ThreadPoolFunc *func, void *arg); > void thread_pool_update_params(ThreadPoolAio *pool, struct AioContext *ctx); > > +typedef struct ThreadPool ThreadPool; > + > +ThreadPool *thread_pool_new(void); > +void thread_pool_free(ThreadPool *pool); > +void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, > + void *opaque, GDestroyNotify opaque_destroy); > +void thread_pool_wait(ThreadPool *pool); > +bool thread_pool_set_max_threads(ThreadPool *pool, int max_threads); > +bool thread_pool_adjust_max_threads_to_work(ThreadPool *pool); > > #endif > diff --git a/util/thread-pool.c b/util/thread-pool.c > index 908194dc070f..d80c4181c897 100644 > --- a/util/thread-pool.c > +++ b/util/thread-pool.c > @@ -374,3 +374,112 @@ void thread_pool_free_aio(ThreadPoolAio *pool) > qemu_mutex_destroy(&pool->lock); > g_free(pool); > } > + > +struct ThreadPool { /* type safety */ > + GThreadPool *t; > + size_t unfinished_el_ctr; > + QemuMutex unfinished_el_ctr_mutex; > + QemuCond unfinished_el_ctr_zero_cond; > +}; > + > +typedef struct { > + ThreadPoolFunc *func; > + void *opaque; > + GDestroyNotify opaque_destroy; > +} ThreadPoolElement; > + > +static void thread_pool_func(gpointer data, gpointer user_data) > +{ > + ThreadPool *pool = user_data; > + g_autofree ThreadPoolElement *el = data; > + > + el->func(el->opaque); > + > + if (el->opaque_destroy) { > + el->opaque_destroy(el->opaque); > + } > + > + QEMU_LOCK_GUARD(&pool->unfinished_el_ctr_mutex); > + > + assert(pool->unfinished_el_ctr > 0); > + pool->unfinished_el_ctr--; > + > + if (pool->unfinished_el_ctr == 0) { > + qemu_cond_signal(&pool->unfinished_el_ctr_zero_cond); > + } > +} > + > +ThreadPool *thread_pool_new(void) > +{ > + ThreadPool *pool = g_new(ThreadPool, 1); > + > + pool->unfinished_el_ctr = 0; > + qemu_mutex_init(&pool->unfinished_el_ctr_mutex); > + qemu_cond_init(&pool->unfinished_el_ctr_zero_cond); > + > + pool->t = g_thread_pool_new(thread_pool_func, pool, 0, TRUE, NULL); > + /* > + * g_thread_pool_new() can only return errors if initial thread(s) > + * creation fails but we ask for 0 initial threads above. > + */ > + assert(pool->t); > + > + return pool; > +} > + > +void thread_pool_free(ThreadPool *pool) > +{ > + g_thread_pool_free(pool->t, FALSE, TRUE); Should we make it an error to call thread_poll_free without first calling thread_poll_wait? I worry the current usage will lead to having two different ways of waiting with one of them (this one) being quite implicit. > + > + qemu_cond_destroy(&pool->unfinished_el_ctr_zero_cond); > + qemu_mutex_destroy(&pool->unfinished_el_ctr_mutex); > + > + g_free(pool); > +} > + > +void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, > + void *opaque, GDestroyNotify opaque_destroy) > +{ > + ThreadPoolElement *el = g_new(ThreadPoolElement, 1); > + > + el->func = func; > + el->opaque = opaque; > + el->opaque_destroy = opaque_destroy; > + > + WITH_QEMU_LOCK_GUARD(&pool->unfinished_el_ctr_mutex) { > + pool->unfinished_el_ctr++; > + } > + > + /* > + * Ignore the return value since this function can only return errors > + * if creation of an additional thread fails but even in this case the > + * provided work is still getting queued (just for the existing threads). > + */ > + g_thread_pool_push(pool->t, el, NULL); > +} > + > +void thread_pool_wait(ThreadPool *pool) > +{ > + QEMU_LOCK_GUARD(&pool->unfinished_el_ctr_mutex); > + > + if (pool->unfinished_el_ctr > 0) { > + qemu_cond_wait(&pool->unfinished_el_ctr_zero_cond, > + &pool->unfinished_el_ctr_mutex); > + assert(pool->unfinished_el_ctr == 0); > + } > +} > + > +bool thread_pool_set_max_threads(ThreadPool *pool, > + int max_threads) > +{ > + assert(max_threads > 0); > + > + return g_thread_pool_set_max_threads(pool->t, max_threads, NULL); > +} > + > +bool thread_pool_adjust_max_threads_to_work(ThreadPool *pool) > +{ > + QEMU_LOCK_GUARD(&pool->unfinished_el_ctr_mutex); > + > + return thread_pool_set_max_threads(pool, pool->unfinished_el_ctr); > +}