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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id x11-20020a0cfe0b000000b0065af657ddf7sm2330515qvr.144.2023.10.22.13.12.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Oct 2023 13:12:39 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Cc: Juan Quintela , Fabiano Rosas , peterx@redhat.com Subject: [PATCH RFC 5/7] migration: Modulize multifd send threads with a few helpers Date: Sun, 22 Oct 2023 16:12:09 -0400 Message-ID: <20231022201211.452861-6-peterx@redhat.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231022201211.452861-1-peterx@redhat.com> References: <20231022201211.452861-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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 Abstract the multifd send packet logic into two phases: - multifd_send_prepare(): prepare the packet headers, with mutex - multifd_do_send(): do the send job finally, without mutex When at it, always allow the send thread to use Error* for detecting errors, dropping "int ret" altogether. One trivial change is the send thread now kicks the sem_sync within mutex critical section, but that shouldn't be a problem. Signed-off-by: Peter Xu --- migration/multifd.c | 160 ++++++++++++++++++++++++++------------------ 1 file changed, 96 insertions(+), 64 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index 9d458914a9..8140520843 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -640,13 +640,89 @@ int multifd_send_sync_main(QEMUFile *f) return 0; } +/* + * Returns true if succeed, false otherwise (with errp set). Caller must + * be with p->mutex held. + */ +static bool multifd_send_prepare(MultiFDSendParams *p, Error **errp) +{ + bool use_zero_copy_send = migrate_zero_copy_send(); + uint64_t packet_num = p->packet_num; + uint32_t flags; + int ret; + + p->normal_num = 0; + + if (use_zero_copy_send) { + p->iovs_num = 0; + } else { + p->iovs_num = 1; + } + + for (int i = 0; i < p->pages->num; i++) { + p->normal[p->normal_num] = p->pages->offset[i]; + p->normal_num++; + } + + if (p->normal_num) { + ret = multifd_send_state->ops->send_prepare(p, errp); + if (ret != 0) { + return false; + } + } + multifd_send_fill_packet(p); + flags = p->flags; + p->flags = 0; + p->num_packets++; + p->total_normal_pages += p->normal_num; + p->pages->num = 0; + p->pages->block = NULL; + + trace_multifd_send(p->id, packet_num, p->normal_num, flags, + p->next_packet_size); + + return true; +} + +/* Returns true if succeed, false otherwise (with errp set) */ +static bool multifd_do_send(MultiFDSendParams *p, Error **errp) +{ + bool use_zero_copy_send = migrate_zero_copy_send(); + int ret; + + if (use_zero_copy_send) { + /* Send header first, without zerocopy */ + ret = qio_channel_write_all(p->c, (void *)p->packet, + p->packet_len, errp); + if (ret != 0) { + return false; + } + } else { + /* Send header using the same writev call */ + p->iov[0].iov_len = p->packet_len; + p->iov[0].iov_base = p->packet; + } + + ret = qio_channel_writev_full_all(p->c, p->iov, p->iovs_num, NULL, + 0, p->write_flags, errp); + if (ret != 0) { + return false; + } + + stat64_add(&mig_stats.multifd_bytes, + p->next_packet_size + p->packet_len); + stat64_add(&mig_stats.transferred, + p->next_packet_size + p->packet_len); + p->next_packet_size = 0; + + return true; +} + static void *multifd_send_thread(void *opaque) { MultiFDSendParams *p = opaque; MigrationThread *thread = NULL; Error *local_err = NULL; - int ret = 0; - bool use_zero_copy_send = migrate_zero_copy_send(); thread = migration_threads_add(p->name, qemu_get_thread_id()); @@ -654,9 +730,10 @@ static void *multifd_send_thread(void *opaque) rcu_register_thread(); if (multifd_send_initial_packet(p, &local_err) < 0) { - ret = -1; + assert(local_err); goto out; } + /* initial packet */ p->num_packets = 1; @@ -667,83 +744,38 @@ static void *multifd_send_thread(void *opaque) if (qatomic_read(&multifd_send_state->exiting)) { break; } - qemu_mutex_lock(&p->mutex); + qemu_mutex_lock(&p->mutex); if (p->pending_job) { - uint64_t packet_num = p->packet_num; - uint32_t flags; - p->normal_num = 0; - - if (use_zero_copy_send) { - p->iovs_num = 0; - } else { - p->iovs_num = 1; - } + bool need_sync = p->flags & MULTIFD_FLAG_SYNC; - for (int i = 0; i < p->pages->num; i++) { - p->normal[p->normal_num] = p->pages->offset[i]; - p->normal_num++; + if (!multifd_send_prepare(p, &local_err)) { + assert(local_err); + qemu_mutex_unlock(&p->mutex); + goto out; } - if (p->normal_num) { - ret = multifd_send_state->ops->send_prepare(p, &local_err); - if (ret != 0) { - qemu_mutex_unlock(&p->mutex); - break; - } - } - multifd_send_fill_packet(p); - flags = p->flags; - p->flags = 0; - p->num_packets++; - p->total_normal_pages += p->normal_num; - p->pages->num = 0; - p->pages->block = NULL; + /* Send the packets without mutex */ qemu_mutex_unlock(&p->mutex); - - trace_multifd_send(p->id, packet_num, p->normal_num, flags, - p->next_packet_size); - - if (use_zero_copy_send) { - /* Send header first, without zerocopy */ - ret = qio_channel_write_all(p->c, (void *)p->packet, - p->packet_len, &local_err); - if (ret != 0) { - break; - } - } else { - /* Send header using the same writev call */ - p->iov[0].iov_len = p->packet_len; - p->iov[0].iov_base = p->packet; + if (!multifd_do_send(p, &local_err)) { + assert(local_err); + goto out; } - - ret = qio_channel_writev_full_all(p->c, p->iov, p->iovs_num, NULL, - 0, p->write_flags, &local_err); - if (ret != 0) { - break; - } - - stat64_add(&mig_stats.multifd_bytes, - p->next_packet_size + p->packet_len); - stat64_add(&mig_stats.transferred, - p->next_packet_size + p->packet_len); - p->next_packet_size = 0; qemu_mutex_lock(&p->mutex); + + /* Send successful, mark the task completed */ p->pending_job--; - qemu_mutex_unlock(&p->mutex); - if (flags & MULTIFD_FLAG_SYNC) { + /* If this is a sync task, we need one more kick */ + if (need_sync) { qemu_sem_post(&p->sem_sync); } - } else { - qemu_mutex_unlock(&p->mutex); - /* sometimes there are spurious wakeups */ } + qemu_mutex_unlock(&p->mutex); } out: - if (ret) { - assert(local_err); + if (local_err) { trace_multifd_send_error(p->id); multifd_send_terminate_threads(local_err); multifd_send_kick_main(p); -- 2.41.0