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Tue, 20 Feb 2024 18:52:09 -0800 (PST) Received: from x1n ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id w13-20020a17090aea0d00b00298c17e8135sm8357857pjy.13.2024.02.20.18.52.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Feb 2024 18:52:09 -0800 (PST) Date: Wed, 21 Feb 2024 10:52:02 +0800 From: Peter Xu To: Fabiano Rosas Cc: qemu-devel@nongnu.org Subject: Re: [PATCH] migration: Fix qmp_query_migrate mbps value Message-ID: References: <20240219194457.26923-1-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240219194457.26923-1-farosas@suse.de> 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, 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_H2=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_HELO_TEMPERROR=0.01 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 On Mon, Feb 19, 2024 at 04:44:57PM -0300, Fabiano Rosas wrote: > The QMP command query_migrate might see incorrect throughput numbers > if it runs after we've set the migration completion status but before > migration_calculate_complete() has updated s->total_time and s->mbps. > > The migration status would show COMPLETED, but the throughput value > would be the one from the last iteration and not the one from the > whole migration. This will usually be a larger value due to the time > period being smaller (one iteration). > > Move migration_calculate_complete() earlier so that the status > MIGRATION_STATUS_COMPLETED is only emitted after the final counters > update. > > Signed-off-by: Fabiano Rosas > --- > CI run: https://gitlab.com/farosas/qemu/-/pipelines/1182405776 > --- > migration/migration.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/migration/migration.c b/migration/migration.c > index ab21de2cad..7486d59da0 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -102,6 +102,7 @@ static int migration_maybe_pause(MigrationState *s, > int new_state); > static void migrate_fd_cancel(MigrationState *s); > static bool close_return_path_on_source(MigrationState *s); > +static void migration_calculate_complete(MigrationState *s); > > static void migration_downtime_start(MigrationState *s) > { > @@ -2746,6 +2747,7 @@ static void migration_completion(MigrationState *s) > migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, > MIGRATION_STATUS_COLO); > } else { > + migration_calculate_complete(s); > migrate_set_state(&s->state, current_active_state, > MIGRATION_STATUS_COMPLETED); > } > @@ -2784,6 +2786,7 @@ static void bg_migration_completion(MigrationState *s) > goto fail; > } > > + migration_calculate_complete(s); > migrate_set_state(&s->state, current_active_state, > MIGRATION_STATUS_COMPLETED); > return; > @@ -2993,12 +2996,15 @@ static void migration_calculate_complete(MigrationState *s) > int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > int64_t transfer_time; > > + /* QMP could read from these concurrently */ > + bql_lock(); > migration_downtime_end(s); > s->total_time = end_time - s->start_time; > transfer_time = s->total_time - s->setup_time; > if (transfer_time) { > s->mbps = ((double) bytes * 8.0) / transfer_time / 1000; > } > + bql_unlock(); The lock is not needed? AFAIU that was needed because of things like runstate_set() rather than setting of these fields. See migration_update_counters() where it also updates mbps without holding a lock. Other than that it looks all good. > } > > static void update_iteration_initial_status(MigrationState *s) > @@ -3145,7 +3151,6 @@ static void migration_iteration_finish(MigrationState *s) > bql_lock(); > switch (s->state) { > case MIGRATION_STATUS_COMPLETED: > - migration_calculate_complete(s); > runstate_set(RUN_STATE_POSTMIGRATE); > break; > case MIGRATION_STATUS_COLO: > @@ -3189,9 +3194,6 @@ static void bg_migration_iteration_finish(MigrationState *s) > bql_lock(); > switch (s->state) { > case MIGRATION_STATUS_COMPLETED: > - migration_calculate_complete(s); > - break; > - > case MIGRATION_STATUS_ACTIVE: > case MIGRATION_STATUS_FAILED: > case MIGRATION_STATUS_CANCELLED: > -- > 2.35.3 > -- Peter Xu