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Mon, 24 Feb 2020 12:06:04 +0800 (CST) Received: from dggeme758-chm.china.huawei.com (10.3.19.104) by DGGEMM404-HUB.china.huawei.com (10.3.20.212) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 24 Feb 2020 12:06:04 +0800 Received: from dggeme756-chm.china.huawei.com (10.3.19.102) by dggeme758-chm.china.huawei.com (10.3.19.104) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Mon, 24 Feb 2020 12:06:03 +0800 Received: from dggeme756-chm.china.huawei.com ([10.6.80.68]) by dggeme756-chm.china.huawei.com ([10.6.80.68]) with mapi id 15.01.1713.004; Mon, 24 Feb 2020 12:06:03 +0800 From: Zhanghailiang To: "Dr. David Alan Gilbert" Subject: RE: [PATCH 2/3] COLO: Migrate dirty pages during the gap of checkpointing Thread-Topic: [PATCH 2/3] COLO: Migrate dirty pages during the gap of checkpointing Thread-Index: AQHV5TCSFfzxcgsk4EWoL4ZepiiUW6giWqSAgAdkO5A= Date: Mon, 24 Feb 2020 04:06:03 +0000 Message-ID: References: <20200217012049.22988-1-zhang.zhanghailiang@huawei.com> <20200217012049.22988-3-zhang.zhanghailiang@huawei.com> <20200219185117.GJ3089@work-vm> In-Reply-To: <20200219185117.GJ3089@work-vm> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.133.214.142] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-CFilter-Loop: Reflected X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 45.249.212.188 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "danielcho@qnap.com" , "chen.zhang@intel.com" , "qemu-devel@nongnu.org" , "quintela@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" > -----Original Message----- > From: Dr. David Alan Gilbert [mailto:dgilbert@redhat.com] > Sent: Thursday, February 20, 2020 2:51 AM > To: Zhanghailiang > Cc: qemu-devel@nongnu.org; quintela@redhat.com; chen.zhang@intel.com; > danielcho@qnap.com > Subject: Re: [PATCH 2/3] COLO: Migrate dirty pages during the gap of > checkpointing >=20 > * Hailiang Zhang (zhang.zhanghailiang@huawei.com) wrote: > > We can migrate some dirty pages during the gap of checkpointing, > > by this way, we can reduce the amount of ram migrated during > checkpointing. > > > > Signed-off-by: Hailiang Zhang > > --- > > migration/colo.c | 69 > +++++++++++++++++++++++++++++++++++++++--- > > migration/migration.h | 1 + > > migration/trace-events | 1 + > > qapi/migration.json | 4 ++- > > 4 files changed, 70 insertions(+), 5 deletions(-) > > > > diff --git a/migration/colo.c b/migration/colo.c > > index 93c5a452fb..d30c6bc4ad 100644 > > --- a/migration/colo.c > > +++ b/migration/colo.c > > @@ -46,6 +46,13 @@ static COLOMode last_colo_mode; > > > > #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024) > > > > +#define DEFAULT_RAM_PENDING_CHECK 1000 > > + > > +/* should be calculated by bandwidth and max downtime ? */ > > +#define THRESHOLD_PENDING_SIZE (100 * 1024 * 1024UL) >=20 > Turn both of these magic constants into parameters. >=20 Good idea, will do this in later patches. > > +static int checkpoint_request; > > + > > bool migration_in_colo_state(void) > > { > > MigrationState *s =3D migrate_get_current(); > > @@ -516,6 +523,20 @@ static void > colo_compare_notify_checkpoint(Notifier *notifier, void *data) > > colo_checkpoint_notify(data); > > } > > > > +static bool colo_need_migrate_ram_background(MigrationState *s) > > +{ > > + uint64_t pending_size, pend_pre, pend_compat, pend_post; > > + int64_t max_size =3D THRESHOLD_PENDING_SIZE; > > + > > + qemu_savevm_state_pending(s->to_dst_file, max_size, &pend_pre, > > + &pend_compat, &pend_post); > > + pending_size =3D pend_pre + pend_compat + pend_post; > > + > > + trace_colo_need_migrate_ram_background(pending_size); > > + return (pending_size >=3D max_size); > > +} > > + > > + > > static void colo_process_checkpoint(MigrationState *s) > > { > > QIOChannelBuffer *bioc; > > @@ -571,6 +592,8 @@ static void > colo_process_checkpoint(MigrationState *s) > > > > timer_mod(s->colo_delay_timer, > > current_time + s->parameters.x_checkpoint_delay); > > + timer_mod(s->pending_ram_check_timer, > > + current_time + DEFAULT_RAM_PENDING_CHECK); >=20 > What happens if the iterate takes a while and this triggers in the > middle of the iterate? >=20 It will trigger another iterate after this one been finished. > > while (s->state =3D=3D MIGRATION_STATUS_COLO) { > > if (failover_get_state() !=3D FAILOVER_STATUS_NONE) { > > @@ -583,10 +606,25 @@ static void > colo_process_checkpoint(MigrationState *s) > > if (s->state !=3D MIGRATION_STATUS_COLO) { > > goto out; > > } > > - ret =3D colo_do_checkpoint_transaction(s, bioc, fb); > > - if (ret < 0) { > > - goto out; > > - } > > + if (atomic_xchg(&checkpoint_request, 0)) { > > + /* start a colo checkpoint */ > > + ret =3D colo_do_checkpoint_transaction(s, bioc, fb); > > + if (ret < 0) { > > + goto out; > > + } > > + } else { > > + if (colo_need_migrate_ram_background(s)) { > > + colo_send_message(s->to_dst_file, > > + > COLO_MESSAGE_MIGRATE_RAM_BACKGROUND, > > + &local_err); > > + if (local_err) { > > + goto out; > > + } > > + > > + qemu_savevm_state_iterate(s->to_dst_file, false); > > + qemu_put_byte(s->to_dst_file, QEMU_VM_EOF); >=20 > Maybe you should do a qemu_file_get_error(..) at this point to check > it's OK. Agreed, we should check it. >=20 > > + } > > + } > > } > > > > out: > > @@ -626,6 +664,8 @@ out: > > colo_compare_unregister_notifier(&packets_compare_notifier); > > timer_del(s->colo_delay_timer); > > timer_free(s->colo_delay_timer); > > + timer_del(s->pending_ram_check_timer); > > + timer_free(s->pending_ram_check_timer); > > qemu_sem_destroy(&s->colo_checkpoint_sem); > > > > /* > > @@ -643,6 +683,7 @@ void colo_checkpoint_notify(void *opaque) > > MigrationState *s =3D opaque; > > int64_t next_notify_time; > > > > + atomic_inc(&checkpoint_request); >=20 > Can you explain what you've changed about this atomic in this patch, > I don't quite see what you're doing. >=20 We use this to check who waked it from waiting for colo_checkpoint_sem, By background migration request or checkpoint request. If the value is zero, it is waked by background migration request, or it is= waked By checkpoint request. > > qemu_sem_post(&s->colo_checkpoint_sem); > > s->colo_checkpoint_time =3D > qemu_clock_get_ms(QEMU_CLOCK_HOST); > > next_notify_time =3D s->colo_checkpoint_time + > > @@ -650,6 +691,19 @@ void colo_checkpoint_notify(void *opaque) > > timer_mod(s->colo_delay_timer, next_notify_time); > > } > > > > +static void colo_pending_ram_check_notify(void *opaque) > > +{ > > + int64_t next_notify_time; > > + MigrationState *s =3D opaque; > > + > > + if (migration_in_colo_state()) { > > + next_notify_time =3D DEFAULT_RAM_PENDING_CHECK + > > + > qemu_clock_get_ms(QEMU_CLOCK_HOST); > > + timer_mod(s->pending_ram_check_timer, next_notify_time); > > + qemu_sem_post(&s->colo_checkpoint_sem); > > + } > > +} > > + > > void migrate_start_colo_process(MigrationState *s) > > { > > qemu_mutex_unlock_iothread(); > > @@ -657,6 +711,8 @@ void migrate_start_colo_process(MigrationState > *s) > > s->colo_delay_timer =3D timer_new_ms(QEMU_CLOCK_HOST, > > colo_checkpoint_notify, s); > > > > + s->pending_ram_check_timer =3D > timer_new_ms(QEMU_CLOCK_HOST, > > + colo_pending_ram_check_notify, s); > > qemu_sem_init(&s->colo_exit_sem, 0); > > migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, > > MIGRATION_STATUS_COLO); > > @@ -805,6 +861,11 @@ static void > colo_wait_handle_message(MigrationIncomingState *mis, > > case COLO_MESSAGE_CHECKPOINT_REQUEST: > > colo_incoming_process_checkpoint(mis, fb, bioc, errp); > > break; > > + case COLO_MESSAGE_MIGRATE_RAM_BACKGROUND: > > + if (qemu_loadvm_state_main(mis->from_src_file, mis) < 0) { > > + error_setg(errp, "Load ram background failed"); > > + } >=20 > OK, that's a little dangerou, in that it relies on the source being good > and only sending iterative data; stuff would break badly if it actually > sent you devices. >=20 You are right, we should check it, besides we should have a timeout mechani= sm to avoid been stuck here.=20 > > + break; > > default: > > error_setg(errp, "Got unknown COLO message: %d", msg); > > break; > > diff --git a/migration/migration.h b/migration/migration.h > > index 8473ddfc88..5355259789 100644 > > --- a/migration/migration.h > > +++ b/migration/migration.h > > @@ -219,6 +219,7 @@ struct MigrationState > > QemuSemaphore colo_checkpoint_sem; > > int64_t colo_checkpoint_time; > > QEMUTimer *colo_delay_timer; > > + QEMUTimer *pending_ram_check_timer; > > > > /* The first error that has occurred. > > We used the mutex to be able to return the 1st error message */ > > diff --git a/migration/trace-events b/migration/trace-events > > index 4ab0a503d2..f2ed0c8645 100644 > > --- a/migration/trace-events > > +++ b/migration/trace-events > > @@ -295,6 +295,7 @@ > migration_tls_incoming_handshake_complete(void) "" > > colo_vm_state_change(const char *old, const char *new) "Change '%s' = =3D> > '%s'" > > colo_send_message(const char *msg) "Send '%s' message" > > colo_receive_message(const char *msg) "Receive '%s' message" > > +colo_need_migrate_ram_background(uint64_t pending_size) "Pending > 0x%" PRIx64 " dirty ram" > > > > # colo-failover.c > > colo_failover_set_state(const char *new_state) "new state %s" > > diff --git a/qapi/migration.json b/qapi/migration.json > > index b7348d0c8b..ff7a4f18b0 100644 > > --- a/qapi/migration.json > > +++ b/qapi/migration.json > > @@ -977,12 +977,14 @@ > > # > > # @vmstate-loaded: VM's state has been loaded by SVM. > > # > > +# @migrate-ram-background: Send some dirty pages during the gap of > COLO checkpoint > > +# > > # Since: 2.8 > > ## > > { 'enum': 'COLOMessage', > > 'data': [ 'checkpoint-ready', 'checkpoint-request', 'checkpoint-repl= y', > > 'vmstate-send', 'vmstate-size', 'vmstate-received', > > - 'vmstate-loaded' ] } > > + 'vmstate-loaded', 'migrate-ram-background' ] } > > > > ## > > # @COLOMode: > > -- > > 2.21.0 > > > > > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK