migration/migration.c | 13 ++++++++++++ migration/ram.c | 25 +++++++++++++++++----- monitor/hmp-cmds.c | 8 ++++++++ qapi/migration.json | 48 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 89 insertions(+), 5 deletions(-)
At the tail stage of throttling, the Guest is very sensitive to
CPU percentage while the @cpu-throttle-increment is excessive
usually at tail stage.
If this parameter is true, we will compute the ideal CPU percentage
used by the Guest, which may exactly make the dirty rate match the
dirty rate threshold. Then we will choose a smaller throttle increment
between the one specified by @cpu-throttle-increment and the one
generated by ideal CPU percentage.
Therefore, it is compatible to traditional throttling, meanwhile
the throttle increment won't be excessive at tail stage. This may
make migration time longer, and is disabled by default.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
---
Cc: Juan Quintela <quintela@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
---
migration/migration.c | 13 ++++++++++++
migration/ram.c | 25 +++++++++++++++++-----
monitor/hmp-cmds.c | 8 ++++++++
qapi/migration.json | 48 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 89 insertions(+), 5 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 187ac0410c..d478a87290 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -785,6 +785,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
params->cpu_throttle_initial = s->parameters.cpu_throttle_initial;
params->has_cpu_throttle_increment = true;
params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
+ params->has_cpu_throttle_tailslow = true;
+ params->cpu_throttle_tailslow = s->parameters.cpu_throttle_tailslow;
params->has_tls_creds = true;
params->tls_creds = g_strdup(s->parameters.tls_creds);
params->has_tls_hostname = true;
@@ -1324,6 +1326,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
dest->cpu_throttle_increment = params->cpu_throttle_increment;
}
+ if (params->has_cpu_throttle_tailslow) {
+ dest->cpu_throttle_tailslow = params->cpu_throttle_tailslow;
+ }
+
if (params->has_tls_creds) {
assert(params->tls_creds->type == QTYPE_QSTRING);
dest->tls_creds = g_strdup(params->tls_creds->u.s);
@@ -1412,6 +1418,10 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
s->parameters.cpu_throttle_increment = params->cpu_throttle_increment;
}
+ if (params->has_cpu_throttle_tailslow) {
+ s->parameters.cpu_throttle_tailslow = params->cpu_throttle_tailslow;
+ }
+
if (params->has_tls_creds) {
g_free(s->parameters.tls_creds);
assert(params->tls_creds->type == QTYPE_QSTRING);
@@ -3594,6 +3604,8 @@ static Property migration_properties[] = {
DEFINE_PROP_UINT8("x-cpu-throttle-increment", MigrationState,
parameters.cpu_throttle_increment,
DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT),
+ DEFINE_PROP_BOOL("x-cpu-throttle-tailslow", MigrationState,
+ parameters.cpu_throttle_tailslow, false),
DEFINE_PROP_SIZE("x-max-bandwidth", MigrationState,
parameters.max_bandwidth, MAX_THROTTLE),
DEFINE_PROP_UINT64("x-downtime-limit", MigrationState,
@@ -3700,6 +3712,7 @@ static void migration_instance_init(Object *obj)
params->has_throttle_trigger_threshold = true;
params->has_cpu_throttle_initial = true;
params->has_cpu_throttle_increment = true;
+ params->has_cpu_throttle_tailslow = true;
params->has_max_bandwidth = true;
params->has_downtime_limit = true;
params->has_x_checkpoint_delay = true;
diff --git a/migration/ram.c b/migration/ram.c
index 04f13feb2e..3317c99786 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -616,20 +616,34 @@ static size_t save_page_header(RAMState *rs, QEMUFile *f, RAMBlock *block,
* able to complete migration. Some workloads dirty memory way too
* fast and will not effectively converge, even with auto-converge.
*/
-static void mig_throttle_guest_down(void)
+static void mig_throttle_guest_down(uint64_t bytes_dirty_period,
+ uint64_t bytes_dirty_threshold)
{
MigrationState *s = migrate_get_current();
uint64_t pct_initial = s->parameters.cpu_throttle_initial;
- uint64_t pct_icrement = s->parameters.cpu_throttle_increment;
+ uint64_t pct_increment = s->parameters.cpu_throttle_increment;
+ bool pct_tailslow = s->parameters.cpu_throttle_tailslow;
int pct_max = s->parameters.max_cpu_throttle;
+ uint64_t throttle_now = cpu_throttle_get_percentage();
+ uint64_t cpu_now, cpu_ideal, throttle_inc;
+
/* We have not started throttling yet. Let's start it. */
if (!cpu_throttle_active()) {
cpu_throttle_set(pct_initial);
} else {
/* Throttling already on, just increase the rate */
- cpu_throttle_set(MIN(cpu_throttle_get_percentage() + pct_icrement,
- pct_max));
+ if (!pct_tailslow) {
+ throttle_inc = pct_increment;
+ } else {
+ /* Compute the ideal CPU percentage used by Guest, which may
+ * make the dirty rate match the dirty rate threshold. */
+ cpu_now = 100 - throttle_now;
+ cpu_ideal = cpu_now * (bytes_dirty_threshold * 1.0 /
+ bytes_dirty_period);
+ throttle_inc = MIN(cpu_now - cpu_ideal, pct_increment);
+ }
+ cpu_throttle_set(MIN(throttle_now + throttle_inc, pct_max));
}
}
@@ -919,7 +933,8 @@ static void migration_trigger_throttle(RAMState *rs)
(++rs->dirty_rate_high_cnt >= 2)) {
trace_migration_throttle();
rs->dirty_rate_high_cnt = 0;
- mig_throttle_guest_down();
+ mig_throttle_guest_down(bytes_dirty_period,
+ bytes_dirty_threshold);
}
}
}
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 9b94e67879..acd7539273 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -419,6 +419,10 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
monitor_printf(mon, "%s: %u\n",
MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_INCREMENT),
params->cpu_throttle_increment);
+ assert(params->has_cpu_throttle_tailslow);
+ monitor_printf(mon, "%s: %s\n",
+ MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW),
+ params->cpu_throttle_tailslow ? "on" : "off");
assert(params->has_max_cpu_throttle);
monitor_printf(mon, "%s: %u\n",
MigrationParameter_str(MIGRATION_PARAMETER_MAX_CPU_THROTTLE),
@@ -1271,6 +1275,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
p->has_cpu_throttle_increment = true;
visit_type_int(v, param, &p->cpu_throttle_increment, &err);
break;
+ case MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW:
+ p->has_cpu_throttle_tailslow = true;
+ visit_type_bool(v, param, &p->cpu_throttle_tailslow, &err);
+ break;
case MIGRATION_PARAMETER_MAX_CPU_THROTTLE:
p->has_max_cpu_throttle = true;
visit_type_int(v, param, &p->max_cpu_throttle, &err);
diff --git a/qapi/migration.json b/qapi/migration.json
index eca2981d0a..ee6c5a0cae 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -552,6 +552,21 @@
# auto-converge detects that migration is not making
# progress. The default value is 10. (Since 2.7)
#
+# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
+# At the tail stage of throttling, the Guest is very
+# sensitive to CPU percentage while the @cpu-throttle
+# -increment is excessive usually at tail stage.
+# If this parameter is true, we will compute the ideal
+# CPU percentage used by the Guest, which may exactly make
+# the dirty rate match the dirty rate threshold. Then we
+# will choose a smaller throttle increment between the
+# one specified by @cpu-throttle-increment and the one
+# generated by ideal CPU percentage.
+# Therefore, it is compatible to traditional throttling,
+# meanwhile the throttle increment won't be excessive
+# at tail stage.
+# The default value is false. (Since 5.1)
+#
# @tls-creds: ID of the 'tls-creds' object that provides credentials for
# establishing a TLS connection over the migration data channel.
# On the outgoing side of the migration, the credentials must
@@ -631,6 +646,7 @@
'compress-level', 'compress-threads', 'decompress-threads',
'compress-wait-thread', 'throttle-trigger-threshold',
'cpu-throttle-initial', 'cpu-throttle-increment',
+ 'cpu-throttle-tailslow',
'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
'multifd-channels',
@@ -676,6 +692,21 @@
# auto-converge detects that migration is not making
# progress. The default value is 10. (Since 2.7)
#
+# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
+# At the tail stage of throttling, the Guest is very
+# sensitive to CPU percentage while the @cpu-throttle
+# -increment is excessive usually at tail stage.
+# If this parameter is true, we will compute the ideal
+# CPU percentage used by the Guest, which may exactly make
+# the dirty rate match the dirty rate threshold. Then we
+# will choose a smaller throttle increment between the
+# one specified by @cpu-throttle-increment and the one
+# generated by ideal CPU percentage.
+# Therefore, it is compatible to traditional throttling,
+# meanwhile the throttle increment won't be excessive
+# at tail stage.
+# The default value is false. (Since 5.1)
+#
# @tls-creds: ID of the 'tls-creds' object that provides credentials
# for establishing a TLS connection over the migration data
# channel. On the outgoing side of the migration, the credentials
@@ -763,6 +794,7 @@
'*throttle-trigger-threshold': 'int',
'*cpu-throttle-initial': 'int',
'*cpu-throttle-increment': 'int',
+ '*cpu-throttle-tailslow': 'bool',
'*tls-creds': 'StrOrNull',
'*tls-hostname': 'StrOrNull',
'*tls-authz': 'StrOrNull',
@@ -834,6 +866,21 @@
# auto-converge detects that migration is not making
# progress. (Since 2.7)
#
+# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
+# At the tail stage of throttling, the Guest is very
+# sensitive to CPU percentage while the @cpu-throttle
+# -increment is excessive usually at tail stage.
+# If this parameter is true, we will compute the ideal
+# CPU percentage used by the Guest, which may exactly make
+# the dirty rate match the dirty rate threshold. Then we
+# will choose a smaller throttle increment between the
+# one specified by @cpu-throttle-increment and the one
+# generated by ideal CPU percentage.
+# Therefore, it is compatible to traditional throttling,
+# meanwhile the throttle increment won't be excessive
+# at tail stage.
+# The default value is false. (Since 5.1)
+#
# @tls-creds: ID of the 'tls-creds' object that provides credentials
# for establishing a TLS connection over the migration data
# channel. On the outgoing side of the migration, the credentials
@@ -921,6 +968,7 @@
'*throttle-trigger-threshold': 'uint8',
'*cpu-throttle-initial': 'uint8',
'*cpu-throttle-increment': 'uint8',
+ '*cpu-throttle-tailslow': 'bool',
'*tls-creds': 'str',
'*tls-hostname': 'str',
'*tls-authz': 'str',
--
2.19.1
* Keqian Zhu (zhukeqian1@huawei.com) wrote:
> At the tail stage of throttling, the Guest is very sensitive to
> CPU percentage while the @cpu-throttle-increment is excessive
> usually at tail stage.
>
> If this parameter is true, we will compute the ideal CPU percentage
> used by the Guest, which may exactly make the dirty rate match the
> dirty rate threshold. Then we will choose a smaller throttle increment
> between the one specified by @cpu-throttle-increment and the one
> generated by ideal CPU percentage.
>
> Therefore, it is compatible to traditional throttling, meanwhile
> the throttle increment won't be excessive at tail stage. This may
> make migration time longer, and is disabled by default.
>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Queued
> ---
> Cc: Juan Quintela <quintela@redhat.com>
> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>
> Cc: Markus Armbruster <armbru@redhat.com>
> ---
> migration/migration.c | 13 ++++++++++++
> migration/ram.c | 25 +++++++++++++++++-----
> monitor/hmp-cmds.c | 8 ++++++++
> qapi/migration.json | 48 +++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 89 insertions(+), 5 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 187ac0410c..d478a87290 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -785,6 +785,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
> params->cpu_throttle_initial = s->parameters.cpu_throttle_initial;
> params->has_cpu_throttle_increment = true;
> params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
> + params->has_cpu_throttle_tailslow = true;
> + params->cpu_throttle_tailslow = s->parameters.cpu_throttle_tailslow;
> params->has_tls_creds = true;
> params->tls_creds = g_strdup(s->parameters.tls_creds);
> params->has_tls_hostname = true;
> @@ -1324,6 +1326,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
> dest->cpu_throttle_increment = params->cpu_throttle_increment;
> }
>
> + if (params->has_cpu_throttle_tailslow) {
> + dest->cpu_throttle_tailslow = params->cpu_throttle_tailslow;
> + }
> +
> if (params->has_tls_creds) {
> assert(params->tls_creds->type == QTYPE_QSTRING);
> dest->tls_creds = g_strdup(params->tls_creds->u.s);
> @@ -1412,6 +1418,10 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
> s->parameters.cpu_throttle_increment = params->cpu_throttle_increment;
> }
>
> + if (params->has_cpu_throttle_tailslow) {
> + s->parameters.cpu_throttle_tailslow = params->cpu_throttle_tailslow;
> + }
> +
> if (params->has_tls_creds) {
> g_free(s->parameters.tls_creds);
> assert(params->tls_creds->type == QTYPE_QSTRING);
> @@ -3594,6 +3604,8 @@ static Property migration_properties[] = {
> DEFINE_PROP_UINT8("x-cpu-throttle-increment", MigrationState,
> parameters.cpu_throttle_increment,
> DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT),
> + DEFINE_PROP_BOOL("x-cpu-throttle-tailslow", MigrationState,
> + parameters.cpu_throttle_tailslow, false),
> DEFINE_PROP_SIZE("x-max-bandwidth", MigrationState,
> parameters.max_bandwidth, MAX_THROTTLE),
> DEFINE_PROP_UINT64("x-downtime-limit", MigrationState,
> @@ -3700,6 +3712,7 @@ static void migration_instance_init(Object *obj)
> params->has_throttle_trigger_threshold = true;
> params->has_cpu_throttle_initial = true;
> params->has_cpu_throttle_increment = true;
> + params->has_cpu_throttle_tailslow = true;
> params->has_max_bandwidth = true;
> params->has_downtime_limit = true;
> params->has_x_checkpoint_delay = true;
> diff --git a/migration/ram.c b/migration/ram.c
> index 04f13feb2e..3317c99786 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -616,20 +616,34 @@ static size_t save_page_header(RAMState *rs, QEMUFile *f, RAMBlock *block,
> * able to complete migration. Some workloads dirty memory way too
> * fast and will not effectively converge, even with auto-converge.
> */
> -static void mig_throttle_guest_down(void)
> +static void mig_throttle_guest_down(uint64_t bytes_dirty_period,
> + uint64_t bytes_dirty_threshold)
> {
> MigrationState *s = migrate_get_current();
> uint64_t pct_initial = s->parameters.cpu_throttle_initial;
> - uint64_t pct_icrement = s->parameters.cpu_throttle_increment;
> + uint64_t pct_increment = s->parameters.cpu_throttle_increment;
> + bool pct_tailslow = s->parameters.cpu_throttle_tailslow;
> int pct_max = s->parameters.max_cpu_throttle;
>
> + uint64_t throttle_now = cpu_throttle_get_percentage();
> + uint64_t cpu_now, cpu_ideal, throttle_inc;
> +
> /* We have not started throttling yet. Let's start it. */
> if (!cpu_throttle_active()) {
> cpu_throttle_set(pct_initial);
> } else {
> /* Throttling already on, just increase the rate */
> - cpu_throttle_set(MIN(cpu_throttle_get_percentage() + pct_icrement,
> - pct_max));
> + if (!pct_tailslow) {
> + throttle_inc = pct_increment;
> + } else {
> + /* Compute the ideal CPU percentage used by Guest, which may
> + * make the dirty rate match the dirty rate threshold. */
> + cpu_now = 100 - throttle_now;
> + cpu_ideal = cpu_now * (bytes_dirty_threshold * 1.0 /
> + bytes_dirty_period);
> + throttle_inc = MIN(cpu_now - cpu_ideal, pct_increment);
> + }
> + cpu_throttle_set(MIN(throttle_now + throttle_inc, pct_max));
> }
> }
>
> @@ -919,7 +933,8 @@ static void migration_trigger_throttle(RAMState *rs)
> (++rs->dirty_rate_high_cnt >= 2)) {
> trace_migration_throttle();
> rs->dirty_rate_high_cnt = 0;
> - mig_throttle_guest_down();
> + mig_throttle_guest_down(bytes_dirty_period,
> + bytes_dirty_threshold);
> }
> }
> }
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 9b94e67879..acd7539273 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -419,6 +419,10 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
> monitor_printf(mon, "%s: %u\n",
> MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_INCREMENT),
> params->cpu_throttle_increment);
> + assert(params->has_cpu_throttle_tailslow);
> + monitor_printf(mon, "%s: %s\n",
> + MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW),
> + params->cpu_throttle_tailslow ? "on" : "off");
> assert(params->has_max_cpu_throttle);
> monitor_printf(mon, "%s: %u\n",
> MigrationParameter_str(MIGRATION_PARAMETER_MAX_CPU_THROTTLE),
> @@ -1271,6 +1275,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
> p->has_cpu_throttle_increment = true;
> visit_type_int(v, param, &p->cpu_throttle_increment, &err);
> break;
> + case MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW:
> + p->has_cpu_throttle_tailslow = true;
> + visit_type_bool(v, param, &p->cpu_throttle_tailslow, &err);
> + break;
> case MIGRATION_PARAMETER_MAX_CPU_THROTTLE:
> p->has_max_cpu_throttle = true;
> visit_type_int(v, param, &p->max_cpu_throttle, &err);
> diff --git a/qapi/migration.json b/qapi/migration.json
> index eca2981d0a..ee6c5a0cae 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -552,6 +552,21 @@
> # auto-converge detects that migration is not making
> # progress. The default value is 10. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials for
> # establishing a TLS connection over the migration data channel.
> # On the outgoing side of the migration, the credentials must
> @@ -631,6 +646,7 @@
> 'compress-level', 'compress-threads', 'decompress-threads',
> 'compress-wait-thread', 'throttle-trigger-threshold',
> 'cpu-throttle-initial', 'cpu-throttle-increment',
> + 'cpu-throttle-tailslow',
> 'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
> 'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
> 'multifd-channels',
> @@ -676,6 +692,21 @@
> # auto-converge detects that migration is not making
> # progress. The default value is 10. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials
> # for establishing a TLS connection over the migration data
> # channel. On the outgoing side of the migration, the credentials
> @@ -763,6 +794,7 @@
> '*throttle-trigger-threshold': 'int',
> '*cpu-throttle-initial': 'int',
> '*cpu-throttle-increment': 'int',
> + '*cpu-throttle-tailslow': 'bool',
> '*tls-creds': 'StrOrNull',
> '*tls-hostname': 'StrOrNull',
> '*tls-authz': 'StrOrNull',
> @@ -834,6 +866,21 @@
> # auto-converge detects that migration is not making
> # progress. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials
> # for establishing a TLS connection over the migration data
> # channel. On the outgoing side of the migration, the credentials
> @@ -921,6 +968,7 @@
> '*throttle-trigger-threshold': 'uint8',
> '*cpu-throttle-initial': 'uint8',
> '*cpu-throttle-increment': 'uint8',
> + '*cpu-throttle-tailslow': 'bool',
> '*tls-creds': 'str',
> '*tls-hostname': 'str',
> '*tls-authz': 'str',
> --
> 2.19.1
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
* Keqian Zhu (zhukeqian1@huawei.com) wrote:
> At the tail stage of throttling, the Guest is very sensitive to
> CPU percentage while the @cpu-throttle-increment is excessive
> usually at tail stage.
>
> If this parameter is true, we will compute the ideal CPU percentage
> used by the Guest, which may exactly make the dirty rate match the
> dirty rate threshold. Then we will choose a smaller throttle increment
> between the one specified by @cpu-throttle-increment and the one
> generated by ideal CPU percentage.
>
> Therefore, it is compatible to traditional throttling, meanwhile
> the throttle increment won't be excessive at tail stage. This may
> make migration time longer, and is disabled by default.
>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
So I think this is OK; see comment below.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> Cc: Juan Quintela <quintela@redhat.com>
> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>
> Cc: Markus Armbruster <armbru@redhat.com>
> ---
> migration/migration.c | 13 ++++++++++++
> migration/ram.c | 25 +++++++++++++++++-----
> monitor/hmp-cmds.c | 8 ++++++++
> qapi/migration.json | 48 +++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 89 insertions(+), 5 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 187ac0410c..d478a87290 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -785,6 +785,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
> params->cpu_throttle_initial = s->parameters.cpu_throttle_initial;
> params->has_cpu_throttle_increment = true;
> params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
> + params->has_cpu_throttle_tailslow = true;
> + params->cpu_throttle_tailslow = s->parameters.cpu_throttle_tailslow;
> params->has_tls_creds = true;
> params->tls_creds = g_strdup(s->parameters.tls_creds);
> params->has_tls_hostname = true;
> @@ -1324,6 +1326,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
> dest->cpu_throttle_increment = params->cpu_throttle_increment;
> }
>
> + if (params->has_cpu_throttle_tailslow) {
> + dest->cpu_throttle_tailslow = params->cpu_throttle_tailslow;
> + }
> +
> if (params->has_tls_creds) {
> assert(params->tls_creds->type == QTYPE_QSTRING);
> dest->tls_creds = g_strdup(params->tls_creds->u.s);
> @@ -1412,6 +1418,10 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
> s->parameters.cpu_throttle_increment = params->cpu_throttle_increment;
> }
>
> + if (params->has_cpu_throttle_tailslow) {
> + s->parameters.cpu_throttle_tailslow = params->cpu_throttle_tailslow;
> + }
> +
> if (params->has_tls_creds) {
> g_free(s->parameters.tls_creds);
> assert(params->tls_creds->type == QTYPE_QSTRING);
> @@ -3594,6 +3604,8 @@ static Property migration_properties[] = {
> DEFINE_PROP_UINT8("x-cpu-throttle-increment", MigrationState,
> parameters.cpu_throttle_increment,
> DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT),
> + DEFINE_PROP_BOOL("x-cpu-throttle-tailslow", MigrationState,
> + parameters.cpu_throttle_tailslow, false),
> DEFINE_PROP_SIZE("x-max-bandwidth", MigrationState,
> parameters.max_bandwidth, MAX_THROTTLE),
> DEFINE_PROP_UINT64("x-downtime-limit", MigrationState,
> @@ -3700,6 +3712,7 @@ static void migration_instance_init(Object *obj)
> params->has_throttle_trigger_threshold = true;
> params->has_cpu_throttle_initial = true;
> params->has_cpu_throttle_increment = true;
> + params->has_cpu_throttle_tailslow = true;
> params->has_max_bandwidth = true;
> params->has_downtime_limit = true;
> params->has_x_checkpoint_delay = true;
> diff --git a/migration/ram.c b/migration/ram.c
> index 04f13feb2e..3317c99786 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -616,20 +616,34 @@ static size_t save_page_header(RAMState *rs, QEMUFile *f, RAMBlock *block,
> * able to complete migration. Some workloads dirty memory way too
> * fast and will not effectively converge, even with auto-converge.
> */
> -static void mig_throttle_guest_down(void)
> +static void mig_throttle_guest_down(uint64_t bytes_dirty_period,
> + uint64_t bytes_dirty_threshold)
> {
> MigrationState *s = migrate_get_current();
> uint64_t pct_initial = s->parameters.cpu_throttle_initial;
> - uint64_t pct_icrement = s->parameters.cpu_throttle_increment;
> + uint64_t pct_increment = s->parameters.cpu_throttle_increment;
> + bool pct_tailslow = s->parameters.cpu_throttle_tailslow;
> int pct_max = s->parameters.max_cpu_throttle;
>
> + uint64_t throttle_now = cpu_throttle_get_percentage();
> + uint64_t cpu_now, cpu_ideal, throttle_inc;
> +
> /* We have not started throttling yet. Let's start it. */
> if (!cpu_throttle_active()) {
> cpu_throttle_set(pct_initial);
> } else {
> /* Throttling already on, just increase the rate */
> - cpu_throttle_set(MIN(cpu_throttle_get_percentage() + pct_icrement,
> - pct_max));
> + if (!pct_tailslow) {
> + throttle_inc = pct_increment;
> + } else {
> + /* Compute the ideal CPU percentage used by Guest, which may
> + * make the dirty rate match the dirty rate threshold. */
> + cpu_now = 100 - throttle_now;
> + cpu_ideal = cpu_now * (bytes_dirty_threshold * 1.0 /
> + bytes_dirty_period);
I worry if we need a divide-by-0 check; but that seems unlikely.
Now if that worked out as huge, then I think the MIN's guard it even
with overflow below, so I think we're OK.
> + throttle_inc = MIN(cpu_now - cpu_ideal, pct_increment);
> + }
> + cpu_throttle_set(MIN(throttle_now + throttle_inc, pct_max));
> }
> }
>
> @@ -919,7 +933,8 @@ static void migration_trigger_throttle(RAMState *rs)
> (++rs->dirty_rate_high_cnt >= 2)) {
> trace_migration_throttle();
> rs->dirty_rate_high_cnt = 0;
> - mig_throttle_guest_down();
> + mig_throttle_guest_down(bytes_dirty_period,
> + bytes_dirty_threshold);
> }
> }
> }
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 9b94e67879..acd7539273 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -419,6 +419,10 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
> monitor_printf(mon, "%s: %u\n",
> MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_INCREMENT),
> params->cpu_throttle_increment);
> + assert(params->has_cpu_throttle_tailslow);
> + monitor_printf(mon, "%s: %s\n",
> + MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW),
> + params->cpu_throttle_tailslow ? "on" : "off");
> assert(params->has_max_cpu_throttle);
> monitor_printf(mon, "%s: %u\n",
> MigrationParameter_str(MIGRATION_PARAMETER_MAX_CPU_THROTTLE),
> @@ -1271,6 +1275,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
> p->has_cpu_throttle_increment = true;
> visit_type_int(v, param, &p->cpu_throttle_increment, &err);
> break;
> + case MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW:
> + p->has_cpu_throttle_tailslow = true;
> + visit_type_bool(v, param, &p->cpu_throttle_tailslow, &err);
> + break;
> case MIGRATION_PARAMETER_MAX_CPU_THROTTLE:
> p->has_max_cpu_throttle = true;
> visit_type_int(v, param, &p->max_cpu_throttle, &err);
> diff --git a/qapi/migration.json b/qapi/migration.json
> index eca2981d0a..ee6c5a0cae 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -552,6 +552,21 @@
> # auto-converge detects that migration is not making
> # progress. The default value is 10. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials for
> # establishing a TLS connection over the migration data channel.
> # On the outgoing side of the migration, the credentials must
> @@ -631,6 +646,7 @@
> 'compress-level', 'compress-threads', 'decompress-threads',
> 'compress-wait-thread', 'throttle-trigger-threshold',
> 'cpu-throttle-initial', 'cpu-throttle-increment',
> + 'cpu-throttle-tailslow',
> 'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
> 'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
> 'multifd-channels',
> @@ -676,6 +692,21 @@
> # auto-converge detects that migration is not making
> # progress. The default value is 10. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials
> # for establishing a TLS connection over the migration data
> # channel. On the outgoing side of the migration, the credentials
> @@ -763,6 +794,7 @@
> '*throttle-trigger-threshold': 'int',
> '*cpu-throttle-initial': 'int',
> '*cpu-throttle-increment': 'int',
> + '*cpu-throttle-tailslow': 'bool',
> '*tls-creds': 'StrOrNull',
> '*tls-hostname': 'StrOrNull',
> '*tls-authz': 'StrOrNull',
> @@ -834,6 +866,21 @@
> # auto-converge detects that migration is not making
> # progress. (Since 2.7)
> #
> +# @cpu-throttle-tailslow: Make CPU throttling slower at tail stage
> +# At the tail stage of throttling, the Guest is very
> +# sensitive to CPU percentage while the @cpu-throttle
> +# -increment is excessive usually at tail stage.
> +# If this parameter is true, we will compute the ideal
> +# CPU percentage used by the Guest, which may exactly make
> +# the dirty rate match the dirty rate threshold. Then we
> +# will choose a smaller throttle increment between the
> +# one specified by @cpu-throttle-increment and the one
> +# generated by ideal CPU percentage.
> +# Therefore, it is compatible to traditional throttling,
> +# meanwhile the throttle increment won't be excessive
> +# at tail stage.
> +# The default value is false. (Since 5.1)
> +#
> # @tls-creds: ID of the 'tls-creds' object that provides credentials
> # for establishing a TLS connection over the migration data
> # channel. On the outgoing side of the migration, the credentials
> @@ -921,6 +968,7 @@
> '*throttle-trigger-threshold': 'uint8',
> '*cpu-throttle-initial': 'uint8',
> '*cpu-throttle-increment': 'uint8',
> + '*cpu-throttle-tailslow': 'bool',
> '*tls-creds': 'str',
> '*tls-hostname': 'str',
> '*tls-authz': 'str',
> --
> 2.19.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Hi Dr.David,
Sorry for the reply delay, just come back from holiday.
On 2020/4/30 22:12, Dr. David Alan Gilbert wrote:
> * Keqian Zhu (zhukeqian1@huawei.com) wrote:
>> At the tail stage of throttling, the Guest is very sensitive to
>> CPU percentage while the @cpu-throttle-increment is excessive
>> usually at tail stage.
[...]
>> -static void mig_throttle_guest_down(void)
>> +static void mig_throttle_guest_down(uint64_t bytes_dirty_period,
>> + uint64_t bytes_dirty_threshold)
>> {
>> MigrationState *s = migrate_get_current();
>> uint64_t pct_initial = s->parameters.cpu_throttle_initial;
>> - uint64_t pct_icrement = s->parameters.cpu_throttle_increment;
>> + uint64_t pct_increment = s->parameters.cpu_throttle_increment;
>> + bool pct_tailslow = s->parameters.cpu_throttle_tailslow;
>> int pct_max = s->parameters.max_cpu_throttle;
>>
>> + uint64_t throttle_now = cpu_throttle_get_percentage();
>> + uint64_t cpu_now, cpu_ideal, throttle_inc;
>> +
>> /* We have not started throttling yet. Let's start it. */
>> if (!cpu_throttle_active()) {
>> cpu_throttle_set(pct_initial);
>> } else {
>> /* Throttling already on, just increase the rate */
>> - cpu_throttle_set(MIN(cpu_throttle_get_percentage() + pct_icrement,
>> - pct_max));
>> + if (!pct_tailslow) {
>> + throttle_inc = pct_increment;
>> + } else {
>> + /* Compute the ideal CPU percentage used by Guest, which may
>> + * make the dirty rate match the dirty rate threshold. */
>> + cpu_now = 100 - throttle_now;
>> + cpu_ideal = cpu_now * (bytes_dirty_threshold * 1.0 /
>> + bytes_dirty_period);
>
> I worry if we need a divide-by-0 check; but that seems unlikely.
mig_throttle_guest_down is called when bytes_dirty_period is bigger than
bytes_dirty_threshold, and bytes_dirty_threshold is of unsigned type, so
bytes_dirty_period will not be zero here. I will add an assert check here
to make it clear.
> Now if that worked out as huge, then I think the MIN's guard it even
> with overflow below, so I think we're OK.
Yes, it will not exceed legacy increment.
>
>> + throttle_inc = MIN(cpu_now - cpu_ideal, pct_increment);
>> + }
>> + cpu_throttle_set(MIN(throttle_now + throttle_inc, pct_max));
>> }
>> }
>>
[...]
>> --
>> 2.19.1
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
Thanks,
Keqian
>
> .
>
© 2016 - 2024 Red Hat, Inc.