From: Hyman Huang(黄勇) <yong.hu...@smartx.com>
Introduce migration dirty-limit capability, which can
be turned on before live migration and limit dirty
page rate durty live migration.
Introduce migrate_dirty_limit function to help check
if dirty-limit capability enabled during live migration.
Meanwhile, refactor vcpu_dirty_rate_stat_collect
so that period can be configured instead of hardcoded.
dirty-limit capability is kind of like auto-converge
but using dirty limit instead of traditional cpu-throttle
to throttle guest down. To enable this feature, turn on
the dirty-limit capability before live migration using
migrate-set-capabilities, and set the parameters
"x-vcpu-dirty-limit-period", "vcpu-dirty-limit" suitably
to speed up convergence.
Signed-off-by: Hyman Huang(黄勇) <yong.hu...@smartx.com>
Acked-by: Peter Xu <pet...@redhat.com>
Reviewed-by: Juan Quintela <quint...@redhat.com>
---
migration/options.c | 24 ++++++++++++++++++++++++
migration/options.h | 1 +
qapi/migration.json | 13 ++++++++++++-
softmmu/dirtylimit.c | 12 +++++++++++-
4 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/migration/options.c b/migration/options.c
index 7d2d98830e..8b4eb8c519 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -27,6 +27,7 @@
#include "qemu-file.h"
#include "ram.h"
#include "options.h"
+#include "sysemu/kvm.h"
/* Maximum migrate downtime set to 2000 seconds */
#define MAX_MIGRATE_DOWNTIME_SECONDS 2000
@@ -196,6 +197,8 @@ Property migration_properties[] = {
#endif
DEFINE_PROP_MIG_CAP("x-switchover-ack",
MIGRATION_CAPABILITY_SWITCHOVER_ACK),
+ DEFINE_PROP_MIG_CAP("x-dirty-limit",
+ MIGRATION_CAPABILITY_DIRTY_LIMIT),
DEFINE_PROP_END_OF_LIST(),
};
@@ -242,6 +245,13 @@ bool migrate_dirty_bitmaps(void)
return s->capabilities[MIGRATION_CAPABILITY_DIRTY_BITMAPS];
}
+bool migrate_dirty_limit(void)
+{
+ MigrationState *s = migrate_get_current();
+
+ return s->capabilities[MIGRATION_CAPABILITY_DIRTY_LIMIT];
+}
+
bool migrate_events(void)
{
MigrationState *s = migrate_get_current();
@@ -573,6 +583,20 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps,
Error **errp)
}
}
+ if (new_caps[MIGRATION_CAPABILITY_DIRTY_LIMIT]) {
+ if (new_caps[MIGRATION_CAPABILITY_AUTO_CONVERGE]) {
+ error_setg(errp, "dirty-limit conflicts with auto-converge"
+ " either of then available currently");
+ return false;
+ }
+
+ if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
+ error_setg(errp, "dirty-limit requires KVM with accelerator"
+ " property 'dirty-ring-size' set");
+ return false;
+ }
+ }
+
return true;
}
diff --git a/migration/options.h b/migration/options.h
index 9aaf363322..b5a950d4e4 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -24,6 +24,7 @@ extern Property migration_properties[];
/* capabilities */
bool migrate_auto_converge(void);
+bool migrate_dirty_limit(void);
bool migrate_background_snapshot(void);
bool migrate_block(void);
bool migrate_colo(void);
diff --git a/qapi/migration.json b/qapi/migration.json
index aa590dbf0e..cc51835cdd 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -497,6 +497,16 @@
# are present. 'return-path' capability must be enabled to use
# it. (since 8.1)
#
+# @dirty-limit: If enabled, migration will use the dirty-limit algo to
+# throttle down guest instead of auto-converge algo.
+# Throttle algo only works when vCPU's dirtyrate greater
+# than 'vcpu-dirty-limit', read processes in guest os
+# aren't penalized any more, so this algo can improve
+# performance of vCPU during live migration. This is an
+# optional performance feature and should not affect the
+# correctness of the existing auto-converge algo.
+# (since 8.1)
+#
# Features:
#
# @unstable: Members @x-colo and @x-ignore-shared are experimental.
@@ -512,7 +522,8 @@
'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
{ 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
'validate-uuid', 'background-snapshot',
- 'zero-copy-send', 'postcopy-preempt', 'switchover-ack'] }
+ 'zero-copy-send', 'postcopy-preempt', 'switchover-ack',
+ 'dirty-limit'] }
##
# @MigrationCapabilityStatus:
diff --git a/softmmu/dirtylimit.c b/softmmu/dirtylimit.c
index 5c12d26d49..953ef934bc 100644
--- a/softmmu/dirtylimit.c
+++ b/softmmu/dirtylimit.c
@@ -24,6 +24,9 @@
#include "hw/boards.h"
#include "sysemu/kvm.h"
#include "trace.h"
+#include "migration/misc.h"
+#include "migration/migration.h"
+#include "migration/options.h"
/*
* Dirtylimit stop working if dirty page rate error
@@ -75,11 +78,18 @@ static bool dirtylimit_quit;
static void vcpu_dirty_rate_stat_collect(void)
{
+ MigrationState *s = migrate_get_current();
VcpuStat stat;
int i = 0;
+ int64_t period = DIRTYLIMIT_CALC_TIME_MS;
+
+ if (migrate_dirty_limit() &&
+ migration_is_active(s)) {
+ period = s->parameters.x_vcpu_dirty_limit_period;
+ }
/* calculate vcpu dirtyrate */
- vcpu_calculate_dirtyrate(DIRTYLIMIT_CALC_TIME_MS,
+ vcpu_calculate_dirtyrate(period,
&stat,
GLOBAL_DIRTY_LIMIT,
false);
--
2.38.5
