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[PATCH QEMU v5 6/8] migration: Implement dirty-limit convergence algo
From: |
~hyman |
Subject: |
[PATCH QEMU v5 6/8] migration: Implement dirty-limit convergence algo |
Date: |
Thu, 08 Jun 2023 00:12:40 +0800 |
From: Hyman Huang(黄勇) <yong.huang@smartx.com>
Implement dirty-limit convergence algo for live migration,
which is kind of like auto-converge algo but using dirty-limit
instead of cpu throttle to make migration convergent.
Enable dirty page limit if dirty_rate_high_cnt greater than 2
when dirty-limit capability enabled, Disable dirty-limit if
migration be cancled.
Note that "set_vcpu_dirty_limit", "cancel_vcpu_dirty_limit"
commands are not allowed during dirty-limit live migration.
Signed-off-by: Hyman Huang(黄勇) <yong.huang@smartx.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
migration/migration.c | 3 ++
migration/ram.c | 63 ++++++++++++++++++++++++++++++++----------
migration/trace-events | 1 +
softmmu/dirtylimit.c | 22 +++++++++++++++
4 files changed, 74 insertions(+), 15 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index dc05c6f6ea..4278b48af0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -165,6 +165,9 @@ void migration_cancel(const Error *error)
if (error) {
migrate_set_error(current_migration, error);
}
+ if (migrate_dirty_limit()) {
+ qmp_cancel_vcpu_dirty_limit(false, -1, NULL);
+ }
migrate_fd_cancel(current_migration);
}
diff --git a/migration/ram.c b/migration/ram.c
index 132f1a81d9..d26c7a8193 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -46,6 +46,7 @@
#include "qapi/error.h"
#include "qapi/qapi-types-migration.h"
#include "qapi/qapi-events-migration.h"
+#include "qapi/qapi-commands-migration.h"
#include "qapi/qmp/qerror.h"
#include "trace.h"
#include "exec/ram_addr.h"
@@ -59,6 +60,8 @@
#include "multifd.h"
#include "sysemu/runstate.h"
#include "options.h"
+#include "sysemu/dirtylimit.h"
+#include "sysemu/kvm.h"
#include "hw/boards.h" /* for machine_dump_guest_core() */
@@ -983,6 +986,30 @@ static void migration_update_rates(RAMState *rs, int64_t
end_time)
}
}
+/*
+ * Enable dirty-limit to throttle down the guest
+ */
+static void migration_dirty_limit_guest(void)
+{
+ static int64_t quota_dirtyrate;
+ MigrationState *s = migrate_get_current();
+
+ /*
+ * If dirty limit already enabled and migration parameter
+ * vcpu-dirty-limit untouched.
+ */
+ if (dirtylimit_in_service() &&
+ quota_dirtyrate == s->parameters.vcpu_dirty_limit) {
+ return;
+ }
+
+ quota_dirtyrate = s->parameters.vcpu_dirty_limit;
+
+ /* Set or update quota dirty limit */
+ qmp_set_vcpu_dirty_limit(false, -1, quota_dirtyrate, NULL);
+ trace_migration_dirty_limit_guest(quota_dirtyrate);
+}
+
static void migration_trigger_throttle(RAMState *rs)
{
uint64_t threshold = migrate_throttle_trigger_threshold();
@@ -991,26 +1018,32 @@ static void migration_trigger_throttle(RAMState *rs)
uint64_t bytes_dirty_period = rs->num_dirty_pages_period *
TARGET_PAGE_SIZE;
uint64_t bytes_dirty_threshold = bytes_xfer_period * threshold / 100;
- /* During block migration the auto-converge logic incorrectly detects
- * that ram migration makes no progress. Avoid this by disabling the
- * throttling logic during the bulk phase of block migration. */
- if (blk_mig_bulk_active()) {
- return;
- }
+ /*
+ * The following detection logic can be refined later. For now:
+ * Check to see if the ratio between dirtied bytes and the approx.
+ * amount of bytes that just got transferred since the last time
+ * we were in this routine reaches the threshold. If that happens
+ * twice, start or increase throttling.
+ */
- if (migrate_auto_converge()) {
- /* The following detection logic can be refined later. For now:
- Check to see if the ratio between dirtied bytes and the approx.
- amount of bytes that just got transferred since the last time
- we were in this routine reaches the threshold. If that happens
- twice, start or increase throttling. */
+ if ((bytes_dirty_period > bytes_dirty_threshold) &&
+ (++rs->dirty_rate_high_cnt >= 2)) {
+ rs->dirty_rate_high_cnt = 0;
+ /*
+ * During block migration the auto-converge logic incorrectly detects
+ * that ram migration makes no progress. Avoid this by disabling the
+ * throttling logic during the bulk phase of block migration
+ */
+ if (blk_mig_bulk_active()) {
+ return;
+ }
- if ((bytes_dirty_period > bytes_dirty_threshold) &&
- (++rs->dirty_rate_high_cnt >= 2)) {
+ if (migrate_auto_converge()) {
trace_migration_throttle();
- rs->dirty_rate_high_cnt = 0;
mig_throttle_guest_down(bytes_dirty_period,
bytes_dirty_threshold);
+ } else if (migrate_dirty_limit()) {
+ migration_dirty_limit_guest();
}
}
}
diff --git a/migration/trace-events b/migration/trace-events
index cdaef7a1ea..c5cb280d95 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -91,6 +91,7 @@ migration_bitmap_sync_start(void) ""
migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64
migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size,
unsigned long page) "rb %s start 0x%"PRIx64" size 0x%"PRIx64" page 0x%lx"
migration_throttle(void) ""
+migration_dirty_limit_guest(int64_t dirtyrate) "guest dirty page rate limit %"
PRIi64 " MB/s"
ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start:
%" PRIx64 " %zx"
ram_load_loop(const char *rbname, uint64_t addr, int flags, void *host) "%s:
addr: 0x%" PRIx64 " flags: 0x%x host: %p"
ram_load_postcopy_loop(int channel, uint64_t addr, int flags) "chan=%d
addr=0x%" PRIx64 " flags=0x%x"
diff --git a/softmmu/dirtylimit.c b/softmmu/dirtylimit.c
index 3f1103b04b..ee47158986 100644
--- a/softmmu/dirtylimit.c
+++ b/softmmu/dirtylimit.c
@@ -440,6 +440,8 @@ void qmp_cancel_vcpu_dirty_limit(bool has_cpu_index,
int64_t cpu_index,
Error **errp)
{
+ MigrationState *ms = migrate_get_current();
+
if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
return;
}
@@ -453,6 +455,15 @@ void qmp_cancel_vcpu_dirty_limit(bool has_cpu_index,
return;
}
+ if (migration_is_running(ms->state) &&
+ (!qemu_thread_is_self(&ms->thread)) &&
+ migrate_dirty_limit() &&
+ dirtylimit_in_service()) {
+ error_setg(errp, "can't cancel dirty page limit while"
+ " migration is running");
+ return;
+ }
+
dirtylimit_state_lock();
if (has_cpu_index) {
@@ -488,6 +499,8 @@ void qmp_set_vcpu_dirty_limit(bool has_cpu_index,
uint64_t dirty_rate,
Error **errp)
{
+ MigrationState *ms = migrate_get_current();
+
if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
error_setg(errp, "dirty page limit feature requires KVM with"
" accelerator property 'dirty-ring-size' set'");
@@ -504,6 +517,15 @@ void qmp_set_vcpu_dirty_limit(bool has_cpu_index,
return;
}
+ if (migration_is_running(ms->state) &&
+ (!qemu_thread_is_self(&ms->thread)) &&
+ migrate_dirty_limit() &&
+ dirtylimit_in_service()) {
+ error_setg(errp, "can't cancel dirty page limit while"
+ " migration is running");
+ return;
+ }
+
dirtylimit_state_lock();
if (!dirtylimit_in_service()) {
--
2.38.5
- Re: [PATCH QEMU v5 2/8] qapi/migration: Introduce x-vcpu-dirty-limit-period parameter, (continued)