Hi,
On 20/11/22 23:54, Shivam Kumar wrote:
Introduces a (new) throttling scheme where QEMU defines a limit on the dirty
rate of each vcpu of the VM. This limit is enfored on the vcpus in small
intervals (dirty quota intervals) by allowing the vcpus to dirty only as many
pages in these intervals as to maintain a dirty rate below the set limit.
Suggested-by: Shaju Abraham <shaju.abraham@xxxxxxxxxxx>
Suggested-by: Manish Mishra <manish.mishra@xxxxxxxxxxx>
Co-developed-by: Anurag Madnawat <anurag.madnawat@xxxxxxxxxxx>
Signed-off-by: Anurag Madnawat <anurag.madnawat@xxxxxxxxxxx>
Signed-off-by: Shivam Kumar <shivam.kumar1@xxxxxxxxxxx>
---
accel/kvm/kvm-all.c | 91 +++++++++++++++++++++++++++++++++++++++
include/exec/memory.h | 3 ++
include/hw/core/cpu.h | 5 +++
include/sysemu/kvm_int.h | 1 +
linux-headers/linux/kvm.h | 9 ++++
migration/migration.c | 22 ++++++++++
migration/migration.h | 31 +++++++++++++
softmmu/memory.c | 64 +++++++++++++++++++++++++++
8 files changed, 226 insertions(+)
void migrate_set_state(int *state, int old_state, int new_state);
diff --git a/softmmu/memory.c b/softmmu/memory.c
index bc0be3f62c..8f725a9b89 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -12,6 +12,7 @@
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
+#include <linux/kvm.h>
#include "qemu/osdep.h"
#include "qemu/log.h"
@@ -34,6 +35,10 @@
#include "hw/boards.h"
#include "migration/vmstate.h"
#include "exec/address-spaces.h"
+#include "hw/core/cpu.h"
+#include "exec/target_page.h"
+#include "migration/migration.h"
+#include "sysemu/kvm_int.h"
//#define DEBUG_UNASSIGNED
@@ -2869,6 +2874,46 @@ static unsigned int postponed_stop_flags;
static VMChangeStateEntry *vmstate_change;
static void memory_global_dirty_log_stop_postponed_run(void);
+static void init_vcpu_dirty_quota(CPUState *cpu, run_on_cpu_data arg)
+{
+ uint64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+ cpu->kvm_run->dirty_quota = 1;
+ cpu->dirty_quota_expiry_time = current_time;
+}
+
+void dirty_quota_migration_start(void)
+{
+ if (!kvm_state->dirty_quota_supported) {
You are accessing an accelerator-specific variable in an
accelerator-agnostic file, this doesn't sound correct.
You might introduce some hooks in AccelClass and implement them in
accel/kvm/. See for example gdbstub_supported_sstep_flags() and
kvm_gdbstub_sstep_flags().
+ return;
+ }
+
+ MigrationState *s = migrate_get_current();
+ /* Assuming initial bandwidth to be 128 MBps. */
+ double pages_per_second = (((double) 1e9) / 8.0) /
+ (double) qemu_target_page_size();
+ uint32_t nr_cpus;
+ CPUState *cpu;
+
+ CPU_FOREACH(cpu) {
+ nr_cpus++;
+ }
+ /*
+ * Currently we are hardcoding this to 2. There are plans to allow the user
+ * to manually select this ratio.
+ */
+ s->dirty_quota_throttle_ratio = 2;
+ qatomic_set(&s->per_vcpu_dirty_rate_limit,
+ pages_per_second / s->dirty_quota_throttle_ratio / nr_cpus);
+
+ qemu_spin_lock(&s->common_dirty_quota_lock);
+ s->common_dirty_quota = 0;
+ qemu_spin_unlock(&s->common_dirty_quota_lock);
+
+ CPU_FOREACH(cpu) {
+ run_on_cpu(cpu, init_vcpu_dirty_quota, RUN_ON_CPU_NULL);
+ }
+}
+
void memory_global_dirty_log_start(unsigned int flags)
{
unsigned int old_flags;
@@ -2891,6 +2936,7 @@ void memory_global_dirty_log_start(unsigned int flags)
trace_global_dirty_changed(global_dirty_tracking);
if (!old_flags) {
+ dirty_quota_migration_start();
MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
memory_region_transaction_begin();
memory_region_update_pending = true;
@@ -2898,6 +2944,23 @@ void memory_global_dirty_log_start(unsigned int flags)
}
}
+static void reset_vcpu_dirty_quota(CPUState *cpu, run_on_cpu_data arg)
+{
+ cpu->kvm_run->dirty_quota = 0;
+}
+
+void dirty_quota_migration_stop(void)
+{
+ if (!kvm_state->dirty_quota_supported) {
+ return;
+ }
+
+ CPUState *cpu;
+ CPU_FOREACH(cpu) {
+ run_on_cpu(cpu, reset_vcpu_dirty_quota, RUN_ON_CPU_NULL);
+ }
+}
+
static void memory_global_dirty_log_do_stop(unsigned int flags)
{
assert(flags && !(flags & (~GLOBAL_DIRTY_MASK)));
@@ -2907,6 +2970,7 @@ static void memory_global_dirty_log_do_stop(unsigned int flags)
trace_global_dirty_changed(global_dirty_tracking);
if (!global_dirty_tracking) {
+ dirty_quota_migration_stop();
memory_region_transaction_begin();
memory_region_update_pending = true;
memory_region_transaction_commit();
