diff mbox series

[v1,3/5] kvm: Dirty ring autoconverge optmization for kvm_cpu_synchronize_kick_all

Message ID f9637c2b11d1fbafece205c5276564fb390bcc0b.1648002360.git.wucy11@chinatelecom.cn
State New
Headers show
Series Dirty ring and auto converge optimization | expand

Commit Message

Chongyun Wu March 23, 2022, 3:18 a.m. UTC 
From: Chongyun Wu <wucy11@chinatelecom.cn>

Dirty ring feature need call kvm_cpu_synchronize_kick_all
to flush hardware buffers into KVMslots, but when aucoverge
run kvm_cpu_synchronize_kick_all calling will become more
and more time consuming. This will significantly reduce the
efficiency of dirty page queries, especially when memory
pressure is high and the speed limit is high.

When the CPU speed limit is high and kvm_cpu_synchronize_kick_all
is time-consuming, the rate of dirty pages generated by the VM
will also be significantly reduced, so it is not necessary to
call kvm_cpu_synchronize_kick_all at this time, just call it once
before stopping the VM. This will significantly improve the
efficiency of dirty page queries under high pressure.

Signed-off-by: Chongyun Wu <wucy11@chinatelecom.cn>
---
 accel/kvm/kvm-all.c       | 25 +++++--------------------
 include/exec/cpu-common.h |  2 ++
 migration/migration.c     | 11 +++++++++++
 softmmu/cpus.c            | 18 ++++++++++++++++++
 4 files changed, 36 insertions(+), 20 deletions(-)
diff mbox series

Patch

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 65a4de8..5e02700 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -48,6 +48,8 @@ 
 
 #include "hw/boards.h"
 
+#include "sysemu/cpu-throttle.h"
+
 /* This check must be after config-host.h is included */
 #ifdef CONFIG_EVENTFD
 #include <sys/eventfd.h>
@@ -839,25 +841,6 @@  static uint64_t kvm_dirty_ring_reap(KVMState *s)
     return total;
 }
 
-static void do_kvm_cpu_synchronize_kick(CPUState *cpu, run_on_cpu_data arg)
-{
-    /* No need to do anything */
-}
-
-/*
- * Kick all vcpus out in a synchronized way.  When returned, we
- * guarantee that every vcpu has been kicked and at least returned to
- * userspace once.
- */
-static void kvm_cpu_synchronize_kick_all(void)
-{
-    CPUState *cpu;
-
-    CPU_FOREACH(cpu) {
-        run_on_cpu(cpu, do_kvm_cpu_synchronize_kick, RUN_ON_CPU_NULL);
-    }
-}
-
 /*
  * Flush all the existing dirty pages to the KVM slot buffers.  When
  * this call returns, we guarantee that all the touched dirty pages
@@ -879,7 +862,9 @@  static void kvm_dirty_ring_flush(void)
      * First make sure to flush the hardware buffers by kicking all
      * vcpus out in a synchronous way.
      */
-    kvm_cpu_synchronize_kick_all();
+    if (!cpu_throttle_get_percentage()) {
+        qemu_kvm_cpu_synchronize_kick_all();
+    }
     kvm_dirty_ring_reap(kvm_state);
     trace_kvm_dirty_ring_flush(1);
 }
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 50a7d29..13045b3 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -160,4 +160,6 @@  extern int singlestep;
 
 void list_cpus(const char *optarg);
 
+void qemu_kvm_cpu_synchronize_kick_all(void);
+
 #endif /* CPU_COMMON_H */
diff --git a/migration/migration.c b/migration/migration.c
index 695f0f2..ca1db88 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -61,6 +61,7 @@ 
 #include "sysemu/cpus.h"
 #include "yank_functions.h"
 #include "sysemu/qtest.h"
+#include "sysemu/kvm.h"
 
 #define MAX_THROTTLE  (128 << 20)      /* Migration transfer speed throttling */
 
@@ -3183,6 +3184,16 @@  static void migration_completion(MigrationState *s)
 
         if (!ret) {
             bool inactivate = !migrate_colo_enabled();
+            /*
+             * Before stop vm do qemu_kvm_cpu_synchronize_kick_all to
+             * fulsh hardware buffer into KVMslots for dirty ring
+             * optmiaztion, If qemu_kvm_cpu_synchronize_kick_all is not
+             * called when the CPU speed is limited to improve efficiency
+             */
+            if (kvm_dirty_ring_enabled()
+                && cpu_throttle_get_percentage()) {
+                qemu_kvm_cpu_synchronize_kick_all();
+            }
             ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
             trace_migration_completion_vm_stop(ret);
             if (ret >= 0) {
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 7b75bb6..d028d83 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -810,3 +810,21 @@  void qmp_inject_nmi(Error **errp)
     nmi_monitor_handle(monitor_get_cpu_index(monitor_cur()), errp);
 }
 
+static void do_kvm_cpu_synchronize_kick(CPUState *cpu, run_on_cpu_data arg)
+{
+    /* No need to do anything */
+}
+
+/*
+ * Kick all vcpus out in a synchronized way.  When returned, we
+ * guarantee that every vcpu has been kicked and at least returned to
+ * userspace once.
+ */
+void qemu_kvm_cpu_synchronize_kick_all(void)
+{
+    CPUState *cpu;
+
+    CPU_FOREACH(cpu) {
+        run_on_cpu(cpu, do_kvm_cpu_synchronize_kick, RUN_ON_CPU_NULL);
+    }
+}