[PATCH v7 3/3] cpus-common: implement dirty page limit on vCPU

[huangy81]

From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

Implement dirtyrate calculation periodically basing on
dirty-ring and throttle vCPU until it reachs the quota
dirty page rate given by user.

Introduce qmp commands set-dirty-limit/cancel-dirty-limit to
set/cancel dirty page limit on vCPU.

Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
---
 cpus-common.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/core/cpu.h |  9 +++++++++
 qapi/migration.json   | 43 +++++++++++++++++++++++++++++++++++++++++++
 softmmu/vl.c          |  1 +
 4 files changed, 101 insertions(+)

diff --git a/cpus-common.c b/cpus-common.c
index 6e73d3e..86c7712 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -23,6 +23,11 @@
 #include "hw/core/cpu.h"
 #include "sysemu/cpus.h"
 #include "qemu/lockable.h"
+#include "sysemu/dirtylimit.h"
+#include "sysemu/cpu-throttle.h"
+#include "sysemu/kvm.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-migration.h"
 
 static QemuMutex qemu_cpu_list_lock;
 static QemuCond exclusive_cond;
@@ -352,3 +357,46 @@ void process_queued_cpu_work(CPUState *cpu)
     qemu_mutex_unlock(&cpu->work_mutex);
     qemu_cond_broadcast(&qemu_work_cond);
 }
+
+void qmp_set_dirty_limit(int64_t idx,
+                         uint64_t dirtyrate,
+                         Error **errp)
+{
+    if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
+        error_setg(errp, "setting a dirty page limit requires KVM with"
+                   " accelerator property 'dirty-ring-size' set'");
+        return;
+    }
+
+    dirtylimit_calc();
+    dirtylimit_vcpu(idx, dirtyrate);
+}
+
+void qmp_cancel_dirty_limit(int64_t idx,
+                            Error **errp)
+{
+    if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
+        error_setg(errp, "KVM with accelerator property 'dirty-ring-size'"
+                   " not set, abort canceling a dirty page limit");
+        return;
+    }
+
+    if (!dirtylimit_enabled(idx)) {
+        error_setg(errp, "dirty page limit for the CPU %ld not set", idx);
+        return;
+    }
+
+    if (unlikely(!dirtylimit_cancel_vcpu(idx))) {
+        dirtylimit_calc_quit();
+    }
+}
+
+void dirtylimit_setup(int max_cpus)
+{
+    if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
+        return;
+    }
+
+    dirtylimit_calc_state_init(max_cpus);
+    dirtylimit_state_init(max_cpus);
+}
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index e948e81..11df012 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -881,6 +881,15 @@ void end_exclusive(void);
  */
 void qemu_init_vcpu(CPUState *cpu);
 
+/**
+ * dirtylimit_setup:
+ *
+ * Initializes the global state of dirtylimit calculation and
+ * dirtylimit itself. This is prepared for vCPU dirtylimit which
+ * could be triggered during vm lifecycle.
+ */
+void dirtylimit_setup(int max_cpus);
+
 #define SSTEP_ENABLE  0x1  /* Enable simulated HW single stepping */
 #define SSTEP_NOIRQ   0x2  /* Do not use IRQ while single stepping */
 #define SSTEP_NOTIMER 0x4  /* Do not Timers while single stepping */
diff --git a/qapi/migration.json b/qapi/migration.json
index bbfd48c..57c9a63 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1850,6 +1850,49 @@
 { 'command': 'query-dirty-rate', 'returns': 'DirtyRateInfo' }
 
 ##
+# @set-dirty-limit:
+#
+# Set the upper limit of dirty page rate for a virtual CPU.
+#
+# Requires KVM with accelerator property "dirty-ring-size" set.
+# A virtual CPU's dirty page rate is a measure of its memory load.
+# To observe dirty page rates, use @calc-dirty-rate.
+#
+# @cpu-index: index of the virtual CPU.
+#
+# @dirty-rate: upper limit for the specified vCPU's dirty page rate (MB/s)
+#
+# Since: 7.0
+#
+# Example:
+#   {"execute": "set-dirty-limit"}
+#    "arguments": { "cpu-index": 0,
+#                   "dirty-rate": 200 } }
+#
+##
+{ 'command': 'set-dirty-limit',
+  'data': { 'cpu-index': 'int', 'dirty-rate': 'uint64' } }
+
+##
+# @cancel-dirty-limit:
+#
+# Cancel the dirty page limit for the vCPU which has been set with
+# set-dirty-limit command. Note that this command requires support from
+# dirty ring, same as the "set-dirty-limit" command.
+#
+# @cpu-index: index of the virtual CPU to cancel the dirty page limit
+#
+# Since: 7.0
+#
+# Example:
+#   {"execute": "cancel-dirty-limit"}
+#    "arguments": { "cpu-index": 0 } }
+#
+##
+{ 'command': 'cancel-dirty-limit',
+  'data': { 'cpu-index': 'int' } }
+
+##
 # @snapshot-save:
 #
 # Save a VM snapshot
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 620a1f1..0f83ce3 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -3777,5 +3777,6 @@ void qemu_init(int argc, char **argv, char **envp)
     qemu_init_displays();
     accel_setup_post(current_machine);
     os_setup_post();
+    dirtylimit_setup(current_machine->smp.max_cpus);
     resume_mux_open();
 }
-- 
1.8.3.1