[RFC 1/3] cpu-throttle: new module, extracted from cpus.c

[Claudio Fontana]

this is a first step in the refactoring of cpus.c.

Signed-off-by: Claudio Fontana <address@hidden>
---
 MAINTAINERS                   |   1 +
 Makefile.target               |   8 ++-
 cpu-throttle.c                | 122 ++++++++++++++++++++++++++++++++++++++++++
 cpus.c                        |  95 +++-----------------------------
 include/hw/core/cpu.h         |  37 -------------
 include/qemu/main-loop.h      |   5 ++
 include/sysemu/cpu-throttle.h |  50 +++++++++++++++++
 migration/migration.c         |   1 +
 migration/ram.c               |   1 +
 9 files changed, 195 insertions(+), 125 deletions(-)
 create mode 100644 cpu-throttle.c
 create mode 100644 include/sysemu/cpu-throttle.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 87a412c229..35864a275a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2142,6 +2142,7 @@ Main loop
 M: Paolo Bonzini <address@hidden>
 S: Maintained
 F: cpus.c
+F: cpu-throttle.c
 F: include/qemu/main-loop.h
 F: include/sysemu/runstate.h
 F: util/main-loop.c
diff --git a/Makefile.target b/Makefile.target
index 8ed1eba95b..60cfa2a78b 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -152,7 +152,13 @@ endif #CONFIG_BSD_USER
 #########################################################
 # System emulator target
 ifdef CONFIG_SOFTMMU
-obj-y += arch_init.o cpus.o gdbstub.o balloon.o ioport.o
+obj-y += arch_init.o
+obj-y += cpus.o
+obj-y += cpu-throttle.o
+obj-y += gdbstub.o
+obj-y += balloon.o
+obj-y += ioport.o
+
 obj-y += qtest.o
 obj-y += dump/
 obj-y += hw/
diff --git a/cpu-throttle.c b/cpu-throttle.c
new file mode 100644
index 0000000000..4e6b2818ca
--- /dev/null
+++ b/cpu-throttle.c
@@ -0,0 +1,122 @@
+/*
+ * QEMU System Emulator
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to 
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu/thread.h"
+#include "hw/core/cpu.h"
+#include "qemu/main-loop.h"
+#include "sysemu/cpus.h"
+#include "sysemu/cpu-throttle.h"
+
+/* vcpu throttling controls */
+static QEMUTimer *throttle_timer;
+static unsigned int throttle_percentage;
+
+#define CPU_THROTTLE_PCT_MIN 1
+#define CPU_THROTTLE_PCT_MAX 99
+#define CPU_THROTTLE_TIMESLICE_NS 10000000
+
+static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque)
+{
+    double pct;
+    double throttle_ratio;
+    int64_t sleeptime_ns, endtime_ns;
+
+    if (!cpu_throttle_get_percentage()) {
+        return;
+    }
+
+    pct = (double)cpu_throttle_get_percentage() / 100;
+    throttle_ratio = pct / (1 - pct);
+    /* Add 1ns to fix double's rounding error (like 0.9999999...) */
+    sleeptime_ns = (int64_t)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS + 1);
+    endtime_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + sleeptime_ns;
+    while (sleeptime_ns > 0 && !cpu->stop) {
+        if (sleeptime_ns > SCALE_MS) {
+            qemu_cond_timedwait_iothread(cpu->halt_cond,
+                                         sleeptime_ns / SCALE_MS);
+        } else {
+            qemu_mutex_unlock_iothread();
+            g_usleep(sleeptime_ns / SCALE_US);
+            qemu_mutex_lock_iothread();
+        }
+        sleeptime_ns = endtime_ns - qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+    }
+    atomic_set(&cpu->throttle_thread_scheduled, 0);
+}
+
+static void cpu_throttle_timer_tick(void *opaque)
+{
+    CPUState *cpu;
+    double pct;
+
+    /* Stop the timer if needed */
+    if (!cpu_throttle_get_percentage()) {
+        return;
+    }
+    CPU_FOREACH(cpu) {
+        if (!atomic_xchg(&cpu->throttle_thread_scheduled, 1)) {
+            async_run_on_cpu(cpu, cpu_throttle_thread,
+                             RUN_ON_CPU_NULL);
+        }
+    }
+
+    pct = (double)cpu_throttle_get_percentage() / 100;
+    timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) +
+                                   CPU_THROTTLE_TIMESLICE_NS / (1 - pct));
+}
+
+void cpu_throttle_set(int new_throttle_pct)
+{
+    /* Ensure throttle percentage is within valid range */
+    new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX);
+    new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN);
+
+    atomic_set(&throttle_percentage, new_throttle_pct);
+
+    timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) +
+                                       CPU_THROTTLE_TIMESLICE_NS);
+}
+
+void cpu_throttle_stop(void)
+{
+    atomic_set(&throttle_percentage, 0);
+}
+
+bool cpu_throttle_active(void)
+{
+    return (cpu_throttle_get_percentage() != 0);
+}
+
+int cpu_throttle_get_percentage(void)
+{
+    return atomic_read(&throttle_percentage);
+}
+
+void cpu_throttle_init(void)
+{
+    throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
+                                  cpu_throttle_timer_tick, NULL);
+}
diff --git a/cpus.c b/cpus.c
index 5670c96bcf..3a46a4fc2b 100644
--- a/cpus.c
+++ b/cpus.c
@@ -61,6 +61,8 @@
 #include "hw/boards.h"
 #include "hw/hw.h"
 
+#include "sysemu/cpu-throttle.h"
+
 #ifdef CONFIG_LINUX
 
 #include <sys/prctl.h>
@@ -84,14 +86,6 @@ static QemuMutex qemu_global_mutex;
 int64_t max_delay;
 int64_t max_advance;
 
-/* vcpu throttling controls */
-static QEMUTimer *throttle_timer;
-static unsigned int throttle_percentage;
-
-#define CPU_THROTTLE_PCT_MIN 1
-#define CPU_THROTTLE_PCT_MAX 99
-#define CPU_THROTTLE_TIMESLICE_NS 10000000
-
 bool cpu_is_stopped(CPUState *cpu)
 {
     return cpu->stopped || !runstate_is_running();
@@ -710,90 +704,12 @@ static const VMStateDescription vmstate_timers = {
     }
 };
 
-static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque)
-{
-    double pct;
-    double throttle_ratio;
-    int64_t sleeptime_ns, endtime_ns;
-
-    if (!cpu_throttle_get_percentage()) {
-        return;
-    }
-
-    pct = (double)cpu_throttle_get_percentage()/100;
-    throttle_ratio = pct / (1 - pct);
-    /* Add 1ns to fix double's rounding error (like 0.9999999...) */
-    sleeptime_ns = (int64_t)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS + 1);
-    endtime_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + sleeptime_ns;
-    while (sleeptime_ns > 0 && !cpu->stop) {
-        if (sleeptime_ns > SCALE_MS) {
-            qemu_cond_timedwait(cpu->halt_cond, &qemu_global_mutex,
-                                sleeptime_ns / SCALE_MS);
-        } else {
-            qemu_mutex_unlock_iothread();
-            g_usleep(sleeptime_ns / SCALE_US);
-            qemu_mutex_lock_iothread();
-        }
-        sleeptime_ns = endtime_ns - qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
-    }
-    atomic_set(&cpu->throttle_thread_scheduled, 0);
-}
-
-static void cpu_throttle_timer_tick(void *opaque)
-{
-    CPUState *cpu;
-    double pct;
-
-    /* Stop the timer if needed */
-    if (!cpu_throttle_get_percentage()) {
-        return;
-    }
-    CPU_FOREACH(cpu) {
-        if (!atomic_xchg(&cpu->throttle_thread_scheduled, 1)) {
-            async_run_on_cpu(cpu, cpu_throttle_thread,
-                             RUN_ON_CPU_NULL);
-        }
-    }
-
-    pct = (double)cpu_throttle_get_percentage()/100;
-    timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) +
-                                   CPU_THROTTLE_TIMESLICE_NS / (1-pct));
-}
-
-void cpu_throttle_set(int new_throttle_pct)
-{
-    /* Ensure throttle percentage is within valid range */
-    new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX);
-    new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN);
-
-    atomic_set(&throttle_percentage, new_throttle_pct);
-
-    timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) +
-                                       CPU_THROTTLE_TIMESLICE_NS);
-}
-
-void cpu_throttle_stop(void)
-{
-    atomic_set(&throttle_percentage, 0);
-}
-
-bool cpu_throttle_active(void)
-{
-    return (cpu_throttle_get_percentage() != 0);
-}
-
-int cpu_throttle_get_percentage(void)
-{
-    return atomic_read(&throttle_percentage);
-}
-
 void cpu_ticks_init(void)
 {
     seqlock_init(&timers_state.vm_clock_seqlock);
     qemu_spin_init(&timers_state.vm_clock_lock);
     vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
-    throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
-                                           cpu_throttle_timer_tick, NULL);
+    cpu_throttle_init();
 }
 
 void configure_icount(QemuOpts *opts, Error **errp)
@@ -1852,6 +1768,11 @@ void qemu_cond_wait_iothread(QemuCond *cond)
     qemu_cond_wait(cond, &qemu_global_mutex);
 }
 
+void qemu_cond_timedwait_iothread(QemuCond *cond, int ms)
+{
+    qemu_cond_timedwait(cond, &qemu_global_mutex, ms);
+}
+
 static bool all_vcpus_paused(void)
 {
     CPUState *cpu;
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 07f7698155..e6b75d456c 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -817,43 +817,6 @@ bool cpu_exists(int64_t id);
  */
 CPUState *cpu_by_arch_id(int64_t id);
 
-/**
- * cpu_throttle_set:
- * @new_throttle_pct: Percent of sleep time. Valid range is 1 to 99.
- *
- * Throttles all vcpus by forcing them to sleep for the given percentage of
- * time. A throttle_percentage of 25 corresponds to a 75% duty cycle roughly.
- * (example: 10ms sleep for every 30ms awake).
- *
- * cpu_throttle_set can be called as needed to adjust new_throttle_pct.
- * Once the throttling starts, it will remain in effect until cpu_throttle_stop
- * is called.
- */
-void cpu_throttle_set(int new_throttle_pct);
-
-/**
- * cpu_throttle_stop:
- *
- * Stops the vcpu throttling started by cpu_throttle_set.
- */
-void cpu_throttle_stop(void);
-
-/**
- * cpu_throttle_active:
- *
- * Returns: %true if the vcpus are currently being throttled, %false otherwise.
- */
-bool cpu_throttle_active(void);
-
-/**
- * cpu_throttle_get_percentage:
- *
- * Returns the vcpu throttle percentage. See cpu_throttle_set for details.
- *
- * Returns: The throttle percentage in range 1 to 99.
- */
-int cpu_throttle_get_percentage(void);
-
 #ifndef CONFIG_USER_ONLY
 
 typedef void (*CPUInterruptHandler)(CPUState *, int);
diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index a6d20b0719..2fa3d90ad6 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -263,6 +263,11 @@ int qemu_add_child_watch(pid_t pid);
  */
 bool qemu_mutex_iothread_locked(void);
 
+/*
+ * qemu_cond_timedwait_iothread: like the previous, but with timeout
+ */
+void qemu_cond_timedwait_iothread(QemuCond *cond, int ms);
+
 /**
  * qemu_mutex_lock_iothread: Lock the main loop mutex.
  *
diff --git a/include/sysemu/cpu-throttle.h b/include/sysemu/cpu-throttle.h
new file mode 100644
index 0000000000..22356502a5
--- /dev/null
+++ b/include/sysemu/cpu-throttle.h
@@ -0,0 +1,50 @@
+#ifndef SYSEMU_CPU_THROTTLE_H
+#define SYSEMU_CPU_THROTTLE_H
+
+#include "qemu/timer.h"
+
+/**
+ * cpu_throttle_init:
+ *
+ * Initialize the CPU throttling API.
+ */
+void cpu_throttle_init(void);
+
+/**
+ * cpu_throttle_set:
+ * @new_throttle_pct: Percent of sleep time. Valid range is 1 to 99.
+ *
+ * Throttles all vcpus by forcing them to sleep for the given percentage of
+ * time. A throttle_percentage of 25 corresponds to a 75% duty cycle roughly.
+ * (example: 10ms sleep for every 30ms awake).
+ *
+ * cpu_throttle_set can be called as needed to adjust new_throttle_pct.
+ * Once the throttling starts, it will remain in effect until cpu_throttle_stop
+ * is called.
+ */
+void cpu_throttle_set(int new_throttle_pct);
+
+/**
+ * cpu_throttle_stop:
+ *
+ * Stops the vcpu throttling started by cpu_throttle_set.
+ */
+void cpu_throttle_stop(void);
+
+/**
+ * cpu_throttle_active:
+ *
+ * Returns: %true if the vcpus are currently being throttled, %false otherwise.
+ */
+bool cpu_throttle_active(void);
+
+/**
+ * cpu_throttle_get_percentage:
+ *
+ * Returns the vcpu throttle percentage. See cpu_throttle_set for details.
+ *
+ * Returns: The throttle percentage in range 1 to 99.
+ */
+int cpu_throttle_get_percentage(void);
+
+#endif /* SYSEMU_CPU_THROTTLE_H */
diff --git a/migration/migration.c b/migration/migration.c
index 0bb042a0f7..dd18323f32 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -23,6 +23,7 @@
 #include "socket.h"
 #include "sysemu/runstate.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/cpu-throttle.h"
 #include "rdma.h"
 #include "ram.h"
 #include "migration/global_state.h"
diff --git a/migration/ram.c b/migration/ram.c
index 859f835f1a..527f0c7316 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -52,6 +52,7 @@
 #include "migration/colo.h"
 #include "block.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/cpu-throttle.h"
 #include "savevm.h"
 #include "qemu/iov.h"
 #include "multifd.h"
-- 
2.16.4