Add infrastructure to compute timed averages

index b890613..1c639d2 100644
@@ -27,8 +27,6 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 
-#define NANOSECONDS_PER_SECOND  1000000000.0
-
 typedef enum {
     THROTTLE_BPS_TOTAL,
     THROTTLE_BPS_READ,

index e5bd494..1f1e56b 100644
@@ -5,6 +5,8 @@
 #include "qemu-common.h"
 #include "qemu/notify.h"
 
+#define NANOSECONDS_PER_SECOND 1000000000LL
+
 /* timers */
 
 #define SCALE_MS 1000000

index 99db56c..2a4b8e1 100644
@@ -51,8 +51,6 @@
 #  define LOG_TB(...) do { } while (0)
 #endif
 
-#define NSEC_PER_SEC    1000000000LL
-
 static void cpu_ppc_tb_stop (CPUPPCState *env);
 static void cpu_ppc_tb_start (CPUPPCState *env);
 

index 83eb7c1..9da3746 100644
@@ -26,6 +26,7 @@
  *
  */
 #include "cpu.h"
+#include "qemu/timer.h"
 #include "sysemu/sysemu.h"
 #include "hw/ppc/spapr.h"
 #include "qapi-event.h"

@@ -40,8 +41,6 @@ struct sPAPRRTCState {
     int64_t ns_offset;
 };
 
-#define NSEC_PER_SEC    1000000000LL
-
 void spapr_rtc_read(DeviceState *dev, struct tm *tm, uint32_t *ns)
 {
     sPAPRRTCState *rtc = SPAPR_RTC(dev);

index f2b77fa..41563be 100644
@@ -48,7 +48,6 @@
 # define DPRINTF_C(format, ...)      do { } while (0)
 #endif
 
-#define NSEC_PER_SEC    1000000000LL
 #define SEC_PER_MIN     60
 #define MIN_PER_HOUR    60
 #define SEC_PER_HOUR    3600

index d4d7547..d7cd40b 100644
@@ -32,7 +32,7 @@
 #include "trace.h"
 
 #define FRAME_TIMER_FREQ 1000
-#define FRAME_TIMER_NS   (1000000000 / FRAME_TIMER_FREQ)
+#define FRAME_TIMER_NS   (NSEC_PER_SEC / FRAME_TIMER_FREQ)
 #define UFRAME_TIMER_NS  (FRAME_TIMER_NS / 8)
 
 #define NB_MAXINTRATE    8        // Max rate at which controller issues ints

index 1f1e56b..72a2529 100644
@@ -5,7 +5,7 @@
 #include "qemu-common.h"
 #include "qemu/notify.h"
 
-#define NANOSECONDS_PER_SECOND 1000000000LL
+#define NSEC_PER_SEC 1000000000LL
 
 /* timers */
 

index 4e0bf02..3bff0e3 100644
@@ -12,6 +12,7 @@
 #include "libqtest.h"
 #include "libqos/pci-pc.h"
 #include "qemu/osdep.h"
+#include "qemu/timer.h"
 #include "qemu-common.h"
 
 /* Tests only initialization so far. TODO: Replace with functional tests */

@@ -20,7 +21,6 @@ static void nop(void)
 }
 
 #define CLK 33000000
-#define NS_PER_SEC 1000000000ULL
 
 static QPCIBus *pcibus;
 static QPCIDevice *dev;

@@ -86,7 +86,7 @@ static void test_timer(void)
         fatal("time too big %u\n", curr);
     }
     for (cnt = 0; ; ) {
-        clock_step(1 * NS_PER_SEC);
+        clock_step(1 * NSEC_PER_SEC);
         prev = curr;
         curr = in_Timer();
 

@@ -125,7 +125,7 @@ static void test_timer(void)
     out_IntrStatus(0x4000);
     curr = in_Timer();
     out_TimerInt(curr + 0.5 * CLK);
-    clock_step(1 * NS_PER_SEC);
+    clock_step(1 * NSEC_PER_SEC);
     out_Timer(0);
     if ((in_IntrStatus() & 0x4000) == 0) {
         fatal("we should have an interrupt here!\n");

@@ -137,7 +137,7 @@ static void test_timer(void)
     out_IntrStatus(0x4000);
     curr = in_Timer();
     out_TimerInt(curr + 0.5 * CLK);
-    clock_step(1 * NS_PER_SEC);
+    clock_step(1 * NSEC_PER_SEC);
     out_TimerInt(0);
     if ((in_IntrStatus() & 0x4000) == 0) {
         fatal("we should have an interrupt here!\n");

@@ -148,7 +148,7 @@ static void test_timer(void)
     next = curr + 5.0 * CLK;
     out_TimerInt(next);
     for (cnt = 0; ; ) {
-        clock_step(1 * NS_PER_SEC);
+        clock_step(1 * NSEC_PER_SEC);
         prev = curr;
         curr = in_Timer();
         diff = (curr-prev) & 0xffffffffu;

index d8ba415..00e4c70 100644
@@ -36,19 +36,19 @@ static void test_leak_bucket(void)
     bkt.level = 1.5;
 
     /* leak an op work of time */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0.5));
 
     /* leak again emptying the bucket */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0));
 
     /* check that the bucket level won't go lower */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0));

@@ -86,7 +86,7 @@ static void test_compute_wait(void)
     bkt.level = 15.5;
     wait = throttle_compute_wait(&bkt);
     /* time required to do half an operation */
-    result = (int64_t)  NANOSECONDS_PER_SECOND / 150 / 2;
+    result = (int64_t)  NSEC_PER_SEC / 150 / 2;
     g_assert(wait == result);
 }
 

index 513a533..10a5472 100644
@@ -11,8 +11,7 @@
 #include <string.h>
 #include "libqtest.h"
 #include "qemu/osdep.h"
-
-#define NS_PER_SEC 1000000000ULL
+#include "qemu/timer.h"
 
 static void qmp_check_no_event(void)
 {

@@ -41,29 +40,29 @@ static QDict *qmp_get_event(const char *name)
 
 static QDict *ib700_program_and_wait(QTestState *s)
 {
-    clock_step(NS_PER_SEC * 40);
+    clock_step(NSEC_PER_SEC * 40);
     qmp_check_no_event();
 
     /* 2 second limit */
     outb(0x443, 14);
 
     /* Ping */
-    clock_step(NS_PER_SEC);
+    clock_step(NSEC_PER_SEC);
     qmp_check_no_event();
     outb(0x443, 14);
 
     /* Disable */
-    clock_step(NS_PER_SEC);
+    clock_step(NSEC_PER_SEC);
     qmp_check_no_event();
     outb(0x441, 1);
-    clock_step(3 * NS_PER_SEC);
+    clock_step(3 * NSEC_PER_SEC);
     qmp_check_no_event();
 
     /* Enable and let it fire */
     outb(0x443, 13);
-    clock_step(3 * NS_PER_SEC);
+    clock_step(3 * NSEC_PER_SEC);
     qmp_check_no_event();
-    clock_step(2 * NS_PER_SEC);
+    clock_step(2 * NSEC_PER_SEC);
     return qmp_get_event("WATCHDOG");
 }
 

index f976ac7..7678027 100644
@@ -34,7 +34,7 @@ void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta_ns)
     double leak;
 
     /* compute how much to leak */
-    leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
+    leak = (bkt->avg * (double) delta_ns) / NSEC_PER_SEC;
 
     /* make the bucket leak */
     bkt->level = MAX(bkt->level - leak, 0);

@@ -70,7 +70,7 @@ static void throttle_do_leak(ThrottleState *ts, int64_t now)
  */
 static int64_t throttle_do_compute_wait(double limit, double extra)
 {
-    double wait = extra * NANOSECONDS_PER_SECOND;
+    double wait = extra * NSEC_PER_SEC;
     wait /= limit;
     return wait;
 }

new file mode 100644
index 0000000..b9532e6
@@ -0,0 +1,58 @@
+/*
+ * QEMU timed average computation
+ *
+ * Copyright (C) Nodalink, EURL. 2014
+ * Copyright (C) Igalia, S.L. 2015
+ *
+ * Authors:
+ *   Benoît Canet <[email protected]>
+ *   Alberto Garcia <[email protected]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) version 3 or any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TIMED_AVERAGE_H
+#define TIMED_AVERAGE_H
+
+#include <stdint.h>
+
+#include "qemu/timer.h"
+
+typedef struct TimedAverageWindow {
+    uint64_t      min;             /* minimum value accounted in the window */
+    uint64_t      max;             /* maximum value accounted in the window */
+    uint64_t      sum;             /* sum of all values */
+    uint64_t      count;           /* number of values */
+    int64_t       expiration;      /* the end of the current window in ns */
+} TimedAverageWindow;
+
+typedef struct TimedAverage {
+    uint64_t           period;     /* period in nanoseconds */
+    TimedAverageWindow windows[2]; /* two overlapping windows of with
+                                    * an offset of period / 2 between them */
+    unsigned           current;    /* the current window index: it's also the
+                                    * oldest window index */
+    QEMUClockType      clock_type; /* the clock used */
+} TimedAverage;
+
+void timed_average_init(TimedAverage *ta, QEMUClockType clock_type,
+                        unsigned period);
+
+void timed_average_account(TimedAverage *ta, uint64_t value);
+
+uint64_t timed_average_min(TimedAverage *ta);
+uint64_t timed_average_avg(TimedAverage *ta);
+uint64_t timed_average_max(TimedAverage *ta);
+
+#endif

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