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[Qemu-devel] [PATCH v3 1/5] mc146818rtc: update periodic timer only if i
From: |
guangrong . xiao |
Subject: |
[Qemu-devel] [PATCH v3 1/5] mc146818rtc: update periodic timer only if it is needed |
Date: |
Wed, 10 May 2017 16:32:55 +0800 |
From: Xiao Guangrong <address@hidden>
Currently, the timer is updated whenever RegA or RegB is written
even if the periodic timer related configuration is not changed
This patch optimizes it slightly to make the update happen only
if its period or enable-status is changed, also later patches are
depend on this optimization
Signed-off-by: Xiao Guangrong <address@hidden>
---
hw/timer/mc146818rtc.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index 4165450..5cccb2a 100644
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -391,6 +391,7 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
uint64_t data, unsigned size)
{
RTCState *s = opaque;
+ bool update_periodic_timer;
if ((addr & 1) == 0) {
s->cmos_index = data & 0x7f;
@@ -423,6 +424,8 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
}
break;
case RTC_REG_A:
+ update_periodic_timer = (s->cmos_data[RTC_REG_A] ^ data) & 0x0f;
+
if ((data & 0x60) == 0x60) {
if (rtc_running(s)) {
rtc_update_time(s);
@@ -445,10 +448,17 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
/* UIP bit is read only */
s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |
(s->cmos_data[RTC_REG_A] & REG_A_UIP);
- periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
+
+ if (update_periodic_timer) {
+ periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
+ }
+
check_update_timer(s);
break;
case RTC_REG_B:
+ update_periodic_timer = (s->cmos_data[RTC_REG_B] ^ data)
+ & REG_B_PIE;
+
if (data & REG_B_SET) {
/* update cmos to when the rtc was stopping */
if (rtc_running(s)) {
@@ -475,7 +485,11 @@ static void cmos_ioport_write(void *opaque, hwaddr addr,
qemu_irq_lower(s->irq);
}
s->cmos_data[RTC_REG_B] = data;
- periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
+
+ if (update_periodic_timer) {
+ periodic_timer_update(s, qemu_clock_get_ns(rtc_clock));
+ }
+
check_update_timer(s);
break;
case RTC_REG_C:
--
2.9.3
- [Qemu-devel] [PATCH v3 0/5] mc146818rtc: fix Windows VM clock faster, guangrong . xiao, 2017/05/10
- [Qemu-devel] [PATCH v3 1/5] mc146818rtc: update periodic timer only if it is needed,
guangrong . xiao <=
- [Qemu-devel] [PATCH v3 2/5] mc146818rtc: precisely count the clock for periodic timer, guangrong . xiao, 2017/05/10
- [Qemu-devel] [PATCH v3 3/5] mc146818rtc: ensure LOST_TICK_POLICY_SLEW is only enabled on TARGET_I386, guangrong . xiao, 2017/05/10
- [Qemu-devel] [PATCH v3 4/5] mc146818rtc: drop unnecessary '#ifdef TARGET_I386', guangrong . xiao, 2017/05/10
- [Qemu-devel] [PATCH v3 5/5] mc146818rtc: embrace all x86 specific code, guangrong . xiao, 2017/05/10
- Re: [Qemu-devel] [PATCH v3 0/5] mc146818rtc: fix Windows VM clock faster, Paolo Bonzini, 2017/05/10