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[Qemu-devel] [PATCH 2/3] Fix time drift problem under high load when PIT
From: |
Gleb Natapov |
Subject: |
[Qemu-devel] [PATCH 2/3] Fix time drift problem under high load when PIT is in use. |
Date: |
Sun, 29 Jun 2008 17:02:25 +0300 |
User-agent: |
StGIT/0.14.2 |
Count the number of interrupts that was lost due to interrupt coalescing
and re-inject them back when possible. This fixes time drift problem when
pit is used as a time source.
Signed-off-by: Gleb Natapov <address@hidden>
---
hw/i8254.c | 20 +++++++++++++++++++-
1 files changed, 19 insertions(+), 1 deletions(-)
diff --git a/hw/i8254.c b/hw/i8254.c
index 4813b03..c4f0f46 100644
--- a/hw/i8254.c
+++ b/hw/i8254.c
@@ -61,6 +61,8 @@ static PITState pit_state;
static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
+static uint32_t pit_irq_coalesced;
+
static int pit_get_count(PITChannelState *s)
{
uint64_t d;
@@ -369,12 +371,28 @@ static void pit_irq_timer_update(PITChannelState *s,
int64_t current_time)
return;
expire_time = pit_get_next_transition_time(s, current_time);
irq_level = pit_get_out1(s, current_time);
- qemu_set_irq(s->irq, irq_level);
+ if(irq_level) {
+ if(!qemu_irq_raise(s->irq))
+ pit_irq_coalesced++;
+ } else {
+ qemu_irq_lower(s->irq);
+ if(pit_irq_coalesced > 0) {
+ if(qemu_irq_raise(s->irq))
+ pit_irq_coalesced--;
+ qemu_irq_lower(s->irq);
+ }
+ }
+
#ifdef DEBUG_PIT
printf("irq_level=%d next_delay=%f\n",
irq_level,
(double)(expire_time - current_time) / ticks_per_sec);
#endif
+ if(pit_irq_coalesced && expire_time != -1) {
+ uint32_t div = ((pit_irq_coalesced >> 10) & 0x7f) + 2;
+ expire_time -= ((expire_time - current_time) / div);
+ }
+
s->next_transition_time = expire_time;
if (expire_time != -1)
qemu_mod_timer(s->irq_timer, expire_time);
- Re: [Qemu-devel] [PATCH 1/3] Change qemu_set_irq() to return status information., (continued)
- [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Jan Kiszka, 2008/06/29
- Re: [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Paul Brook, 2008/06/29
- Re: [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Dor Laor, 2008/06/29
- Re: [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Jan Kiszka, 2008/06/29
- Re: [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Paul Brook, 2008/06/29
- [Qemu-devel] Re: [PATCH 1/3] Change qemu_set_irq() to return status information., Gleb Natapov, 2008/06/30
[Qemu-devel] [PATCH 2/3] Fix time drift problem under high load when PIT is in use.,
Gleb Natapov <=
[Qemu-devel] [PATCH 3/3] Fix time drift problem under high load when RTC is in use., Gleb Natapov, 2008/06/29
[Qemu-devel] Re: [PATCH 0/3] Fix guest time drift under heavy load., Jan Kiszka, 2008/06/29