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[Qemu-devel] [PATCH 3/6] hw/char/pl011: don't keep setting the IRQ if no
From: |
Alex Bennée |
Subject: |
[Qemu-devel] [PATCH 3/6] hw/char/pl011: don't keep setting the IRQ if nothing changed |
Date: |
Wed, 25 Feb 2015 16:02:35 +0000 |
While observing KVM traces I can see additional IRQ calls on pretty much
every MMIO access which is just plain inefficient. Only update the QEMU
IRQ level if something has actually changed from last time. Otherwise we
may be papering over other failure modes.
Signed-off-by: Alex Bennée <address@hidden>
diff --git a/hw/char/pl011.c b/hw/char/pl011.c
index 0a45115..bb554bc 100644
--- a/hw/char/pl011.c
+++ b/hw/char/pl011.c
@@ -36,6 +36,9 @@ typedef struct PL011State {
CharDriverState *chr;
qemu_irq irq;
const unsigned char *id;
+
+ /* not serialised, prevents pl011_update doing extra set_irqs */
+ uint32_t current_irq;
} PL011State;
#define PL011_INT_TX 0x20
@@ -53,10 +56,11 @@ static const unsigned char pl011_id_luminary[8] =
static void pl011_update(PL011State *s)
{
- uint32_t flags;
-
- flags = s->int_level & s->int_enabled;
- qemu_set_irq(s->irq, flags != 0);
+ uint32_t flags = s->int_level & s->int_enabled;
+ if (flags != s->current_irq) {
+ s->current_irq = flags;
+ qemu_set_irq(s->irq, s->current_irq != 0);
+ }
}
static uint64_t pl011_read(void *opaque, hwaddr offset,
--
2.3.0
- [Qemu-devel] [PATCH 0/6] QEMU ARM64 Migration Fixes, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 3/6] hw/char/pl011: don't keep setting the IRQ if nothing changed,
Alex Bennée <=
- [Qemu-devel] [PATCH 2/6] arm_gic_kvm.c: restore config before pending IRQs, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 1/6] target-arm: kvm: save/restore mp state, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 4/6] target-arm/kvm64.c: sync FP register state, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 5/6] target-arm/kvm64: fix save/restore of SPSR regs, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 5/6] target-arm/kvm64: fix save/restore of SPSR registers, Alex Bennée, 2015/02/25
- [Qemu-devel] [PATCH 6/6] target-arm/cpu.h: document why env->spsr exists, Alex Bennée, 2015/02/25