From: Jan Kiszka <jan.kiszka@siemens.com> To: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com> Cc: kvm <kvm@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>, Michael Tokarev <mjt@tls.msk.ru>, qemu-devel <qemu-devel@nongnu.org>, qemu-stable <qemu-stable@nongnu.org>, Gerd Hoffmann <kraxel@redhat.com> Subject: [PATCH uq/master 1/2] kvm: i8254: Cache kernel clock offset in KVMPITState Date: Tue, 14 Aug 2012 10:24:03 +0200 [thread overview] Message-ID: <502A0B23.2080701@siemens.com> (raw) To prepare the final fix for clock calibration issues with the in-kernel PIT, we want to cache the offset between vmclock and the clock used by the in-kernel PIT. So far, we only need to update it when the VM state changes between running and stopped because we only read the in-kernel PIT state while the VM is running. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- hw/kvm/i8254.c | 38 ++++++++++++++++++++++++-------------- 1 files changed, 24 insertions(+), 14 deletions(-) diff --git a/hw/kvm/i8254.c b/hw/kvm/i8254.c index c5d3711..c235d80 100644 --- a/hw/kvm/i8254.c +++ b/hw/kvm/i8254.c @@ -35,7 +35,8 @@ typedef struct KVMPITState { PITCommonState pit; LostTickPolicy lost_tick_policy; - bool state_valid; + bool vm_stopped; + int64_t kernel_clock_offset; } KVMPITState; static int64_t abs64(int64_t v) @@ -43,19 +44,11 @@ static int64_t abs64(int64_t v) return v < 0 ? -v : v; } -static void kvm_pit_get(PITCommonState *pit) +static void kvm_pit_update_clock_offset(KVMPITState *s) { - KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit); - struct kvm_pit_state2 kpit; - struct kvm_pit_channel_state *kchan; - struct PITChannelState *sc; int64_t offset, clock_offset; struct timespec ts; - int i, ret; - - if (s->state_valid) { - return; - } + int i; /* * Measure the delta between CLOCK_MONOTONIC, the base used for @@ -72,6 +65,21 @@ static void kvm_pit_get(PITCommonState *pit) clock_offset = offset; } } + s->kernel_clock_offset = clock_offset; +} + +static void kvm_pit_get(PITCommonState *pit) +{ + KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit); + struct kvm_pit_state2 kpit; + struct kvm_pit_channel_state *kchan; + struct PITChannelState *sc; + int i, ret; + + /* No need to re-read the state if VM is stopped. */ + if (s->vm_stopped) { + return; + } if (kvm_has_pit_state2()) { ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit); @@ -106,7 +114,7 @@ static void kvm_pit_get(PITCommonState *pit) sc->mode = kchan->mode; sc->bcd = kchan->bcd; sc->gate = kchan->gate; - sc->count_load_time = kchan->count_load_time + clock_offset; + sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset; } sc = &pit->channels[0]; @@ -211,10 +219,12 @@ static void kvm_pit_vm_state_change(void *opaque, int running, KVMPITState *s = opaque; if (running) { - s->state_valid = false; + kvm_pit_update_clock_offset(s); + s->vm_stopped = false; } else { + kvm_pit_update_clock_offset(s); kvm_pit_get(&s->pit); - s->state_valid = true; + s->vm_stopped = true; } } -- 1.7.3.4
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kiszka <jan.kiszka@siemens.com> To: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com> Cc: kvm <kvm@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>, Michael Tokarev <mjt@tls.msk.ru>, qemu-devel <qemu-devel@nongnu.org>, qemu-stable <qemu-stable@nongnu.org>, Gerd Hoffmann <kraxel@redhat.com> Subject: [Qemu-devel] [PATCH uq/master 1/2] kvm: i8254: Cache kernel clock offset in KVMPITState Date: Tue, 14 Aug 2012 10:24:03 +0200 [thread overview] Message-ID: <502A0B23.2080701@siemens.com> (raw) To prepare the final fix for clock calibration issues with the in-kernel PIT, we want to cache the offset between vmclock and the clock used by the in-kernel PIT. So far, we only need to update it when the VM state changes between running and stopped because we only read the in-kernel PIT state while the VM is running. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- hw/kvm/i8254.c | 38 ++++++++++++++++++++++++-------------- 1 files changed, 24 insertions(+), 14 deletions(-) diff --git a/hw/kvm/i8254.c b/hw/kvm/i8254.c index c5d3711..c235d80 100644 --- a/hw/kvm/i8254.c +++ b/hw/kvm/i8254.c @@ -35,7 +35,8 @@ typedef struct KVMPITState { PITCommonState pit; LostTickPolicy lost_tick_policy; - bool state_valid; + bool vm_stopped; + int64_t kernel_clock_offset; } KVMPITState; static int64_t abs64(int64_t v) @@ -43,19 +44,11 @@ static int64_t abs64(int64_t v) return v < 0 ? -v : v; } -static void kvm_pit_get(PITCommonState *pit) +static void kvm_pit_update_clock_offset(KVMPITState *s) { - KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit); - struct kvm_pit_state2 kpit; - struct kvm_pit_channel_state *kchan; - struct PITChannelState *sc; int64_t offset, clock_offset; struct timespec ts; - int i, ret; - - if (s->state_valid) { - return; - } + int i; /* * Measure the delta between CLOCK_MONOTONIC, the base used for @@ -72,6 +65,21 @@ static void kvm_pit_get(PITCommonState *pit) clock_offset = offset; } } + s->kernel_clock_offset = clock_offset; +} + +static void kvm_pit_get(PITCommonState *pit) +{ + KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit); + struct kvm_pit_state2 kpit; + struct kvm_pit_channel_state *kchan; + struct PITChannelState *sc; + int i, ret; + + /* No need to re-read the state if VM is stopped. */ + if (s->vm_stopped) { + return; + } if (kvm_has_pit_state2()) { ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit); @@ -106,7 +114,7 @@ static void kvm_pit_get(PITCommonState *pit) sc->mode = kchan->mode; sc->bcd = kchan->bcd; sc->gate = kchan->gate; - sc->count_load_time = kchan->count_load_time + clock_offset; + sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset; } sc = &pit->channels[0]; @@ -211,10 +219,12 @@ static void kvm_pit_vm_state_change(void *opaque, int running, KVMPITState *s = opaque; if (running) { - s->state_valid = false; + kvm_pit_update_clock_offset(s); + s->vm_stopped = false; } else { + kvm_pit_update_clock_offset(s); kvm_pit_get(&s->pit); - s->state_valid = true; + s->vm_stopped = true; } } -- 1.7.3.4
next reply other threads:[~2012-08-14 8:24 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-08-14 8:24 Jan Kiszka [this message] 2012-08-14 8:24 ` [Qemu-devel] [PATCH uq/master 1/2] kvm: i8254: Cache kernel clock offset in KVMPITState Jan Kiszka 2012-08-14 8:24 ` [PATCH uq/master 2/2] kvm: i8254: Finish time conversion fix Jan Kiszka 2012-08-14 8:24 ` [Qemu-devel] " Jan Kiszka 2012-08-14 19:00 ` [PATCH uq/master 1/2] kvm: i8254: Cache kernel clock offset in KVMPITState Marcelo Tosatti 2012-08-14 19:00 ` [Qemu-devel] " Marcelo Tosatti
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