Re: [PATCH] kvmclock: clock should count only if vm is running (v2)
Il 25/06/2013 14:18, Gleb Natapov ha scritto: On Tue, Jun 18, 2013 at 08:38:25PM -0300, Marcelo Tosatti wrote: v2: remove unnecessary runstate_is_running() usage (Paolo) -- kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com Applied, thanks. Cc: qemu-sta...@nongnu.org Gleb, the commit hash is fixed now that you applied the patch---so I cannot just amend it to include the Cc, right? Paolo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] kvmclock: clock should count only if vm is running (v2)
On Mon, Jul 01, 2013 at 01:44:42PM +0200, Paolo Bonzini wrote: Il 25/06/2013 14:18, Gleb Natapov ha scritto: On Tue, Jun 18, 2013 at 08:38:25PM -0300, Marcelo Tosatti wrote: v2: remove unnecessary runstate_is_running() usage (Paolo) -- kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com Applied, thanks. Cc: qemu-sta...@nongnu.org Gleb, the commit hash is fixed now that you applied the patch---so I cannot just amend it to include the Cc, right? Qemu upstream has weird rule that requires patches to be sent on the list with each pull request and this effectively means that it is impossible to do merges which, in turn, means that sometimes rebase is unavoidable. But we try not to do them anyway. -- Gleb. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] kvmclock: clock should count only if vm is running (v2)
On Tue, Jun 18, 2013 at 08:38:25PM -0300, Marcelo Tosatti wrote: v2: remove unnecessary runstate_is_running() usage (Paolo) -- kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com Applied, thanks. diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..98e5ca5 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; -int ret; - -if (s-clock_valid) { -return; -} -ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); -if (ret 0) { -fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); -data.clock = 0; -} -s-clock = data.clock; -/* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ -s-clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; - -data.clock = s-clock; -data.flags = 0; -return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { +struct kvm_clock_data data; + s-clock_valid = false; +data.clock = s-clock; +data.flags = 0; +ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_SET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} + if (!cap_clock_ctrl) { return; } @@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } } +} else { +struct kvm_clock_data data; +int ret; + +if (s-clock_valid) { +return; +} +ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} +s-clock = data.clock; + +/* + * If the VM is stopped, declare the clock state valid to + * avoid re-reading it on next vmsave (which would return + * a different value). Will be reset when the VM is continued. + */ +s-clock_valid = true; } } @@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = { .version_id = 1, .minimum_version_id = 1, .minimum_version_id_old = 1, -.pre_save = kvmclock_pre_save, -.post_load = kvmclock_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), VMSTATE_END_OF_LIST() -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- Gleb. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] kvmclock: clock should count only if vm is running
Hi Marcelo, sorry for the late review. Il 08/06/2013 04:00, Marcelo Tosatti ha scritto: kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Do you have any ideas on how to implement CLOCK_BOOTTIME for kvmclock? I think we need to add more fields for the delta between CLOCK_MONOTONIC and CLOCK_BOOTTIME. Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..7d2d005 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; -int ret; - -if (s-clock_valid) { -return; -} -ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); -if (ret 0) { -fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); -data.clock = 0; -} -s-clock = data.clock; -/* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ -s-clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; - -data.clock = s-clock; -data.flags = 0; -return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { +struct kvm_clock_data data; + Do we need an if (!s-clock_valid) return; here, or an assertion? (Or alternatively, what happens if s-clock_valid == false?) s-clock_valid = false; +data.clock = s-clock; +data.flags = 0; +ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_SET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} + if (!cap_clock_ctrl) { return; } @@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } } +} else { +struct kvm_clock_data data; +int ret; + +if (s-clock_valid) { +return; +} +ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} +s-clock = data.clock; + +/* + * If the VM is stopped, declare the clock state valid to + * avoid re-reading it on next vmsave (which would return + * a different value). Will be reset when the VM is continued. + */ +s-clock_valid = !runstate_is_running(); Here we know that !runstate_is_running() is true (we're in the else branch of if (running)) so it can just be s-clock_valid = true. This matches the false assignment in the other branch. This is just a nit, but it makes the code clearer. Paolo } } @@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = { .version_id = 1, .minimum_version_id = 1, .minimum_version_id_old = 1, -.pre_save = kvmclock_pre_save, -.post_load = kvmclock_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), VMSTATE_END_OF_LIST() -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] kvmclock: clock should count only if vm is running (v2)
v2: remove unnecessary runstate_is_running() usage (Paolo) -- kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..98e5ca5 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; -int ret; - -if (s-clock_valid) { -return; -} -ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); -if (ret 0) { -fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); -data.clock = 0; -} -s-clock = data.clock; -/* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ -s-clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; - -data.clock = s-clock; -data.flags = 0; -return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { +struct kvm_clock_data data; + s-clock_valid = false; +data.clock = s-clock; +data.flags = 0; +ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_SET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} + if (!cap_clock_ctrl) { return; } @@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } } +} else { +struct kvm_clock_data data; +int ret; + +if (s-clock_valid) { +return; +} +ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} +s-clock = data.clock; + +/* + * If the VM is stopped, declare the clock state valid to + * avoid re-reading it on next vmsave (which would return + * a different value). Will be reset when the VM is continued. + */ +s-clock_valid = true; } } @@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = { .version_id = 1, .minimum_version_id = 1, .minimum_version_id_old = 1, -.pre_save = kvmclock_pre_save, -.post_load = kvmclock_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), VMSTATE_END_OF_LIST() -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] kvmclock: clock should count only if vm is running
On Tue, Jun 18, 2013 at 11:02:27AM +0200, Paolo Bonzini wrote: Hi Marcelo, sorry for the late review. Il 08/06/2013 04:00, Marcelo Tosatti ha scritto: kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Do you have any ideas on how to implement CLOCK_BOOTTIME for kvmclock? I think we need to add more fields for the delta between CLOCK_MONOTONIC and CLOCK_BOOTTIME. Unsure. An alternative to new fields is to use MSR_KVM_WALL_CLOCK interface. Looking at two possibilities for catching up with real time on unpause or vmload: 1) Catch up realtime via guest agent. 2) Catch up realtime via kvmclock interface. But it would be good to have proper CLOCK_BOOTTIME behaviour at the same time. Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..7d2d005 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; -int ret; - -if (s-clock_valid) { -return; -} -ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); -if (ret 0) { -fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); -data.clock = 0; -} -s-clock = data.clock; -/* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ -s-clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; - -data.clock = s-clock; -data.flags = 0; -return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { +struct kvm_clock_data data; + Do we need an if (!s-clock_valid) return; here, or an assertion? (Or alternatively, what happens if s-clock_valid == false?) s-clock_valid = true means the clock value at s-clock (saved in QEMU) is valid. At the moment VM begins execution, it becomes invalid (which means synchronizing that value is necessary). For the stopped-running transition, it has no meaning (just as the load functions assume the device state is valid when they are called). That said, i see no reason for additional checks. + */ +s-clock_valid = !runstate_is_running(); Here we know that !runstate_is_running() is true (we're in the else branch of if (running)) so it can just be s-clock_valid = true. This matches the false assignment in the other branch. This is just a nit, but it makes the code clearer. Paolo Sure, resending. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] kvmclock: clock should count only if vm is running
kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti mtosa...@redhat.com diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..7d2d005 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; -int ret; - -if (s-clock_valid) { -return; -} -ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); -if (ret 0) { -fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); -data.clock = 0; -} -s-clock = data.clock; -/* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ -s-clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ -KVMClockState *s = opaque; -struct kvm_clock_data data; - -data.clock = s-clock; -data.flags = 0; -return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { +struct kvm_clock_data data; + s-clock_valid = false; +data.clock = s-clock; +data.flags = 0; +ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_SET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} + if (!cap_clock_ctrl) { return; } @@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } } +} else { +struct kvm_clock_data data; +int ret; + +if (s-clock_valid) { +return; +} +ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, data); +if (ret 0) { +fprintf(stderr, KVM_GET_CLOCK failed: %s\n, strerror(ret)); +abort(); +} +s-clock = data.clock; + +/* + * If the VM is stopped, declare the clock state valid to + * avoid re-reading it on next vmsave (which would return + * a different value). Will be reset when the VM is continued. + */ +s-clock_valid = !runstate_is_running(); } } @@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = { .version_id = 1, .minimum_version_id = 1, .minimum_version_id_old = 1, -.pre_save = kvmclock_pre_save, -.post_load = kvmclock_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), VMSTATE_END_OF_LIST() -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html