similar to: [PATCH 7/9] Fix nohz compile.patch

VMI timer code. It works by taking over the local APIC clock when APIC is configured, which requires a couple hooks into the APIC code. The backend timer code could be commonized into the timer infrastructure, but there are some pieces missing (stolen time, in particular), and the exact semantics of when to do accounting for NO_IDLE need to be shared between different hypervisors as well. So

VMI timer code. It works by taking over the local APIC clock when APIC is configured, which requires a couple hooks into the APIC code. The backend timer code could be commonized into the timer infrastructure, but there are some pieces missing (stolen time, in particular), and the exact semantics of when to do accounting for NO_IDLE need to be shared between different hypervisors as well. So

VMI timer code. It works by taking over the local APIC clock when APIC is configured, which requires a couple hooks into the APIC code. The backend timer code could be commonized into the timer infrastructure, but there are some pieces missing (stolen time, in particular), and the exact semantics of when to do accounting for NO_IDLE need to be shared between different hypervisors as well. So

VMI timer code. It works by taking over the local APIC clock when APIC is configured, which requires a couple hooks into the APIC code. The backend timer code could be commonized into the timer infrastructure, but there are some pieces missing (stolen time, in particular), and the exact semantics of when to do accounting for NO_IDLE need to be shared between different hypervisors as well. So

Convert VMI timer to use clock events, making it properly able to use the NO_HZ infrastructure. On UP systems, with no local APIC, we just continue to route these events through the PIT. On systems with a local APIC, or SMP, we provide a single source interrupt chip which creates the local timer IRQ. It actually gets delivered by the APIC hardware, but we don't want to use the same local

Convert VMI timer to use clock events, making it properly able to use the NO_HZ infrastructure. On UP systems, with no local APIC, we just continue to route these events through the PIT. On systems with a local APIC, or SMP, we provide a single source interrupt chip which creates the local timer IRQ. It actually gets delivered by the APIC hardware, but we don't want to use the same local

In a virtualized environment, virtual machines will time share the system with each other and with other processes running on the host system. Therefore, a VM's virtual CPUs (VCPUs) will be executing on the host's physical CPUs (pcpus) for only some portion of time. The VMI exposes a paravirtual view of time to the guest operating systems so that they may operate more effectively in a

In a virtualized environment, virtual machines will time share the system with each other and with other processes running on the host system. Therefore, a VM's virtual CPUs (VCPUs) will be executing on the host's physical CPUs (pcpus) for only some portion of time. The VMI exposes a paravirtual view of time to the guest operating systems so that they may operate more effectively in a

Critical bugfixes for the VMI-Timer code. 1) Do not setup a one shot alarm if we are keeping the periodic alarm armed. Additionally, since the periodic alarm can be run at a lower rate than HZ, let's fixup the guard to the no-idle-hz mode appropriately. This fixes the bug where the no-idle-hz mode might have a higher interrupt rate than the non-idle case. 2) The interrupt handler can no

Critical bugfixes for the VMI-Timer code. 1) Do not setup a one shot alarm if we are keeping the periodic alarm armed. Additionally, since the periodic alarm can be run at a lower rate than HZ, let's fixup the guard to the no-idle-hz mode appropriately. This fixes the bug where the no-idle-hz mode might have a higher interrupt rate than the non-idle case. 2) The interrupt handler can no

In order to share the common code in tsc.c which does CPU Khz calibration, we need to make an accurate value of CPU speed available to the tsc.c code. This value loses a lot of precision in a VM because of the timing differences with real hardware, but we need it to be as precise as possible so the guest can make accurate time calculations with the cycle counters. Signed-off-by: Zachary Amsden

In order to share the common code in tsc.c which does CPU Khz calibration, we need to make an accurate value of CPU speed available to the tsc.c code. This value loses a lot of precision in a VM because of the timing differences with real hardware, but we need it to be as precise as possible so the guest can make accurate time calculations with the cycle counters. Signed-off-by: Zachary Amsden

The custom_sched_clock hook is broken. The result from sched_clock needs to be in nanoseconds, not in CPU cycles. The TSC is insufficient for this purpose, because TSC is poorly defined in a virtual environment, and mostly represents real world time instead of scheduled process time (which can be interrupted without notice when a virtual machine is descheduled). To make the scheduler

The custom_sched_clock hook is broken. The result from sched_clock needs to be in nanoseconds, not in CPU cycles. The TSC is insufficient for this purpose, because TSC is poorly defined in a virtual environment, and mostly represents real world time instead of scheduled process time (which can be interrupted without notice when a virtual machine is descheduled). To make the scheduler

A NO_IDLE_HZ implementation is provided for i386 VMI builds. When a VCPU enters its idle loop, it disables its periodic alarm and sets up a one shot alarm for the next time event. That way, it does not become ready to run just to service the periodic alarm interrupt. Instead, it can remain halted until there is some real work pending for it. This allows the hypervisor to use the physical

A NO_IDLE_HZ implementation is provided for i386 VMI builds. When a VCPU enters its idle loop, it disables its periodic alarm and sets up a one shot alarm for the next time event. That way, it does not become ready to run just to service the periodic alarm interrupt. Instead, it can remain halted until there is some real work pending for it. This allows the hypervisor to use the physical

The xen_play_dead is an undead function. When the vCPU is told to offline it ends up calling xen_play_dead wherin it calls the VCPUOP_down hypercall which offlines the vCPU. However, when the vCPU is onlined back, it resumes execution right after VCPUOP_down hypercall. That was OK (albeit the API for play_dead assumes that the CPU stays dead and never returns) but with commit 4b0c0f294 (tick:

At http://namei.org/misc/lguest/patches/time/v02/ Current status: - Resync to recent upstream lguest patch queue - Rudimentary clock event device is working, but with a significant performance hit - Old TSC code included, still needs to be modified to handle freq change Next: - Check for pending interrupts after they're enabled again per suggestion from Rusty. -- James Morris

At http://namei.org/misc/lguest/patches/time/v02/ Current status: - Resync to recent upstream lguest patch queue - Rudimentary clock event device is working, but with a significant performance hit - Old TSC code included, still needs to be modified to handle freq change Next: - Check for pending interrupts after they're enabled again per suggestion from Rusty. -- James Morris

Hi Andi, This is a set of updates for the firstfloor patch queue. Quick rundown: revert-mm-x86_64-mm-account-for-module-percpu-space-separately-from-kernel-percpu.patch separate-module-percpu-space.patch Update the module percpu accounting patch fix-ff-allow-percpu-variables-to-be-page-aligned.patch Make sure the percpu memory allocation is page-aligned