Re: [PATCH v3 1/3] Introduce a workqueue to deliver PIT timer interrupts.

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

On 2010-06-16 23:11, Chris Lalancette wrote:
> We really want to "kvm_set_irq" during the hrtimer callback,
> but that is risky because that is during interrupt context.
> Instead, offload the work to a workqueue, which is a bit safer
> and should provide most of the same functionality.

Unfortunately, workqueues do not have fixed kthread associations (and
"kvm-pit-wq" would be too unspecific when running multiple VMs). So I
just realized that this subtly breaks the ability to run KVM guests with
RT priority (boot managers with timeouts hang as the workqueue starves).

Before throwing some kthread_worker at this, could someone help me
recalling what was "risky" here? That the PIT IRQ may have to be
broadcast to a large number of VCPUs? I would offer to include this
information in my changelog. ;)

Thanks,
Jan

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Corporate Competence Center Embedded Linux
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