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Re: [RFC PATCH v1 1/6] sched: track time spent in IRQ handler
- To: "jgross@xxxxxxxx" <jgross@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Date: Fri, 12 Jun 2020 11:26:56 +0000
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- Delivery-date: Fri, 12 Jun 2020 11:27:12 +0000
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- Thread-topic: [RFC PATCH v1 1/6] sched: track time spent in IRQ handler
Hi Jurgen,
thanks for the review
On Fri, 2020-06-12 at 06:36 +0200, Jürgen Groß wrote:
> On 12.06.20 02:22, Volodymyr Babchuk wrote:
[...]
> > +void vcpu_end_irq_handler(void)
> > +{
> > + int delta;
> > +
> > + if (is_idle_vcpu(current))
> > + return;
> > +
> > + ASSERT(current->irq_nesting);
> > +
> > + if ( --current->irq_nesting )
> > + return;
> > +
> > + /* We assume that irq handling time will not overflow int */
>
> This assumption might not hold for long running VMs.
Basically, this value holds time span between calls to schedule(). This
variable gets zeroed out every time scheduler requests for time
adjustment value. So, it should not depend on total VM run time.
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