Re: [BUG] Paravirtual time accounting / IRQ time accounting

From: Rik van Riel
Date: Sat Mar 22 2014 - 10:57:50 EST


On 03/22/2014 03:15 AM, lwcheng@xxxxxxxxx wrote:

> I observe that sometimes irq_time only includes "part" of steal_time.
>
> Like you said, irq_time is in dozens-of-microseconds. In VMs, as all
> devices seen are virtual ones, irq_time seems to be not as desired
> as it is in physical hosts.
>
> A quick (but not radical) solution may be:
> disable CONFIG_IRQ_TIME_ACCOUNTING if CONFIG_PARAVIRT is selected.
> Just adopt tick-based accounting: CONFIG_TICK_CPU_ACCOUNTING
>
> I am thinking what irq_time really *means* in VMs.

That is not really an option for Linux distributions, which tend
to run the same kernel image on the host and in the guest...

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