Re: [Xen-devel] [PATCH] remove blocked time accounting from xen "clockchip"

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.01.12 at 20:42, Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> wrote:
> I finally got some time to look at them and I think they are these ones:
> 
> git log --oneline 
> e03b644fe68b1c6401465b02724d261538dba10f..3c404b578fab699c4708279938078d9404b
> 255a4 
> 3c404b5 KVM guest: Add a pv_ops stub for steal time
> c9aaa89 KVM: Steal time implementation
> 9ddabbe KVM: KVM Steal time guest/host interface
> 4b6b35f KVM: Add constant to represent KVM MSRs enabled bit in guest/host 
> interface
> 
> What is interesting is that they end up inserting a bunch of:
> 
>  
> +       if (steal_account_process_tick())
> +               return;
> +
> 
> in irqtime_account_process_tick and in account_process_tick.

And this (particularly the "return" part of it) is what I have a hard
time to understand: How can it be correct to not do any of the
other accounting? After all, the function calls only
account_steal_time(), but its certainly going to be common that
part of the time was stolen, and part was spent executing.

Further, it's being called only from the process tick accounting
functions, but clearly part of idle or interrupt time can also be
stolen.

Jan


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