Re: [Xen-devel] Xen spinlock questions

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Keir Fraser wrote:
> On 15/8/08 13:15, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
>   
>> I can't really explain the results of testing with this version of the patch:
>> While the number of false wakeups got further reduced by somewhat
>> less than 20%, both time spent in the kernel and total execution time
>> went up (8% and 4% respectively) compared to my original (and from
>> all I can tell worse) version of the patch. Nothing else changed as far as
>> I'm aware.
>>     
>
> That is certainly odd. Presumably consistent across a few runs? I can't
> imagine where extra time would be being spent though...
>   

2 locked instructions in vcpu_unblock() when using polling?  Doesn't
seem like 8%-worth of time though.

    J

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