RE: [Xen-devel] [RFC] Scheduler work, part 1: High-level goals and interface.

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Ian Pratt [mailto:Ian.Pratt@xxxxxxxxxxxxx] 
>Sent: 2009年4月12日 1:12
>> >Possibly having two modes of operation would be good thing:
>> >
>> > 1. explicitly present HT to guests and gang schedule threads
>> >
>> > 2. normal free-for-all with HT aware accounting.
>> >
>> >Of course, #1 isn't optimal if guests may migrate between HT
>> >and non-HT systems.
>> 
>> what do you mean by 'free-for-all'?
>
>Same as today, i.e. we don't gang schedule and all threads are 
>available for running VCPUs. 
>
>I think it's reasonable to have two different modes of 
>operation. For some CPU-intensive server virtualization-type 
>workloads the admin basically wants to partition the machine. 
>In this situation it's reasonable to expose the physical 
>topology to guests (not just hyperthreads, but potentially 
>cores/sockets/nodes and all the gory SLIT/SRAT tables stuff too). 
>
>For more general virtualization workloads where the total 
>number of VCPUs is rather greater than the number of physical 
>CPUs then the current behaviour is preferable. HT aware 
>accounting will mean that VCPUs that run concurrently on the 
>same core will be charged less than the full period they are 
>scheduled for.
>

Agree.

Thanks
Kevin

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