Re: [PATCH 0/2] Batch writes to MMIO

[Anthony Liguori <anthony@codemonkey.ws>]

Avi Kivity wrote:
> Laurent Vivier wrote:
>   
> That's the lovely animation. You can time XP startup, or look at system 
> time in 'top' once it stabilizes.  Also compare total host_state_reloads 
> to boot in kvm_stat (each costs 5 usec, after discount).
>   

Win2k's boot up animation (the moving bar) is done in VGA planar mode.  
You should be able to time the difference in startup.

>>  and by group of 10 with XP
>> when we move a window.
>>   
>>     
>
> That's probably programming the cirrus blitter, also a candidate for 
> batching, but probably not measurable.  Maybe one of those Windows 
> graphics benchmarks which draw tons of rectangles very fast and cause 
> epilepsy seizures.
>
> I guess most interesting is e1000, if we need to do more than one mmio 
> to start transmitting.
>   

The ne2k is pretty mmio heavy.  You should be able to observe a boost 
with something like iperf (guest=>host) I would think if this is a real 
savings.

Regards,

Anthony Liguori



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