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Ship it!


Ship It!

- Ali Saidi


On June 3, 2013, 3:40 a.m., Andreas Sandberg wrote:
> 
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> http://reviews.gem5.org/r/1887/
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> (Updated June 3, 2013, 3:40 a.m.)
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> 
> Review request for Default.
> 
> 
> Description
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> 
> Changeset 9738:160272d942df
> ---------------------------
> kvm: Don't handle IO and execute in the same tick
> 
> We currently execute instructions in the guest and then handle any IO
> request right after we break out of the virtualized environment. This
> has the effect of executing IO requests in the exact same tick as the
> first instruction in the sequence that was just run. There seem to be
> cases where this simplification upsets some timing-sensitive devices.
> 
> This changeset splits execute and IO (and other services) across
> multiple ticks. This is implemented by adding a separate
> RunningService state to the CPU state machine. When a VM requires
> service, it enters into this state and pending IO is then serviced in
> the future instead of immediately. The delay between getting the
> request and servicing it depends on the number of cycles executed in
> the guest, which allows other components to catch up with the CPU.
> 
> 
> Diffs
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> 
>   src/cpu/kvm/arm_cpu.hh 16f9d1fd37da 
>   src/cpu/kvm/arm_cpu.cc 16f9d1fd37da 
>   src/cpu/kvm/base.hh 16f9d1fd37da 
>   src/cpu/kvm/base.cc 16f9d1fd37da 
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> Diff: http://reviews.gem5.org/r/1887/diff/
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> 
> Testing
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> 
> 
> Thanks,
> 
> Andreas Sandberg
> 
>

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