Messages in this thread | | | Date | Mon, 12 Dec 2011 20:21:46 +0200 | From | Avi Kivity <> | Subject | Re: [patch 0/3] kvm tool: Serial emulation overhaul |
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On 12/12/2011 01:02 PM, Alan Cox wrote: > > > You can emulate a chip with a 64byte or so FIFO. You can do I/O cycle > > > prediction in the kernel part and you can use the empty bit as a clue > > > (which is what most serial<->ethernet widgetry does). > > > > The performance problems here aren't the same performance problems you > > have on real hardware. The problem here is that it costs 40k cycles for > > the guest to access the emulated chip. > > How much of that 40K cycles is bouncing back and forth into emulation > layers and how much of it is the kernel trap ? >
30K of those cycles are only in Sasha's mind, the real figure is 10K (and likely lower with newer hardware).
-- error compiling committee.c: too many arguments to function
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