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gmknt
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Contributor

ESXI 5.5: performance difference upon guest-reboot (win7 guest, VMDirectPath I/O pass-through)

To evaluate performance and compare a system natively vs virtualized+passthrough (and to some other solutions), I ran a couple of benchmarks on each.

For some reason, my windows 7 guest os seems to operate in two different performance modes. In "mode 1", furmark (a benchmark to test gpu, with 1080p preset) will result in about 3070 points/51fps, "mode 2" results in 2680 points/44fps (also 1080p preset). As long as the vm is up, results will always be close to the ones mentioned (+/- few points). The only thing I do to "switch" those "modes" is to reboot the vm, and I will never know in which mode I am in until I run a benchmark and check the result.

Furmark here is just an example, the behavior/difference exists in other benchmarks/settings too.

Host machine:

ESXi 5.5.0 update 2

Intel i7 4790k

ASRock Z97 Pro 4

AMD R9 280

Guest:

Win7 Pro with recent updates and drivers, AMD R9 280 graphics card is being passed through.

For anyone interested, furmark on native windows 7 will also be around 3070 points.

I am not an expert in anything VMWare and am looking forward to anyones input to shed light on the situation here.

So.. what do you think is going on?

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