Virtual Interrupt Delivery Optimization in ESX4.0


Optimized virtual interrupt delivery in ESX 4.0 improves the performance of some Linux guests. On an I/O completion, previous versions of ESX scheduled the vCPU that originated the I/O request. If this vCPU was found to not be the target vCPU chosen by the guest for further processing the I/O completion interrupt request, the VMM forwarded the I/O completion to the correct target vCPU with an additional inter-processor interrupt. ESX 4.0 avoids the need for these additional interrupts by predicting which vCPU is the target of a particular IRQ and delivering the I/O completion to it instead of to the originating vCPU. This reduces the CPU overhead substantially.

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About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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