On 05/31/2017 11:56 AM, Maurício Almeida wrote: > The Traffic of Virtio was 956 MB/s while e1000 Emulated Driver was 192 > MB/s, both using Packet size of 1518 Bytes. The quick answer - yes, that's the expected results, because paravirt is SOOO much more direct than fully-emulated. Everything done in the e1000 driver has to emulate what hardware would do, which tends to be a LOT of register reads and writes to device memory, which in turn implies a LOT of VMEXITs with corresponding overhead as you are paging between the guest and host to handle the full sequence. Meanwhile, the virtio driver was designed from the ground up to be as efficient as possible, by intentionally arranging memory layout and handshake protocols so that there are as few memory-mapped register writes, and therefore as few VMEXITs, as possible, for better speed and multithreading. > > Why when it used e1000 Emulated Driver the traffic was to low and use only > one Cpu all the time? For any modern OS, the e1000 driver should only be used as a crutch to get the system up and running until you can install and switch over to the virtio drivers (we have it because it is a driver that is most likely already installed on a guest OS out-of-the-box, while the virtio driver might be an extra download or install after the initial guest install has completed). So optimizing the e1000 driver to run on multiple vcpus is not our priority; rather, you should be optimizing your guest provisioning setup to get switched over to the virtio drivers as soon as possible. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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