4 ms·
Who actually runs Centos 7 ( Kernel 3.10 ) for benchmarks in 2021? Run something recent like Ubuntu 20 + KVM, you will see big difference. I don't beleive moder
by Thaxll 5y ago
Who actually runs Centos 7 ( Kernel 3.10 ) for benchmarks in 2021? Run something recent like Ubuntu 20 + KVM, you will see big difference. I don't beleive modern virtualization has ~20% overhead ( it should be less than 5% ).
- marginalia_nu 5y agoCan you find sources for those "less than 5%"-numbers form people who aren't selling kubernetes or cloud-related services? It's generally pretty easy to construct benchmarks that make look favorable. It's why there's constantly blog posts to the effect of "$INTERPRETED_HIGH_LEVEL_LANGUAGE is faster than C++".
- grepfru_it 5y agoI mean one could say kubernetes has virtualized components, and requires VT-d extensions to operate at an accelerated speed, but I don't think containers are truly virtualized. So you can probably get away with a less than 5% benchmark if the stars aligned. With a hypervisor you're looking at 10-15% overhead, typically. maybe getting down to 7-12% using tricks (paravirtualization, pci-passthrough etc). In my environment i am around 12% OH on a good day
- merb 5y agoi've seen way les than 10% overhead on modern hardware with sr-iov compat devices. it really depends on your network card/raid controller. some servers (and some cpus) are just not optimal for running virtualized stuff.
- grepfru_it 5y ago*using tricks :)
- w7 5y agoIndeed, standard container runtimes neither require VT-x (virtualization instructions) or VT-d (IOMMU for PCIe devices). They're "just" process isolation (cgroups), network stack isolation (netns), and filesystem isolation (overlayfs). Workloads on Kubernetes are not using virtual hardware unless you choose a managed provider or container runtime that states they are.
- jiggawatts 5y agoIn my experience 20% is about right for the minimum overhead for general workloads. 5% is achievable only for pure user-mode CPU loads with minimal I/O.
- xxpor 5y agoYou can get much lower with modern SR-IOV devices.
- Thaxll 5y agohttps://www.brendangregg.com/blog/2017-11-29/aws-ec2-virtualization-2017.html https://www.brendangregg.com/blog/2017-11-29/aws-ec2-virtual... Virtualized in Hardware: Hardware support for virtualization, and near bare-metal speeds. I'd expect between 0.1% and 1.5% overhead.
- tln 5y agoYeah, that is weird. CentOS 7 is from 2009. CentOS 8 is from 2015 Neither supports io_uring (although I don't think nginx does either)