Linux 4.0 To Linux 4.15 Kernel Benchmarks

[cj.wijtmans]

Yes, just continuing the trend:
https://en.wikipedia.org/wiki/Critic...el_performance
"Citing an internal Intel study that tracked Linux kernel releases, Bottomley said Linux performance had dropped about two per centage points at every release, for a cumulative drop of about 12 per cent over the last ten releases. "Is this a problem?" he asked Linus Torvalds.
-We're getting bloated and huge. Yes, it's a problem"

Looks like i will be using BSD soon if this does not change. Perhaps Linux should start experimenting with having an internal microkernel. I have personally abandoned the linux desktop already because of its messy ecosystem.

[rick-pri]

This is a pretty tame set of scenarios which were tested here.

If you really want to make Intel look bad in terms of benchmarks with a real world horror show (which I experienced on AWS), you go with an Ivy Bridge, or earlier, processor (c3 instances), with a machine which is a hypervisor, you then run a VM with PostgreSQL (an early 9.x version) with a load on the network (15Mb/s should do it over about 30 connections which are constantly cycling) and not enough memory to fit everything into RAM so that the disk gets accessed frequently, and then generate some kernel calls on the other VMs.

You'll see about a 50% reduction in performance and see that latency comes into play so that everything starts to grind to a halt as the TLB is being flushed near constantly.

The decline in the Apache and NGINX benchmark scores is remarkable. What's the story there?

Certain network/disk IO ops require a TLB flush and webservers do a bunch of that serving incoming connections. I remember seeing a whole list of what causes switching to the kernel (which causes a TLB flush and additional latency) somewhere and network and disk IO operations were in there.