Is The Linux Kernel Scheduler Worse Than People Realize?
There is this paper entitled The Linux Scheduler: a Decade of Wasted Cores that covers the research done on the Linux kernel's scheduler to indicate it's suboptimal.
Going along with that paper are these PDF slides further talking about how the Linux scheduler is doing a bad job and often overloading some CPU cores while leaving other CPU cores idle.
The researchers were able to fix some of the scheduler bugs where there was a 23% performance improvement on a popular database with TPC or a shocking 137x performance improvement on HPC workloads. However, not at all of the scheduler issues can be easily addressed with simple patches but would require a more thorough redesign.
The researchers concluded, "more research must be directed towards implementing an efficient and reliable scheduler for multicore architectures!"