While we have conducted studies related to the Linux kernel performance in the past such as benchmarking up to twelve kernel releases, going out the door this morning are the results from the largest-ever Linux kernel comparison conducted at Phoronix, and very likely the largest ever of its kind regardless of source. Every major Linux kernel release from Linux 2.6.12, which was released in mid-2005, up through the latest Linux 2.6.37 development code was tested. This represents the past five years of the Linux kernel and shows how the performance has evolved over the past 25 stable kernel releases and the most recent 2.6.37 development kernel.
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When this testing began last week, it really was unknown what to expect since we have never carried out a Linux kernel performance comparison to this scale before nor have we ever seen such a report. Some users and developers that we talked to beforehand bet the performance of Linux kernel would drop over the past five years as the Linux kernel gets increasingly large and more cruft is added, but in most areas, this is actually not the case. However, at the same time, in few areas did the Linux kernel performance actually increase over the 26 versions of the Linux 2.6 kernel that were benchmarked.
As the Linux kernel aged, the performance improved in some areas like with John The Ripper, Himeno, code compilation performance, PostMark, FS-Mark, and the Threaded I/O Tester. At least this was the case with the x86_64 Linux kernel when a KVM-virtualized copy of Fedora. Where the Linux kernel is left being slower at this point is with GnuPG, Loopback TCP Network Performance, IOzone, and in other areas on a more miniscule scale. For many of the application benchmarks the Linux kernel advancements caused little performance change, at least for a multi-core x86_64 system running in a virtual machine.
Very cool that they did this and there were definitely some surprises. Along those lines, if anyone is interested in performance testing, definitely check out the Phoronix Testing Suite!
