Over the weekend, Linus Torvalds released the next Linux kernel: Linux 5.9. Torvalds said, “OK, so I’ll be honest — I had hoped for quite a bit fewer changes this last week, but at the same time there doesn’t really seem to be anything particularly scary in here.”
So, if you’re feeling brave, and you know how to compile your own Linux kernel, you can download all 115.5 MBs of the compressed Linux kernel 5.9 archive from kernel.org. Most of you, though, can afford to wait for it to appear in Linux distributions. That means, if you use a mainstream Linux distribution such as Fedora or Ubuntu, you can expect to run in their first 2021 releases.
You don’t have to be in a rush. The biggest change, support for the FSGSBASE instruction in Intel Ivy Bridge and later and AMD processors, will improve performance. But it only shows up if you’re really pushing your RAM with many different loads. If you beat up your Linux server a lot, you’ll see the change. I doubt a desktop user will spot it.
There is one noteworthy exception. If you’re a Graphene user, it makes it easier and safer to use Intel’s Software Guard Extensions (SGX) and, in particular, to use the heretofore unsupported FSGSBASE instructions. In the past, Graphene users, whether they knew it or not, were using an insecure kludge to make the program work. This isn’t what you want in a “security” program.
As with other programs, start using SGX and FSGSBASE. However, this change will make much more of a difference to all users. In the meantime, more users will see better memory management on their machines. This comes from a trio of changes. In particular, I expect users running containers on their servers or cloud instances will get a lot more bang for their memory buck.
Linux’s file systems have also got a new coat of polish. This includes the most popular systems including Btrfs, ext4, F2FS, and XFS.
The most important change in storage will probably be the improved support for NVM Express NVMe 2.0. This is used for solid-state devices (SSD) and memory/storage crossovers such as flash-based storage technologies and NAND and Intel’s Optane. While people running desktops will see something of a speed boost, it’s sysadmins running servers and cloud who will see the most improvement.
The same high-end computer folks will be happy to see an improved Linux task scheduler that supports a deadline scheduling class. Until this release, the scheduler couldn’t deal well with computers, which had multiple CPUs with different performance levels. Now, the scheduler can be made aware of each processor’s speed and make appropriate deadline scheduling decisions.
Put it all together, and you have not a great Linux kernel release, but a good one, which will give particular users a much-appreciated speed boost.