Linux 6.2 Aims To Ship Updated Zstd Implementation

While various Linux kernel components are increasingly making use of the Zstandard compression algorithm, the Zstd code in the kernel has tended to trail behind upstream. Fortunately, a push is underway to get Zstd 1.5.2 in the Linux 6.2 kernel cycle that kicks off at year's end.

The last time the Zstd code within the kernel was updated was a year ago with Linux 5.16 when taking it to Zstd 1.4.10. At that point the Linux kernel Zstd implementation prior to that was four years out of date. But the hope now is that with Linux 6.2 the kernel code can be brought up to the Zstd 1.5.2 state so that it's finally at close parity to upstream.

Nick Terrell of Facebook/Meta sent out the set of patches last night for updating the Linux kernel's Zstandard implementation against Zstd 1.5.2. Terrell noted in that patch series:

The latest upstream release is v1.5.2, and I am targeting this patch for the v6.2 kernel. We will be working on a new upstream release later this year. If it is ready by the team the v6.2 merge window rolls around, I will add another update patch to this series.

I will be merging this into my `zstd-next` branch which gets pulled into `linux-next` for testing.

Let's hope this does indeed happen for Linux 6.2 to finally move the code past the Zstd 1.4.x state.

Zstandard

In the patch updating to the v1.5.2 state, when looking at the updated Zstd with Btrfs transparent file-system compression performance the decompression speed was "a small win across the board" and at lower compression levels the compression speed and compression ratio were both better than the prior kernel code.