Bcachefs may be the newest, shiniest Linux filesystem that offers a number of advanced features, but performance doesn’t yet appear to be one of them.

Bcachefs is a copy-on-write (COW) filesystem, similar to the older, more mature Btrfs. Bcachefs is designed to offer many of the same features as Btrfs without the drawbacks. Unfortunately, it has had a rocky road to inclusion in the Linux kernel, with developer Kent Overstreet often clashing with Linux creator Linus Toralds, even earning a temporary ban from contributing to the kernel.

Given that it is now considered “soft-frozen” and will soon lose the “experimental” flag, Phoronix decided to do benchmarks comparing Bcachefs with other Linux filesystems. In the tests, XFS came out on top, followed by F2FS in second place, EXT4 and Btrfs tied for third, and Bcachefs coming in a distant last.

As Phoronix points out, however, raw performance isn’t the only factor to consider.

When taking the geometric mean of all the file-systems tested, XFS was by far the fastest with this testing on Linux 6.15 and using a Crucial T705 NVMe PCIe 5.0 SSD. With each file-system at its defaults, XFS was 20% faster than F2FS as the next fastest file-system. EXT4 and Btrfs meanwhile were tied for third. Bcachefs out-of-the-box on this PCIe 5 SSD was in a distant last place on Linux 6.15 Git.

Of course, there are more factors to consider when choosing a Linux file-system besides just the raw performance… Features and data integrity/safety and overall file-system maturity being among the other key areas. Some of the non-default file-system mount options can also greatly influence the file-system for better or worse depending upon your workloads and tailored setup. In any event for those wondering roughly how these mainline Linux file-systems are performing, now you have a fresh perspective from Linux 6.15 that will be out as stable later this month.

Bcachefs shows a lot of promise, offering many of the benefits of Btrfs while trying to address its weaknesses. Nonetheless, the filesystem still has a ways to go before it can effectively compete with some of its more established rivals.