Bluefin stutters on slow SDDs - BTRFS likely culprit

[Mestar71]

Dear fellow palaeontologists,
first of all I would like to thank all the developers for the great flock of dinosaur-related distros.

My experiences with bazzite and bluefin have so far been great,
but I still have one thing to note - XFS-based LTS version seems substantially more responsive than the BTRFS-based on the systems with slower SSDs (dram-less, low capacity) and HDDs that I used to evaluate the distros.

On BTRFS-based versions, I noticed frequent stutterings and GUI freezes (though only on slower SSDs).
No intervention in mount options nor changing the disk scheduler would help. The only thing that made it satisfactory was the installation of Bluefin LTS (xfs). To be frank, plain mutable xfs or ext4-based system seems to be even less prone to freezing, stuttering and exposing "wait or force quit" application dialogs.

Since rpm-ostree does not need CoW file system, and BTRFS seems to oversaturate the slow disks,
I would suggest creating an image with xfs (maybe even ext4) as the default file system even for the stable/GTS versions, as an option.

Best wishes to all,
Tom.

[castrojo]

I'd love to completely get off of it but we'd need to figure out a way to do it so it's a drop in replacement. Last attempt was here: #2916

I think there were lvm/growing issues?

[zilexa]

No issues here on a very old Lenovo laptop with a 128gb dramless ssd..
The idea of btrfs being slow is quite outdated. Look at Phoronix tests. And XFS.. that just benefits very large file systems. Bluefin LTS uses it.
I wouldn't stay on Bluefin if they really move away from btrfs. Its subvolume and snapshot functionality is ideal for home use (bluefin could leverage is much more).

[Mestar71]

Dear Mr Castro and Zilexa, Thanks for the quick replies and clarifications. No need to move away from btrfs, I just wanted to suggest an option that, according to my limited experience, might enhance the usability of an already excellent product on limited hardware. Since Mr Castro was kind to build an LTS version with xfs as default, that should be enough. Anyway, all Bazzite and Bluefin versions are delightfully designed and built operating systems. Of course, there is no stuttering with a fast nvme ssd. Thank you for paving the way into the future.

[passthejoe]

I am running on a SanDisk SSD Plus 480 GB SATA. It's considered a "budget drive," but the consensus is that it has a small amount of dram.

Performance with Bluefin has been great. I can "feel" that's it's not as good as the Samsung NVMe drive I used to run, but since my laptop with an NVMe slot died, I'm on SATA drives until I get new hardware.

[mrrfv]

I'm using an old 256 GB Micron SATA SSD for Bluefin (SSD model Micron_1100_MTFDDAK256TBN, OS image ghcr.io/ublue-os/bluefin-dx-nvidia-open:stable), and I can feel the stuttering when doing anything disk intensive, e.g., building Podman images or compiling shaders for and downloading Steam games. I haven't tested if switching from BTRFS is the solution, but a compromise could be feasibly made by letting advanced users choose before installing.

[JaviLib]

The problem is not BTRFS but the combination of your slow disk and a defautl setting in vm.dirty-* sysctl variables.
Just add this:

vm.dirty_background_ratio=1
vm.dirty_ratio=2

to /etc/sysctl.conf. You can apply the new values by calling sudo sysctl -f or rebooting.

And the system will not cache so much into ram and will become more responsive, at the expense of slightly less continuous writing performance.
Why this happens? When you have a lot of RAM, like 16 or 32GB, which is the normal today, the default value of 25% can be 4 or 8GB of RAM dedicated to cache, and when it flushes you notice a freeze. People using fast NVME won't notice a thing, or at most 1s of delay.

Note that this should not be the default, only people with low speed disks should reduce vm.dirty* variables, and only of they have a slow disk as their primary one (if you have a slow disk which is not your primary one, it is ok to let the defaults in place).

[Mestar71]

Thanks for the clear and sound explanation. I would Like to try it, but I already put Debian on ZFS on that disk, and it doesn't stutter at all (better caching defaults? ARC?). Meanwhile, you are perfectly right about btrfs working without noticeable stuttering on an NVME disk. In fact I've been using Bluefin as my primary system on that and could not be more satisfied. Thanks again, Tom

[dosubot]

Hi, @Mestar71. I'm Dosu, and I'm helping the bluefin team manage their backlog and am marking this issue as stale.

Recap

• You reported that BTRFS-based images can feel stuttery or freeze on slower SSDs/HDDs, while the XFS-based LTS image feels more responsive.
• Maintainers noted they’d like to move away from BTRFS eventually, but need a practical drop-in replacement and have run into growth/LVM constraints before.
• Other commenters suggested the behavior may be more related to slow-disk behavior and default vm.dirty_* settings than BTRFS itself.
• You later agreed the issue may be hardware-specific and said the XFS LTS image is sufficient for your needs.

Next Steps

• If this is still relevant on the latest version of the bluefin repository, please comment here to keep the discussion open.
• Otherwise, this issue will be automatically closed in 14 days.

Thanks for your understanding and contribution.