Live data from Hacker News

Linux 5.10 BTRFS performance regression

reddit.com

1–10 of 202 posts

Re: Linux 5.10 BTRFS performance regression

#3
A link to a few Reddit comments? This is just like how 9gag link to Reddit that link to Facebook that link to ........ that link to reddit and so on.

Now HN really is at Reddit level. Now we just need a link to HN in the comments.

Re: Linux 5.10 BTRFS performance regression

#4
post #2

Assuming it can be fixed in a 5.10.x patch release, it's a rather minor story - a bug that is quickly found after release and fixed, hopefully. It will be investigated: https://marc.info/?l=linux-btrfs&m=160869337604422&w=2

The problem with btrfs is that it has quirks like that (and worse, much worse) all the time.

Re: Linux 5.10 BTRFS performance regression

#6
post #4
post #2

Assuming it can be fixed in a 5.10.x patch release, it's a rather minor story - a bug that is quickly found after release and fixed, hopefully. It will be investigated: https://marc.info/?l=linux-btrfs&m=160869337604422&w=2

The problem with btrfs is that it has quirks like that (and worse, much worse) all the time.

Why does btrfs have those issues compared to other filesystems? I'd love to use btrfs too. Note that I deeply respect people who can write such complicated code, which I couldn't.

Would Rust solve the non-speed issues? Rust-in-kernel discussion from August: https://lwn.net/Articles/829858/

Re: Linux 5.10 BTRFS performance regression

#7
post #6
post #4

Earlier quoted context omitted.

The problem with btrfs is that it has quirks like that (and worse, much worse) all the time.

Why does btrfs have those issues compared to other filesystems? I'd love to use btrfs too. Note that I deeply respect people who can write such complicated code, which I couldn't. Would Rust solve the non-speed issues? Rust-in-kernel discussion from August: https://lwn.net/Articles/829858/

Please understand that the rust memory and thread security mainly applies to "normal" applications.

In kernel, you can run a privileged cache or mmu instruction or a write to some magical memory position and all the sudden the "normal" rules don't apply anymore.

(But I think there are other parts of rust that are nice to have in kernel or any complex software).

Re: Linux 5.10 BTRFS performance regression

#9
post #5

The ratio of bad to good posts about BTRFS always made me wonder why anyone would roll with it. Don’t put your fs in crazy.

The ratio of bad to good posts has always stunned me too. But for the opposite reason.

The linked post explains that there is a performance regression in a very rare and specific usecase: creating 100k files in a short span of time. And I'm not talking about unpacking boost, that's not enough files.

Additionally, it will be fixed before any distro packages it. (even Arch is still on 5.9.14.)

On the other hand btrfs got rather impressive speedups for fsync https://www.phoronix.com/scan.php?page=news_item&px=Linux-5....

Why are people making so much noise instead of just reporting the bug upstream when stuff goes wrong with btrfs, and why do we hear so little about the positive impact of new improvements. Almost like the people behave like customers of commercial operating systems. :-)

Re: Linux 5.10 BTRFS performance regression

#10
post #6
post #4

Earlier quoted context omitted.

The problem with btrfs is that it has quirks like that (and worse, much worse) all the time.

Why does btrfs have those issues compared to other filesystems? I'd love to use btrfs too. Note that I deeply respect people who can write such complicated code, which I couldn't. Would Rust solve the non-speed issues? Rust-in-kernel discussion from August: https://lwn.net/Articles/829858/

I sincerely hope you are joking but I realize this mindset is quite common these days, so let me reiterate: Rust does not magically solve problems for you. Btrfs has a lot of issues and some of them may well be of the not possible in Rust sort, but I'm quite sure most of them are not and there is nothing Rust can fix about them. Rewriting a 13 years old and very complex thing in another language is a massive effort and a big opportunity for introducing some more, possibly worse bugs along the way.

EDIT: also see panpanna's comment

Post reply on HN