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ZFS Profiling on Arch Linux

binwang.me

183 points by wb14123 2 years ago · 33 comments

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nisa 2 years ago

Another fix for that is to switch the ZFS license to GPL before building:

Just put this line:

sed -i "s/CDDL/GPL/g" META

in the prepare() section of the PKGBUILD.

This will use the in-kernel FPU functions for cryptography and other things like raidz calculations that got EXPORT_SYMBOL_GPL'ed later if the original plumbing is still in the codebase. It's probably not offically recommend and I'm not sure how much these codepaths are tested anymore but I assume that quite a few people that don't need to redistribute anything but need the performance use a hack like this or something similiar. It works fine for me.

Personally I lost a ton of respect for the Linux kernel developers after introducing that kernel fpu EXPORT_SYMBOL_GPL thing and backporting it to all kernels and Linus badmouthing ZFS and somehow assuming Oracle is still involved in OpenZFS which is mostly FreeBSD and some sponsors spread out over the world but not related to Oracle.

InvaderFizz 2 years ago

This is a great read. It explains in detail the process of enabling debug symbols and using perf to root cause a performance issue.

I've never done this type of work, but probably will in the future now that I have an example to follow.

tjoff 2 years ago

It is refreshing to see the author explain how and why all the pieces were gathered. Most guides/instructions/bug-reports only lists the end result, omitting information that helps the reader to get a better understanding and be better equipped to solve related issues.

predmijat 2 years ago

On Arch, zfs-linux package has an exact version of linux as a dependency. linux package gets updated fairly often, and by the time zfs-linux package catches up, linux is already on a newer version and you are unable to upgrade.

Sometimes it takes quite a while before those two are in sync and you can upgrade your system.

  • tobias2014 2 years ago

    In addition to the other comments: you could use the zfs-dkms package which builds it from source on every update

  • mzi 2 years ago

    If you reorder your repositories so the zfs repository comes before the default one in the configuration you won't have that problem.

  • 79a6ed87 2 years ago

    Targetting the linux-lts package as a dependency instead of linux should reduce the impact of this issue

  • enormousness 2 years ago

    You can install the specific older version of the Linux package that the zfs package needs. You can also pin it so it won't get updated by regular upgrades.

  • hnlmorg 2 years ago

    Is there lts kernel support for zfs-linux? I found I had to switch to the lts kernel on an Arch gaming rig because of issues with Nvidia drivers.

sneak 2 years ago

I heard a rumor that ZFS native encryption is somewhat abandoned by its maintainer following it having landed in the release, that it was one person and they moved on/lost interest. I don’t know if this is true or not.

I’m still using ZFS on LUKS2 for now, given the issues like this. (You also can’t specify multiple keys in ZFS native encryption.)

b33j0r 2 years ago

Channelling Erik Dubious: “it’s ok, you see the error message, and you navigate to etsy.

This config we find is the answer. I lean into neovim this time, today, because it’s all a lessons. And then we type update, and it’s all okay!”

The thing he humbly leaves out is “why aren’t you an arcolinux fanboy yet!?”

  • b33j0r 2 years ago

    I am like disturbed that two people thought complimenting Erik’s work was worth a downvote. Who the heck hates nice people so much to spend that.

    I’m an arch contributor, your’re barking up the wrong tree.

    • dfc 2 years ago

      I think the downvotes had more to do with people not knowing what/who you are referring to. Without the context that you have your comment seems like word salad.

    • Modified3019 2 years ago

      Perhaps it's a non-native english speaker thing, but it's very hard to understand your prior post.

      It looks like a bot post, from the time before AI generation actually became good. The post appears like random disconnected concepts are just thrown together with no clear context or relevancy to the topic of debugging ZFS.

      • b33j0r 2 years ago

        You are correct. I really wasn’t aware that talking about famous linux people was such an inside joke in this forum. My bad (sincerely.)

        • kwk1 2 years ago

          I have a feeling this person is not all that famous, and it may not have helped if you meant Erik Dubois. Searching for "Erik Dubious" didn't yield much, but neither did the correct (?) search

          Edit: while Twitter followers is not a great metric for popularity, I wouldn't expect someone with 788 followers to be a household name

          • b33j0r 2 years ago

            It was indeed an autocorrect fail. I thought someone would know what I was talking about. I can see now how linguistically ambiguous my comment was. Yes, I was promoting arcolinux. It's a fun and educational arch derivative. I really didn't know it was so obscure. I did not intentionally misspell the name dubois as dubious. That was my device, and my inattention ;)

        • dfc 2 years ago

          I had never heard of him before. I'm curious what he is he famous for?

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