• 39 Posts
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Joined 3 年前
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Cake day: 2023年8月10日

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  • It’s easy. Mumble. Or the thing you used probably still works.

    But you see, people never actually seek a discord alternative. They want a discord alternative that includes all the features in one app that is also federated, AND end to end encrypted, and each one makes things vastly more technically challenging and resource intensive and then you want them together.

    A little secret: Matrix is much, much easier to host if you disable encryption and federation. Federation to many servers is the main performance killer, and “failed to decrypt message” will all disappear if you disable encryption.




  • If your software updates between stable releases break, the root cause is the vendor, rather than auto updating. There exist many projects that manage to auto update without causing problems. For example, Debian doesn’t even do features or bugfixes, but only updates apps with security patches for maximum compatibility.

    Crowdstrike auto updating also had issues on Linux, even before the big windows bsod incident.

    https://www.neowin.net/news/crowdstrike-broke-debian-and-rocky-linux-months-ago-but-no-one-noticed/

    It’s not the fault of the auto update process, but instead the lack of QA at crowdstrike. And it’s the responsibility of the system administrators to vet their software vendors and ensure the models in use don’t cause issues like this. Thousands of orgs were happily using Debian/Rocky/RHEL with autoupdates, because those distros have a model of minimal feature/bugfixes and only security patches, ensuring no fuss security auto updates for around a decade for each stable release that had already had it’s software extensively tested. Stories of those breaking are few and far between.

    I would rather pay attention to the success stories, than the failures. Because in a world without automatic security updates, millions of lazy organizations would be running vulnerable software unknowingly. This already happens, because not all software auto updates. But some is better than none and for all software to be vulnerable by default until a human manually touches it to update it is simply a nightmare to me.













  • This is not truly foolproof. Data can still be recovered from the spinning metal platter since it can theoretically be removed and put into a recovery device, even in a broken state.

    Im addition to that, hard drives/ssd’s sometimes have small flash memory chips, from which data can sometimes be recovered.

    If you want it to actually be unrecoverable then you have to actually ensure all parts thay store data are truly deleted/wiped, which is more than just the core platter. Or just use encryption and throw away the key, since all data going through the tiny OS on these devices will be encrypted. Or just store them forever in a vault.




  • Unless you are running at really large scales, or really small scales and trying to fit stuff that quite fit, memory compression may not be significant enough of an optimization to spend a lot of time experimenting a lot. But I’m bored and currently on an 8 GB device so here are my thoughts dumped out from my recent testing:

    Zram vs Zswap (can be done at hypervisor or at host):

    • One or the other is commonly enabled on many modern distros. It is a perfectly reasonable position to simply use the distro’s defaults and not push it any further
    • Zram has much, much better compression, but suffers from LRU inversion. Essentially after zswap is full, fresh pages (memory) goes to the swap instead. Since these pages will probably be needed, it will be slower to get them from the disk then to get them from zram.
    • Zswap has much, much worse compression but cold, unused pages are moved to swap automatically, freeing up space
    • I am investigating ways to get around the above. See my thoughts on this and other differences here: https://github.com/moonpiedumplings/moonpiedumplings.github.io/blob/main/playground/asahi-setup/index.md#memory-optimization

    Kernel same page merging (KSM) (would be done at hypervisor level) (esxi also has an equivalent feature called something different):

    • Only really efficient if you have lots of the same virtual machines
    • Used to overcommit (promise more ram than you physically have)
      • Dangerous, but highly cost saving. Many cheap VPS providers do this in order to save money. You can run four 8 GB vps on 24 GB of ram and take a semi-safe bet that not all of the memory will be used.

    In my opinion, the best thing is to enable zram or zswap at the virtual machine level and kernel same page merging at the hypervisor level, assuming you take into account and accept the marginal security risk and slightly weaker isolation that comes with KSM. There isn’t any point running zswap at two layers, because the hypervisor is just gonna spend a lot of time trying to see if it can compress stuff that’s already been compressed. Than KSM deduplicates memory across hosts. Although you may actually see worse savings overall if zram/zswap compression is only semi-deterministic and makes deduplication ahrder.

    I agree with the other commenter as well about zram being weird with some workloads. Like I’ve heard of I think it was blender interacting weirdly with zram since zram is swap, making less total memory available in ram, whereas zswap compresses memory. If you really need to know you gotta test.


  • That’s not quite true. Virtualbox is free but the extension pack is not. It says on the website that it’s under a different license.

    Just don’t get it from the website but from a distro’s repos instead and you’ll be fine. Distros usually patch out telemetry as well.

    But yeah, Oracle and similar schemes are why software installation is so restricted on corporate devices. It’s basically ransomware, freeware that people are willing to sue over.

    Edit: it should be noted that charging people for licensed software in a corporate environment is okay. I have heard stories of Oracle making people buy licences for EVERY computer even if only one person downloaded the software…