My machines versus the Fedora selinux-policy-targeted package
I upgrade Fedora on my office and home workstations through anonline upgrade with dnf ,and as part of this I read (or at least scan) DNF's output to lookfor problems. Usually this goes okay, but DNF5 has a generalproblem with script output and whenI did a test upgrade from Fedora 41 to Fedora 42 on a virtualmachine, it generated a huge amount of repeated output from a scriptrun by selinux-policy-targeted, repeatedly reporting "Old compiledfcontext format,
Some notes on (Tony Finch's) exponential rate limiting in practice
After yesterday's entry where I discovered it , I went and implemented Tony Finch's exponential rate limiting for HTTP request rate limiting in DWiki , the engine underlying this blog , replacing the more brute force and limitedversion I had initially implemented. I chose exponential ratelimiting over GCRA or leaky buckets because I found it mucheasier to understand how to set the limits (partly because I'msomewhat familiar with the whole thing from Exim). Exponential ratelimiting needed me to pick a period of time and a
I don't know how to implement proper ratelimiting (well, maybe I do now)
In theory I have a formal education as a programmer (although itwas a long time ago). In practice my knowledge from it isn'tcomprehensive, and every so often I run into an area where I knowthere's relevant knowledge and algorithms but I don't know whatthey are and I'm not sure how to find them. Today's area is scalablerate-limiting with low storage requirements .
Suppose, not hypothetically, that you want to ratelimit a collectionof unpredictable sources and
ZFS snapshots aren't as immutable as I thought, due to snapshot metadata
If you know about ZFS snapshots, you know that one of their famousproperties is that they're immutable; once a snapshot is made, itsstate is frozen. Or so you might casually describe it, but thatdescription is misleading. What is frozen in a ZFS snapshot is thestate of the filesystem (or zvol) that it captures, and only that.In particular, the metadata associated with the snapshot can andwill change over time.
(When I say it this way it sounds obvious, but
How I think OpenZFS's 'written' and 'written@<snap>' dataset properties work
Yesterday I wrote some notes about ZFS's 'written' dataset property , where the short summary is that'written' reports the amount of space written in a snapshot (ie,that wasn't in the previous snapshot), and 'written@ ZFS snapshots and filesystems have a ' written 'property, and a related ' written@snapshot one. These are documented as: (Apparently In theory, a website that wanted to play video or audio could throwin a '< video controls ...>' or '< audio controls ...>' element in the HTML of the page and be done with it.This would make handling playing media simple and blocking autoplayreliable; you'd ignore the autoplay element and the person using the browser would directly triggerplaying media by interacting with things that the browser directlycontrolled and so the browser could know for sure that a person haddirectly One of the things I've come to believe in (although I'm not consistentabout it) is that we can't expect people to pick software that is'good' in a technical sense. People certainly can and do picksoftware that is good in that it works nicely, has a user interfacethat works for them, and so on, which is to say all of the partsof 'good' that they can see and assess, but we can't expect peopleto go beyond One of the things our Prometheus environment has is a notion of different sortsof alerts, and in particular of less important alerts that shouldgo to a subset of people (ie, me). There are various reasons forthis, including that the alert is in testing ,or it concerns a subsystem that only I should have to care about,or that it fires too often for other people (for example, a rebootnotification for a machine we routinelyreboot). For historical reasons, there are at least four It's not news that full speed NVMe disks are extremely fast, aswell as extremely good at random IO and doing a lot of IO at once.In fact they have performance characteristics that upset generalassumptions about how you might want to design systems, at leastfor reading data from disk (for example, you want to generate a lotof simultaneous outstanding requests, either explicitly in yourprogram or implicitly through the operating system). I'm not surehow much write bandwidth normal NVMe drives can really deliver
Some notes on OpenZFS's 'written' dataset property
written written @snapshot
Why Firefox's media autoplay settings are complicated and imperfect
We can't expect people to pick 'good' software
Our too many paths to 'quiet' Prometheus alerts
Could NVMe disks become required for adequate performance?
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