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Brendan Kenny

@brendankenny

Formerly lighthouse and web performance on Chrome. Open source, maths, Typescript nonsense, and bird stuff, apparently

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Latest posts by Brendan Kenny @brendankenny

How do you manage that in the car if they're too young for their own device? Apple music has nothing AFAICT, youtube music for all its faults has different accounts but is only switchable on the phone itself with multiple (slow) taps. When someone is begging to listen to Golden again I just give in

03.02.2026 16:05 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Not really, which is terrible. Also check for any paid subscriptions youtube offers now which might seem reasonable to someone and then be forgotten about :(

Theres browser extensions that will client-side filter, but otherwise delete history, try to reseed with better videos, and repeat in a month

24.01.2026 21:38 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
Auto-Throttle System Explained

Fill in the blanks in the following passage:


The ___ ___ of the ___ ___ is used for ___ to the ___ ___ during a ___ and continuing ___ later, with the ___ ___ as a ___ ___ (see the ___ ___ ___ ___ for more ___). This...

This passage describes the technical operation of an aircraft's Auto-Throttle (A/T) system, specifically the logic used during the takeoff and climb phases (common in Boeing 737 systems).

Here is the filled-in passage:

Completed Passage
The N1 mode of the auto-throttle is used for thrust to the N1 limit during a takeoff and continuing climb later, with the thrust levers as a visual reference (see the Auto Flight System Manual for more details). This allows engine-rated thrust to be automatically maintained so the pilot stays alert.

The A/T can annunciate when the airspeed sensed by the FMC is 84 knots. The annunciation for when the airspeed is 84 knots defaults to "THR-HLD", but can display a different mode if the takeoff roll occurs within a specified window.

Auto-Throttle System Explained Fill in the blanks in the following passage: The ___ ___ of the ___ ___ is used for ___ to the ___ ___ during a ___ and continuing ___ later, with the ___ ___ as a ___ ___ (see the ___ ___ ___ ___ for more ___). This... This passage describes the technical operation of an aircraft's Auto-Throttle (A/T) system, specifically the logic used during the takeoff and climb phases (common in Boeing 737 systems). Here is the filled-in passage: Completed Passage The N1 mode of the auto-throttle is used for thrust to the N1 limit during a takeoff and continuing climb later, with the thrust levers as a visual reference (see the Auto Flight System Manual for more details). This allows engine-rated thrust to be automatically maintained so the pilot stays alert. The A/T can annunciate when the airspeed sensed by the FMC is 84 knots. The annunciation for when the airspeed is 84 knots defaults to "THR-HLD", but can display a different mode if the takeoff roll occurs within a specified window.

Blanking some random but meaty github issue descriptions and MDN snippets is interesting. ChatGPT and Gemini identify the technical writing, but there's not enough there for them to nail down context.

ChatGPT keeps thinking things are about OpenAI KV caching, and Gemini thinks I'm asking about 737s

20.01.2026 23:12 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
To change a flat tire on a bike, first insert a tire lever between the tire and rim.
Next to that, insert a second lever and slide it along the outer edge of the rim.
You should now be able to remove the tire.
Gently pull the inner tube and attach the pump directly to the valve.
No adapter is needed.
Partially inflate the tube and put it back inside the tire,
then use the tire levers to roll the tire back onto the rim.
Finish inflating the tire to full pressure.

To change a flat tire on a bike, first insert a tire lever between the tire and rim. Next to that, insert a second lever and slide it along the outer edge of the rim. You should now be able to remove the tire. Gently pull the inner tube and attach the pump directly to the valve. No adapter is needed. Partially inflate the tube and put it back inside the tire, then use the tire levers to roll the tire back onto the rim. Finish inflating the tire to full pressure.

Activity - 47s
Thinking
Filling in bike repair instructions
Looks like I need to fill in blanks for instructions, possibly on removing a rear bike wheel. It says: "To ____ a ____ ____ on a ____." My guess is: "remove a rear wheel on a bike." The step "insert a tire lever between the tire and rim" seems pretty typical. Let's work with that!

Activity - 47s Thinking Filling in bike repair instructions Looks like I need to fill in blanks for instructions, possibly on removing a rear bike wheel. It says: "To ____ a ____ ____ on a ____." My guess is: "remove a rear wheel on a bike." The step "insert a tire lever between the tire and rim" seems pretty typical. Let's work with that!

Here's ChatGPT 5.2 thinking. Looks like it could be right? Pretty remarkable. I wish the thinking log would give any insight on how it made that first leap

20.01.2026 23:05 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Screenshot of text: "They can eat some poisonous and venomous prey with no ill effect, and will even team up to kill rattlesnakes. One will distract the snake by jumping and flapping while the other sneaks up and pins its head."

Screenshot of text: "They can eat some poisonous and venomous prey with no ill effect, and will even team up to kill rattlesnakes. One will distract the snake by jumping and flapping while the other sneaks up and pins its head."

clever girl

20.11.2025 16:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
Preview
Greater roadrunner - Wikipedia

That's a Greater roadrunner if you haven't spent time in southwesternish North America

20.11.2025 15:56 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
A grumpy looking bird with streaked brown and white feathers looks through a wire fence

A grumpy looking bird with streaked brown and white feathers looks through a wire fence

A roadrunner striding across a driveway, its spiky head crest raised and its long tail feathers sticking straight up in the air

A roadrunner striding across a driveway, its spiky head crest raised and its long tail feathers sticking straight up in the air

Did not recognize this grumpy muppet of a bird until it engaged its afterburners. I've never seen one inside city limits before!

20.11.2025 15:54 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Preview
Optimize long tasks ย |ย  Articles ย |ย  web.dev You've been told "don't block the main thread" and "break up your long tasks", but what does it mean to do those things?

It's right in the article :P

web.dev/articles/opt...

29.10.2025 15:24 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Anyways, the reason Michael Crichton probably thought T. Rex's vision was based on movement was because he didn't know the Opit was above the Brale but *behind* the โจกarl

24.10.2025 17:21 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
A ChatGPT conversation. ChatGPT asks "Would you like a labeled cutaway diagram showing where all these parts fit in the skull?", the user responds "Yes please", and ChatGPT responds with a cutaway diagram of a T. Rex head, with nonsense labels like two different brains, the eyeball labelled "Opit", and some partโ€”maybe the ocular muscles, I really have no ideaโ€”labelled "Brale".

A ChatGPT conversation. ChatGPT asks "Would you like a labeled cutaway diagram showing where all these parts fit in the skull?", the user responds "Yes please", and ChatGPT responds with a cutaway diagram of a T. Rex head, with nonsense labels like two different brains, the eyeball labelled "Opit", and some partโ€”maybe the ocular muscles, I really have no ideaโ€”labelled "Brale".

It cracks me up that a ChatGPT 5 conversation can be going ok, it was obviously RLHFed so hard to suggest a diagram when it would be genuinely useful, but apparently the second-order feedback "unless the resulting diagram is sloppy nonsense" wasn't incorporated

24.10.2025 17:17 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Preview
GitHub - tc39/proposal-defer-import-eval: A proposal for introducing a way to defer evaluate of a module A proposal for introducing a way to defer evaluate of a module - tc39/proposal-defer-import-eval

`import defer` will get you some of what you're looking for. The file is still loaded, but the synchronous parts of the module (and submodules) won't execute until first property access of the module namespace object.

github.com/tc39/proposa...

22.10.2025 16:59 ๐Ÿ‘ 4 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
Thought for 1m 30s

Youโ€™re right to call that out โ€” my earlier take was sloppy. Hereโ€™s the clean version.

Let
P := โ€œฯ€ + e is irrationalโ€
Q := โ€œthe Riemann Hypothesis (RH) is true.โ€

The claim is the disjunction P โˆจ Q. That is not a tautology; itโ€™s true iff at least one of P or Q is true. Right now:

We do not know whether ฯ€ + e is irrational. Itโ€™s a famous open problem. (A basic fact we can prove: at least one of ฯ€ + e or ฯ€e must be irrational, since if both were rational then ฯ€ and e would be roots of a quadratic with rational coefficients, contradicting their transcendence. But that doesnโ€™t tell us which one.) 
MathOverflow
Mathematics Stack Exchange
Wikipedia

We do not know whether RH is true; it remains unsolved. 
Wikipedia
arXiv

So the truth of โ€œฯ€ + e is irrational or RH is trueโ€ is currently unknown. It would be true in any world where either RH holds or ฯ€ + e is irrational; it would be false only in the (logically possible) world where RH is false and ฯ€ + e is rational โ€” a scenario not ruled out by current knowledge.

A handy logical rewrite:
P โˆจ Q is equivalent to (ยฌP) โ†’ Q. So the statement is the same as:

โ€œIf ฯ€ + e were rational, then RH would be true.โ€
No such implication is known, and thereโ€™s no known connection of that sort. 
Philosophy Stack Exchange
Mathematics LibreTexts

Bottom line: the statement is not โ€œformally true.โ€ Its truth value is unknown with our present mathematics.

Thought for 1m 30s Youโ€™re right to call that out โ€” my earlier take was sloppy. Hereโ€™s the clean version. Let P := โ€œฯ€ + e is irrationalโ€ Q := โ€œthe Riemann Hypothesis (RH) is true.โ€ The claim is the disjunction P โˆจ Q. That is not a tautology; itโ€™s true iff at least one of P or Q is true. Right now: We do not know whether ฯ€ + e is irrational. Itโ€™s a famous open problem. (A basic fact we can prove: at least one of ฯ€ + e or ฯ€e must be irrational, since if both were rational then ฯ€ and e would be roots of a quadratic with rational coefficients, contradicting their transcendence. But that doesnโ€™t tell us which one.) MathOverflow Mathematics Stack Exchange Wikipedia We do not know whether RH is true; it remains unsolved. Wikipedia arXiv So the truth of โ€œฯ€ + e is irrational or RH is trueโ€ is currently unknown. It would be true in any world where either RH holds or ฯ€ + e is irrational; it would be false only in the (logically possible) world where RH is false and ฯ€ + e is rational โ€” a scenario not ruled out by current knowledge. A handy logical rewrite: P โˆจ Q is equivalent to (ยฌP) โ†’ Q. So the statement is the same as: โ€œIf ฯ€ + e were rational, then RH would be true.โ€ No such implication is known, and thereโ€™s no known connection of that sort. Philosophy Stack Exchange Mathematics LibreTexts Bottom line: the statement is not โ€œformally true.โ€ Its truth value is unknown with our present mathematics.

To be fair, I forced it to use thinking mode to try again, and it admitted it was wrong. I was amused it based its answer only on searching MathOverflow and Wikipedia and not finding a mention of equivalency, though. I'm sure proving independence is difficult, but I was hoping for a little more :)

19.09.2025 20:14 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
That statement

ฯ€ + e is irrational or the Riemann Hypothesis is true

is formally true, but for a very boring logical reason rather than a deep number-theoretic connection.

Why itโ€™s true

A statement of the form (A or B) is true as long as at least one of A or B is known to be true.

In this case
A = ฯ€ + e is irrational.
B = The Riemann Hypothesis is true.

It is already known that ฯ€ + e is irrational or at least one of ฯ€ and e is transcendental (both are known to be transcendental individually).
In fact, it is an open problem whether ฯ€ + e is irrational (we donโ€™t know), but we do know that ฯ€ and e are irrational individually.
And more importantly, The logical form โ€œP or Qโ€ is always true if either part is true.

โ€œฯ€ + e is irrationalโ€ is not known to be true, but its negation (ฯ€ + e is rational) would be shocking and is widely believed to be false.

But hereโ€™s the key: Any statement of the form (unknown thing) OR (independent big conjecture) is trivially true unless both parts are false. Since the Riemann Hypothesis being false doesnโ€™t force ฯ€ + e to be rational, and ฯ€ + e being rational isnโ€™t known, the combined disjunction canโ€™t be proved false.

Whatโ€™s really going on

This is a classic joke statement in mathematics

People take an open problem (like ฯ€ + e irrationality). They take another famous open problem (Riemann Hypothesis).

Then they glue them together with an OR. The result is formally true (because if RH is true, the disjunction is true no matter what).

So the claim is not a genuine theorem about ฯ€ + e and RH being connected. Itโ€™s just a way of making a logically true but vacuous statement.

โœ… Bottom line:
Yes, the statement is true, but only because itโ€™s a trivial logical disjunction. It does not establish any relationship between ฯ€ + e and the Riemann Hypothesis.

Do you want me to walk you through why these kinds of true but useless statements are sometimes used in math (kind of like party tricks) or would you prefer I stick strictly to the logic?

That statement ฯ€ + e is irrational or the Riemann Hypothesis is true is formally true, but for a very boring logical reason rather than a deep number-theoretic connection. Why itโ€™s true A statement of the form (A or B) is true as long as at least one of A or B is known to be true. In this case A = ฯ€ + e is irrational. B = The Riemann Hypothesis is true. It is already known that ฯ€ + e is irrational or at least one of ฯ€ and e is transcendental (both are known to be transcendental individually). In fact, it is an open problem whether ฯ€ + e is irrational (we donโ€™t know), but we do know that ฯ€ and e are irrational individually. And more importantly, The logical form โ€œP or Qโ€ is always true if either part is true. โ€œฯ€ + e is irrationalโ€ is not known to be true, but its negation (ฯ€ + e is rational) would be shocking and is widely believed to be false. But hereโ€™s the key: Any statement of the form (unknown thing) OR (independent big conjecture) is trivially true unless both parts are false. Since the Riemann Hypothesis being false doesnโ€™t force ฯ€ + e to be rational, and ฯ€ + e being rational isnโ€™t known, the combined disjunction canโ€™t be proved false. Whatโ€™s really going on This is a classic joke statement in mathematics People take an open problem (like ฯ€ + e irrationality). They take another famous open problem (Riemann Hypothesis). Then they glue them together with an OR. The result is formally true (because if RH is true, the disjunction is true no matter what). So the claim is not a genuine theorem about ฯ€ + e and RH being connected. Itโ€™s just a way of making a logically true but vacuous statement. โœ… Bottom line: Yes, the statement is true, but only because itโ€™s a trivial logical disjunction. It does not establish any relationship between ฯ€ + e and the Riemann Hypothesis. Do you want me to walk you through why these kinds of true but useless statements are sometimes used in math (kind of like party tricks) or would you prefer I stick strictly to the logic?

I had a funny one when I saw a claim about ฯ€ + e and the Riemann hypothesis on the math subreddit that I hadn't heard. It was written in a way that suggested it might be a joke, though, so I though maybe I just didn't get it and asked GPT5. The first line is so intriguing! And then just nonsense

19.09.2025 19:57 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Small multiple - Wikipedia

small multiples! en.wikipedia.org/wiki/Small_m...

Looks fun, any shareable information about how "Create variants" is constrained? Is "give me more that looks like this" enough or does it need to go deeper?

19.09.2025 19:26 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

I vaguely remember the Wario game being ok? And Mario Tennis being so basic that it might as well have been pong. And yet, yes, the kid still in me who saved up allowance to rent one from Blockbuster for a weekend really wants one

12.09.2025 19:26 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

scheduler!

04.09.2025 22:50 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

Great answers!

05.03.2025 17:56 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

p8->p10 as a policy isn't quite the same (the PoDR isn't a fixed percentile of the distribution) but it's the rough equivalent to the old PoDR behavior. The p10 values also have the most manual tweaks, e.g. the actual p8 CLS is 0, but the p10 used is 0.1 to better recognize what CWV considers "good"

05.03.2025 17:56 ๐Ÿ‘ 3 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

and it was actually possible to score 100 (roughly 2% of the pages in HTTP Archive at the time would get 100 on a metric). But then we admitted everyone was thinking in terms of percentiles anyway, not the PoDR, so we kept the curves unchanged but converted it to be defined by the median and the p10

05.03.2025 17:56 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

p8->p10 is more convoluted because originally we specified the score curve by the median and "point of diminishing returns" (PoDR) (referenced in that screenshot), thinking of that as the more natural way to frame it, and adjusting it so that p5->PoDR so that it was both an aspirational curve

05.03.2025 17:56 ๐Ÿ‘ 3 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

p25->p50 is somewhat arbitrary, but evolved over the first few years of lighthouse to be a balance between reflecting reality and where, through many many perf audits, we judged the median site _could_ be with even moderate effort

05.03.2025 17:56 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

the CDF has the fastest growth in the middle, rewarding perf improvements where most sites are with the biggest score increases, and it ramps off as you get close to "great", in theory encouraging you to then look at other metrics for improvements (built in prioritization)

05.03.2025 17:56 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Most of these metrics are already log-normal (or log-normal enough) when looking at small or large scale (visits to a single page or visits aggregated over many origins), so it's a natural scoring curve model for the data, and it also has a couple of benefits:

05.03.2025 17:56 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

It's not a very pat answer because it evolved over years, but basically it's a balance between being based on real data, being aspirational (encouraging websites to be better than the typical website), rewarding perf improvements where it matters, and having good scores (and even 100s) be achievable

05.03.2025 17:56 ๐Ÿ‘ 5 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1

youtube.com/watch?v=dt8O...

16.01.2025 17:47 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
A somber Oppenheimer on the left with the label: Chrome removing the Performance Insights panel.
A delighted Barbie on the right with the label: Chrome adding even better insights to the Performance panel!

A somber Oppenheimer on the left with the label: Chrome removing the Performance Insights panel. A delighted Barbie on the right with the label: Chrome adding even better insights to the Performance panel!

Yes it's time to say good by to the Performance Insights panel and get back to having one Performance panelโ€”with the best of both worlds!

Read more from @brendankenny.bsky.social here:
developer.chrome.com/blog/insight...

27.11.2024 21:34 ๐Ÿ‘ 12 ๐Ÿ” 4 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1
Preview
J Perm I make videos so you can get faster! Check out the "Playlists" section on the main channel page. Business Email โ–บ dylanqwang@gmail.com How you can support me: Patreon โ–บ http://patreon.com/jperm Clot...

youtube.com/@JPerm does really good explanations, I've found. I've never tried the megaminx, but looks like he has at least one video on it: youtube.com/watch?v=oVRo...

23.11.2024 23:54 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0