The bug made it to the kernel mailing list where some Intel people looked into it and confirmed there is a bug. There is a problem where is the kernel allocation logic was capped to 8 cores, which leaves a few percent of performance off the table as the number of cores increase and the allocation is less and less optimal.

It's classic tragedy of the commons. CPU have got so complicated, there may only be a handful of people in the world who could work and comprehend a bug like this.

GPU and CPU manufacturing is the same thing, same node, same result. GPU is always maximizing perf/power ratio because it's embarrassingly parallel, leaving no room to game the benchmark. CPU can be gamed by having a single fast core, that drops performance in half as soon as you use another core.

Yep, the scheduling has been a problem for a while. There was an amazing article few years ago about how the Linux kernel was accidentally hardcoded to 8 cores, you can probably google and find it.

IMO the most interesting problem right now is the cache, you get a cache miss every time a task is moving core. Problem, with thousands of threads switching between hundreds of cores every few milliseconds, we're dangerously approaching the point where all the time is spent trashing and reloading the CPU cache.

The core density is bullshit when each core is so slow that it can't do any meaningful work. The reality is that Intel is 3 times behind AMD/TSMC on performance vs power consumption ratio.

People would be better off having a look at the high frequency models (9xx5F models like the 9575F), that was the first generation of CPU server to reach ~5 GHz and sustain it on 32+ cores.

Putting more cores is just another desperate move to play the benchmark. Power is roughly quadratic with frequency, every time you fall behind competition, you can double the number of cores and reduce the frequency by 1.414 to compensate.

Repeat a few times and you get CPU with hundreds of cores, but each core is so slow it can hardly do any work.

I don't know how possible it is to find a really bad cable (untwisted) and it might work on a short length anyway. (Your 1980s office cabling must have been 8 wires if you were able to get gigabit later, so it was far beyond basic phone wires or Cat1 from the time).

Short version: The UK regulator OFCOM defines ultrafast internet as 30 Mbps download speed. That's why UK internet providers (openreach and related) have deals starting as low as 30 Mbps and they can't be arsed to provide a faster speed (unless you pay £££).

You can see that on the HellDivers screenshot, it takes 20 seconds to reach 500 Mbps, because TCP takes a while to adjust the bandwidth and is very conservative. TCP and home computers are not designed to make use of gigabit connections.

Incidentally, this is likely to be the furthest room on the furthest floor, so it can be a good place to add a wifi access point for coverage.

You're actually wrong on all of that ^^

The cables actually have a rating to say what they are suitable to. See the markings on the cable: category Cat5/Cat5e/Cat6 + frequency range 100/250 Mhz + insulation UTP/FTP/STP/mix.

Ethernet cards don't negotiate, they typically only check whether the pairs can transmit any signal. You could end up in a situation where they go for gigabit and it doesn't work well.

Fortunately, the main issue for signal transmission is loss over distance. Ethernet is designed to work over 100m every time in a noisy industrial environment. You've got a pretty good chance for it to work on a short run, even with poor cables.

The alternatives being discussed ADSL/VDSL/G.hn actually detect the capability of the medium and adjust the transmission rates and frequency to give the maximum possible speed. IMO they are much more advanced technologically and much more interesting. (Ethernet is doing exactly 250 Mbps on one pair, G.hn can do up to 1700 Mbps on the same pair, automatically adjusted, the article is getting 1300 Mbps which is insane!)

Otherwise it's just your WiFi being patchy. I think Steam is doing "friendly" bulk download, it slows down before the connection is saturated, to avoid disconnecting your wife/mum/siblings watching Youtube or on a videoconference.

I don't think there is anything too fancy compared to a DSLAM. It's just that DSLAM are low-frequency long-range by design.

Numbers for nerds, on top of my head:

* ADSL1 is 1Mhz 8Mbps (2 kilometer)

* ADSL2 is 2Mhz 20Mbps (1 kilometer)

* VSDL1 is 15Mhz 150Mbps (less than 1 kilometer)

* Gigabit Ethernet is 100Mhz over four pairs (100 meters). It either works or it doesn't.

* The G.hn device here is up to 200 MHz. It automatically detects what can be done on the medium.

It's really not that simple when you realize that the average UK flat has 3+ sockets and the average house has 5+ sockets (speaking from my own experience). Some daisy chained and some direct.

Besides, a lot of people are renting and cannot touch their wire.

> One peculiar thing from the UK: Internet providers don’t truly offer gigabit internet. They have a range of deals like 30 Mbps – 75 Mbps – 150 Mbps – 300 Mbps – 500 Mbps – 900 Mbps, each one costing a few more pounds per month than the last.

Gigabit is so much more expensive (obviously it's gone down a lot). In London 2016, I had ADSL broadband at 16 Mbps for £12/month. That building didn't have fiber at the time. When fiber finally happened... it started as 30 Mbps fiber for so much more money.

Comments URL: https://news.ycombinator.com/item?id=46742362

Points: 480

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Comments URL: https://news.ycombinator.com/item?id=46730274

Points: 4

# Comments: 0

I will reply to this comment because it's the easier to address, you're really hitting on the main misconception :D

It is incorrect to think that the DMCA form is only valid for copyright.

You need to contact the other party to start a legal dispute, you can do so by any available communication channels. The website is hidden behind cloudflare which purposefully hides the identity of the author and prevents any contact, except via a DMCA form. Burger King filled the DMCA form to get in touch with the author. It's merely a mean to legally contact the author and start a dispute, in the absence of better options.

It worked, cloudflare forwarded the form to the author (and the author decided to take down the article on their own). I really can't think of any reason why it would not be considered a reasonable and legitimate use of the form. All the better because it's an official legal form.

You don't publish because you don't want to cause harm and you don't want to be liable for it.

You need to realize that vulnerabilities don't exist in a vacuum. They grant access to computer systems that control the life of people (millions of people) including their personal information, passwords, passport photos, card numbers, jobs, paychecks, transportation, food, etc... which is very likely to cover yourself, your mom, your family, your friends as you deal with larger companies.

When you publish a vulnerability, it will immediately be used by bad actors that intend to cause harm to all these people, including employees and customers.

Comments URL: https://news.ycombinator.com/item?id=43524557

Points: 23

# Comments: 9