Readit News logoReadit News
gfv commented on In defence of swap: common misconceptions (2018)   chrisdown.name/2018/01/02... · Posted by u/jitl
heavyset_go · 3 months ago
Maybe I'm just insane, but if I'm on a machine with ample memory, and a process for some reason can't allocate resources, I want that process to fail ASAP. Same thing with high memory pressure situations, just kill greedy/hungry processes, please.

Like something is going very wrong if the system is in that state, so I want everything to die immediately.

gfv · 3 months ago
sysctl vm.overcommit_memory=2. However, programs for *nix-based systems usually expect overcommit to be on, for example, to support fork(). This is a stark contrast with Windows NT model, where an allocation will fail if it doesn't fit in the remaining memory+swap.
gfv commented on Boeing 787s must be reset every 51 days or 'misleading data' is shown (2020)   theregister.com/2020/04/0... · Posted by u/jakey_bakey
withinboredom · a year ago
This is incorrect. Very incorrect and disastrously so. Drop 0.3 in here: https://www.h-schmidt.net/FloatConverter/IEEE754.html

You can also drop 524535643, an integer clearly less than 2^53 and is off by 5.

This is even seen here:

    #include <stdio.h>

    int main() {
            float b = 524535643.0f;
            printf("%f", b);
            return 0;
    }
output: 524535648.000000

gfv · a year ago
I was talking specifically about double-precision floats. Single-precision floats can represent every integer up to +-2^24.
gfv commented on Boeing 787s must be reset every 51 days or 'misleading data' is shown (2020)   theregister.com/2020/04/0... · Posted by u/jakey_bakey
Dylan16807 · a year ago
Previous: https://news.ycombinator.com/item?id=22761395 https://news.ycombinator.com/item?id=33233827

More interesting, a root cause analysis: https://news.ycombinator.com/item?id=33239443 https://ioactive.com/reverse-engineers-perspective-on-the-bo...

The 47 bit timestamp at 32MHz would explain the duration (Though not why it isn't 33MHz?).

gfv · a year ago
I have a way simpler explanation. IEEE 754 double can only represent integers up to 2^53 without precision loss, so if you naively average two numbers greater than 2^52, you get an erroneous result.

It just so happens that 2^52 nanoseconds is a little bit over 52 days.

I've seen the same thing with AMD CPUs where they hang after ~1042 days which is 2^53 10-nanosecond intervals.

gfv commented on Music Industry's 1990s Hard Drives Are Dying   arstechnica.com/gadgets/2... · Posted by u/m463
ftio · a year ago
Other than continuously copying files to new media every so often, are there reliable digital mechanisms for long-term storage (say, 50 years)?
gfv · a year ago
Yes, you can chuck your SSD into a freezer. Data retention time increases exponentially in lower temperatures, so keeping it in a regular +4C fridge is enough to extend retention by decades.

Just remember to heat up the disk before writing and after storage.

https://www.ni.com/en/support/documentation/supplemental/18/...

gfv commented on Why not parse `ls` and what to do instead   unix.stackexchange.com/qu... · Posted by u/nomilk
Aerbil313 · 2 years ago
Do you recommend it? I feel like I'd get RSI from pressing shift when using it. https://learn.microsoft.com/en-us/powershell/module/microsof...
gfv · 2 years ago
Powershell is mostly case-insensitive, and most of the core cmdlets have short aliases. Try `Get-Alias` (or `gal`) to learn more.
gfv commented on Experience with SQLite as a Store of Files and Images   sqlite.org/forum/forumpos... · Posted by u/thunderbong
Repulsion9513 · 2 years ago
> if the blobs (e.g. images) in the DBs are static, and transactions are read only/writes happen infrequently, then having all your blobs in one SQLite DB makes for an insanely easy backup strategy

Does it? Suddenly instead of just backing up the whole database you have to do delta backups which can make it quite a bit more difficult...

gfv · 2 years ago
You can use streaming WALs, like Litestream does. It is a pretty simple way to do incremental backups.
gfv commented on British Post Office Scandal   en.wikipedia.org/wiki/Bri... · Posted by u/dragonbonheur
sdflhasjd · 2 years ago
Is there any actual technical report of what's wrong with the Horizon system? This feels like a weirdly long Wikipedia article that only touches on legal points and that somewhat lacks in real substance.
gfv · 2 years ago
Yes, there is the technical appendix to the 2019 judgement.

https://www.jfsa.org.uk/uploads/5/4/3/1/54312921/technical_a...

gfv commented on Origins of J   github.com/kelas/ooj... · Posted by u/tosh
kstrauser · 2 years ago
“…and that’s why we have code formatters.”

That’s neat and impressive. I’m glad I’m not required to read or understand it.

gfv · 2 years ago
It really doesn't help that it's written in ancient K&R C, but if you spend ten or so minutes just staring at it, familiar shapes and patterns start to appear. (Give it a try!)

Incidentally, it's in line with how APL code looks like an alien artifact at first, but you get used to it fast if you have spatial reasoning to wrap your head around reshaping and transposing.

gfv commented on How thermal management is changing in the age of the kilowatt chip   theregister.com/2023/12/2... · Posted by u/rntn
ksec · 2 years ago
Assuming the upcoming Zen 5c was capped at 192 Core because of Bandwidth and not Thermal. We could have had 256 Core + IOD ( 70W ), if every core were to use 3.6W that is nearly 1000W for the CPU Socket.

In a 2U 2Node system, this is a potential of 1024 vCPU in a single server.

gfv · 2 years ago
In datacenters, you're mostly limited by the power (and thus cooling). Most commercial DCs only let you use up to about 10kW per rack. For standard 40U racks it's just 250W/RU, give or take.

There are niche expensive datacenters with higher power density, but as it stands, exotic multi-kW hardware at scale makes sense if you either save a ton on per-node licensing, or you need extreme bandwidth and/or low latency.

u/gfv

KarmaCake day258July 27, 2013View Original