cultural reviewer and dabbler in stylistic premonitions

  • 62 Posts
  • 119 Comments
Joined 3 years ago
Cake day: January 17th, 2022
  • Arthur Besse@lemmy.mlto196@lemmy.blahaj.zone•firefox ruleEnglish
    5·
    6 days ago

    I work in tech, and I don’t understand people’s obsession with having all their RAM free at all times.

    If you don’t use it, why do you have it?

    Windows (not the best OS, but the one I know the most about), will lie to you about how much memory you have that’s free. It puts data in RAM as cache. In the event you need that data, it’s already loaded in RAM. Usually this is stuff like DLLs and executables for programs.

    There’s a difference between “free” memory, and “available” memory.

    Linux and macOS do the same, although I wouldn’t call it lying per se :)

    There is certainly a lack of understanding of the difference between free and available RAM. TLDR: yes, free RAM is indeed wasted RAM.

    If you actually have a lot of free RAM, it’s probably because you either booted or freed a lot of RAM very recently. After using your computer for a while, most of your available RAM should not be free but rather being used for page cache and other caches.

    After a program has just read and/or written more data from disk than will fit in available RAM, the kernel’s page cache (which is typically the bulk of that not-free-but-available memory) should be mostly populated by the most recent of those operations. This means that if that program (or any other program) reads those files again, before they are evicted from cache by other things, they will not need to wait for the disk and will get them back much faster.

    However, managing all of this is the kernel’s job, and the not-free-but-available RAM being used for page cache is not (in any OS, as far as I know, though I mostly know Linux) attributed to the program(s) responsible for putting things there.

    So, when people are complaining about an application using 40% of their RAM it is not necessarily due to them misunderstanding free-vs-available RAM. The used number for an application does not include the portion of the system’s not-free-but-available RAM which the application is also responsible for occupying.

    (If you want to know which programs and/or which files are responsible for occupying your page cache… on Linux at least, it is not really possible without instrumenting your kernel. The kernel is just tracking blocks. There several tools which will let you see which blocks of a given file are cached, but there isn’t a reverse mapping from blocks to files.)

  • Arthur Besse@lemmy.mlMtoLinux@lemmy.ml•Use Rsync Daemon with SSH !? [ solved ]English
    2·
    9 days ago

    (disclaimer: this information might be years out of date but i think it is still accurate?)

    SSH doesn’t have a null cipher, and if it did, using it still wouldn’t make an SSH tunnel as fast as a TCP connection because SSH has its own windowing mechanism which is actually what is slowing you down. Doing the cryptography at line speed should not be a problem on a modern CPU.

    Even though SSH tunnels on your LAN are probably faster than your internet connection (albeit slower than LAN TCP connections), SSH’s windowing overhead will also make for slower internet connections (vs rsync or something else over TCP) due to more latency exacerbating the problem. (Whenever the window is full, it is sitting there not transmitting anything…)

    So, to answer OP’s question:

    • if you want to rsync over SSH, you usually don’t need a daemon (or to specify --rsh=ssh as that is the default).
    • if you the reason you want to use the rsync daemon is performance, then you don’t want to use SSH. you’ll need to open a port for it.
    • besides performance, there are also some rsync features which are only available in “daemon mode”. if you want to use those, you have at least 3 options:
      • open a port for your rsync daemon, and don’t use SSH (bonus: you also get the performance benefit. downside, no encryption.)
      • setup an SSH tunnel and tell the rsync client it is connecting to a daemon on localhost
      • look at man rsync and read the section referred to by this:

        • The remote-shell transport is used whenever the source or destination path contains a single colon (:) separator after a host specification. Contacting an rsync daemon directly happens when the source or destination path contains a double colon (::) separator after a host specification, OR when an rsync:// URL is specified (see also the USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION section for an exception to this latter rule).

    HTH.

  • Arthur Besse@lemmy.mlOPMtoMemes@lemmy.ml•Mystery solved
    8·
    12 days ago

    I don’t want to access the Sun, what’s the TLDR?

    The TLDR is that the article doesn’t explain that the reason it is circular (not to mention “invincible”) is because that is the defined boundary of a national park:

    A LONELY volcano surrounded by a dark green forest dubbed the “goblin forest” has left explorers baffled by its perfectly circular appearance.

    here is a copy+paste of firefox's reader view of the article

    thesun.co.uk Mystery of perfectly circular invincible ‘Goblin Forest’ surrounding a sacred volcano in the land of Hob… Vera Demertzis 4–6 minutes

    The lonely, almost perfect conical volcano sits in an eerily circular forest

    Published: 18:54, 19 Nov 2024
Updated: 1:26, 20 Nov 2024

    A LONELY volcano surrounded by a dark green forest dubbed the “goblin forest” has left explorers baffled by its perfectly circular appearance.

    Sitting at 8,261ft tall, with a six mile radius , Mount Taranaki is the second highest peak on New Zealand’s North Island.

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    The perfectly circular Goblin Forest surrounds the Mount Taranaki volcano

    6 The perfectly circular Goblin Forest surrounds the Mount Taranaki volcanoCredit: NASA/Landsat 8

    The Goblin Forest is overgrown with twisted and deformed trees

    6 The Goblin Forest is overgrown with twisted and deformed treesCredit: Getty Images - Getty

    The stunning mountain featured as Mt Fuji in The Last Samurai and Mount Doom in a panoramic shot

    6 The stunning mountain featured as Mt Fuji in The Last Samurai and Mount Doom in a panoramic shotCredit: Getty

    The iconic Mount Taranaki volcano in New Zealand’s North Island is so striking, that it once doubled as Mount Doom in the “Lord of the Rings” and Mt Fuji in “The Last Samurai”.

    The lonely, almost perfect conical volcano sits in an eerily circular forest containing thousands of warped and ancient kamahi trees fighting for space.

    The trees are extremely twisted and deformed as a result of having to grow over and around the fossilised remains of trees that were destroyed in past eruptions.

    The trees are also covered in hanging mosses and liverworts, adding to its creepy appearance. Read more world news

    In 2017, the mountain attained a new level of protection when it was granted the same legal rights as a person.

    The status is an acknowledgment of the Indigenous Māori people’s relationship.

    Despite its perfectly circular appearance from above, the volcano has a history of dramatic change.

    The mountain side has collapsed and rebuilt 16 times, with each cycle sending large debris avalanches down its flanks from past eruptions since it first formed around 135,000 years ago.

    Steep slopes, loose sediments, high rainfall rates, and buried faults all contribute to its tendency to collapse.

    The iconic volcano last erupted 200 years ago, but is still considered active and occasionally spits out mudflows.

    Researchers believe that there’s a 30-50 per cent chance of another major eruption in the next 50 years, potentially effecting more than 100,000 people.

    Recently, a hiker was rescued from the clutches of the mysterious mountain.

    The hiker had called for help after he realised he was going into hypothermia.

    He had been on a day trail run when he was caught out by weather in very cold temperatures, local police said.

    A police spokesperson added: "Unprepared for the local conditions, the solo traveller was running out of food, water, and phone battery, and was 1400 metres up the mountain when he phoned for an ambulance.

    “Taranaki Police Search and Rescue, the Taranaki Rescue Helicopter and alpine cliff rescue members were scrambled in an effort to get the man off the mountain as quickly as possible.”

    Mount Taranaki isn’t the only perfectly circular mystery.

    A mysterious spinning island shaped like a perfect circle has left explorers baffled for years.

    Known as “The Eye” the uninhabited patch of overgrown vegetation floats around a crystal clear lake in Argentina slowly moving each day.

    The bizarre natural phenomenon sits in the swampy river of Parana Delta in Buenos Aires and it has left many experts stumped over why or how it moves so freely.

    Those lucky enough to have travelled to the island say it is almost a perfect circle due to the movement of the land mass.

    Overtime the corners of the lake have managed to rub against the island as it moves and eroded itself into 360 degree smooth outlines.

    Incredible aerial footage shows the 387ft spherical island, known locally as El Ojo, surrounded by a crescent of water.

    The leading reason as to why the island floats is due to a natural process that sees water currents slowly shape and rotate the island in strong currents.

    A few other shocking theories suggest it may have belonged to an ancient civilisation. READ MORE SUN STORIES

    Or a more bizarre theory that claims the incomprehensible perfection and isolated location may be linked to extraterrestrial life.

    Some say El Ojo could be a hidden UFO base but so far no evidence has backed this up.

    Hanging moss and liverwort give the trees a creepy appearance

    6 Hanging moss and liverwort give the trees a creepy appearanceCredit: Getty Images - Getty

    A hiker was recently rescued from the mountainside

    6 A hiker was recently rescued from the mountainsideCredit: Getty Images - Getty

    The active volcano occasionally spews mudflow but hasn’t erupted in more than 200 years

    6 The active volcano occasionally spews mudflow but hasn’t erupted in more than 200 yearsCredit: Getty

  • Arthur Besse@lemmy.mltoPolitical Memes@lemmy.world•Russia has never wanted peace
    1·
    16 days ago

    I was referring to the “Zelensky actually changed this” part of the message I was replying to. What do you think that means, if not that they forgot when he became president?

    The only other explanation I can imagine is that maybe they meant to imply that Poroshenko was in Putin’s pocket, but that seems unlikely (and is also i assume not what you inferred since you replied with a link from before his presidency).

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