alt.hn

7/3/2026 at 7:08:31 PM

FreeBSD ate my RAM

 https://crocidb.com/post/freebsd-ate-my-ram/

by theanonymousone

7/4/2026 at 9:29:49 AM

As for the “unauthorized” sign:

Book publishers used to print India/SEA-only editions of books only sold in those countries, significantly cheaper than in the US or Europe. Then a Thai guy realized that this would be a good business opportunity: buy cheaper books and then import them to the US. Wiley brought him to court, went to the SCOTUS, Wiley lost the case. So they ended up printing cheaper edition books.

https://en.wikipedia.org/wiki/Kirtsaeng_v._John_Wiley_%26_So....

Mind you "price discrimination" like this still exist in the digital world where locality is easier to be enforced. For example Steam has extensive regional pricing across countries so the same game can be significantly cheaper in Russia, India, Brazil etc. compared to US or EU

An example: https://steamdb.info/app/413150/

https://partner.steamgames.com/pricing/explorer

https://partner.steamgames.com/doc/store/pricing/currencies

by haunter

7/4/2026 at 11:10:39 AM 

    When Kirtsaeng moved to the US in 1997 to pursue an undergraduate degree in mathematics at
    Cornell University,[4] he discovered that textbooks (not just those published by Wiley, but
    of other publishers too) were considerably more expensive to buy in the United States than
    in his home country. Kirtsaeng asked his relatives from Thailand to buy such books at home
    and ship them to him to sell at a profit. He sold the imported books on eBay, making $1.2
    million in revenue, although the parties disputed the net profit amount.
A text book case (ha!) about one of the mechanisms that enable the free markets and trade to bring the prices of goods down.

by Joker_vD

7/4/2026 at 12:48:55 PM

Wow, I've only ever heard of regional pricing being described as an overwhelmingly positive concept. When phrased as "price discrimination", it invokes a completely different set of (negative) emotions in me.

It's weirdly uncomfortable knowing that phrasing has such a big impact on one's emotions. It really shows how vulnerable we are to manipulation.

by regenschutz

7/4/2026 at 4:29:37 PM

> It's weirdly uncomfortable knowing that phrasing has such a big impact on one's emotions. It really shows how vulnerable we are to manipulation.

My dad would discuss it in high school english courses: terrorist vs freedom fighter etc

by mewse-hn

7/4/2026 at 2:34:05 PM

That's why the current crop of authoritarian "think of the children" propaganda is so unreasonably effective

by vitally3643

7/4/2026 at 12:23:10 PM

Wow, how did we go from "it's impossible to enforce region locking online because you can transmit information instantly across the world" to "locality more easily enforced in the digital world"?

by stavros

7/4/2026 at 2:17:53 PM

Most people haven't started using vpns yet.

by exe34

7/4/2026 at 2:42:54 PM

You can't fool me with a VPN when your credit card is a US one.

by stavros

7/4/2026 at 5:29:15 PM

The wonderful world of “no ownership” means that if the store owner suspects anything is afoot they can pester you for evidence of residence and ban your account. Instead of saving 20% you risk losing 80% (don’t know the real price difference).

by close04

7/4/2026 at 2:34:55 PM

Silicon valley happened

by vitally3643

7/3/2026 at 9:48:31 PM

If you like this kind of post, you might like this “htop explained” post.

https://peteris.rocks/blog/htop/

by tiffanyh

7/3/2026 at 9:00:22 PM

Thank you for such a quality post.

by duendefm

7/3/2026 at 8:58:06 PM

the end struck me - a picture of an os book. I wonder if students these days retain their books after college, or do they get returned as a rental?

by m463

7/4/2026 at 12:30:11 PM

I graduated a decade ago but there was a pretty decent post-semester market for people selling their textbooks to other students (mostly via posting in various Facebook groups). Given the cost of college nowadays, if that ends up saving students a bit of money, it's probably worth it over saving the textbooks themselves.

Most years my parents ended up just driving my stuff to my aunt's house where she kept it in her garage over the summer after I packed it all up since I grew up several states away but my aunt loved in the area, and by the end of senior year, the textbooks I never managed to sell had added up to almost an entire extra bin (which was heavier than any of the others because they mostly just had clothes). For people who didn't have parents who loved driving everywhere in a large enough car or relatives in the area, this seems like it would be even more annoying (potentially ending up with just donating the leftover textbooks or maybe leaving them on the street like furniture and stuff often is at the end of the year on campuses). If people want to keep their textbooks, more power to them, but I'm not convinced that having a cheaper way that also simplifies the logistics of moving isn't better.

by saghm

7/3/2026 at 9:25:31 PM

I'm a professor at a community college in Silicon Valley, and my students use online textbooks. I try to use Creative Commons or other libre textbooks, but sometimes I use paid textbooks when they are heads-and-shoulders better than their libre alternatives. Some e-textbooks can be accessed on a subscription basis. I admit I prefer non-subscription materials, but a colleague advised me that often the book that students learn from is different from a good reference book that students can use once they've already learned the material. For example, my colleagues and I have had great success with an online, interactive textbook for discrete math. While the subscription is unfortunately only valid for the duration of the course, once students have learned discrete math, they could buy a used copy of Rosen's discrete math textbook as a reference.

The nice thing about e-textbooks is not needing to carry around a bunch of heavy books. I remember the tomes I had in my college days, such as Stewart's Calculus.

by linguae

7/4/2026 at 12:37:40 PM

> The nice thing about e-textbooks is not needing to carry around a bunch of heavy books. I remember the tomes I had in my college days, such as Stewart's Calculus.

I'm not sure how relatable this is for people outside of my age group (late millennial), but growing up we used to get chided about stuffing too much in our backpacks and shown presentations about how we were going to give ourselves scoliosis, but then had like two minutes between classes that might be on the other side of the building (meaning no time to stop at our lockers other than at lunch) and we'd get chided even worse if we didn't have our textbooks available for the days we happened to need them in class (which of course we were never told in advance, and some classes had multiple textbooks that wouldn't all get used every time).

I wish that we had iPads or Chromebooks or whatever back when I was in school not even because I would have wanted to have been able to surf the web or play games or whatever, but just to have a solution to having to pick between having a sore back or getting worse scolding (with a side course of hypocrisy either way).

by saghm

7/4/2026 at 7:31:17 PM

Which is why you leave your book inside the microwave the teacher might have in the back of the classroom.

People rarely actually use the microwave

by Melatonic

7/3/2026 at 10:21:32 PM

just hint students towards anna's archive and then sky's the limit

by NooneAtAll3

7/3/2026 at 9:31:35 PM

I bought as few textbooks as I could, but the few that I did buy are sitting in my parents' basement bookshelves somewhere.

by post-it

7/4/2026 at 3:22:31 PM

In college ATM and while I usually keep old textbooks, I have sold a couple on ebay to free up shelf space.

by kogasa240p

7/4/2026 at 6:13:08 AM

I wonder if these btop fixes got into the standard ports collection? Or even upstream?

I like the command for viewing the ARC cache size, never knew that. It's only 2GB on my system (of 64GB RAM).

by wolvoleo

7/4/2026 at 7:42:49 AM

>I like the command for viewing the ARC cache size

zfs-stats is also nice for more zfs internals like hit-rate L2 etc..

https://www.freshports.org/sysutils/zfs-stats

by BSDobelix

7/4/2026 at 12:22:07 PM

Thanks! I didn't know that one.

by wolvoleo

7/3/2026 at 10:35:40 PM

Great job on getting the fixes merged!

by efxhoy

7/3/2026 at 8:31:12 PM

Interesting post, it made me wonder. At one time FreeBSD swap usage/logic was far better than what Linux did. Is that still the case ?

by jmclnx

7/3/2026 at 10:21:59 PM

FreeBSD didn’t have memory overcommit and instead used strict swap reservation - each allocated anonymous memory page was supposed to have a corresponding swap page. This required 2x RAM swap space, otherwise you would get “out of swap” when forking a large process. FreeBSD implemented memory overcommit around 2000.

by man8alexd

7/3/2026 at 10:36:34 PM

Oh, so that's where that old nugget of wisdom came from! I've heard the rule about making your swap at least 2x your RAM for ages and thought it was just some old rule of thumb from the 80s. I didn't know there used to be a legitimate reason for it.

by jandrese

7/3/2026 at 9:54:43 PM

Yes, It's just not every tool is aware of ZFS ARC. Which is what this post is about. Author just describes in an odd way.

by 0x457

7/4/2026 at 1:51:58 PM

It's a bit odd that you have to query a filesystem-specific value to get simple memory usage stats.

by mike_hock

7/4/2026 at 5:00:32 PM

Despite having File System, ZFS is a lot more than just file system. Sooner you understand and make peace with it, easier it is to use it.

by 0x457

7/4/2026 at 4:20:51 PM

Which is exactly (part of) why people call ZFS a "rampant layering violation"!

by uniqueuid

7/3/2026 at 9:27:41 PM

I remember how NetBSD promoted itself as running on many more toasters than Linux once.

Then some NetBSD dev wrote on their mailing list that this is no longer true. Linux runs on more toasters now. (And also top 500 supercomputers, but toasters are the real metal to the petal test.)

These fights always remind me of:

https://www.jwz.org/doc/worse-is-better.html

It's an interesting piece of history too. I kind of evaluate it a bit differently, e. g. my summary is "momentum beats academic perfection". Which is not completely what it is about, but it is my own imperfect TL;DR summary.

by shevy-java

7/4/2026 at 12:14:21 PM

> but toasters are the real metal to the petal test.

Or is that a new tongue in cheek idiom?

AFAIK, it’s peDal, not peTal, and the other way around: pedal to the metal. The literal meaning is to push your accelerator pedal down to the floor of your car, which is made of metal.

by Someone

7/4/2026 at 4:33:39 PM

"metal to the petal" gives me more of a "gilding the lily" flavor, especially in cnotrast to the original construction.

Still not sure if it was on purpose, but I read it as a reference to a "but can it run DOOM?" benchmark.

by goodmythical

7/3/2026 at 9:46:55 PM

This basically fits my stereotype of BSD being a little bit more hardcore while Linux is a little more accessible… when the question was “can you install an OS on a toaster,” BSD had an advantage. Now that normal engineers have to make IOT toasters (for some reason) Linux should have the advantage, right?

by bee_rider

7/3/2026 at 9:49:23 PM

Normal engineers don't do that either.

by sublinear

7/3/2026 at 9:50:27 PM

why did that url point me to a scrotum in an egg cup

by Levitating

7/3/2026 at 10:07:26 PM

Seems like at a glance that website if it sees a referral from ycombinator, it redirects to that image.... In a private window it loads the 'intended' page.....

by UnlockedSecrets

7/4/2026 at 12:57:06 AM

HN has disappointed JWZ

by m0llusk

7/4/2026 at 12:40:07 PM

Just blackholing the request would be kinder than taking it out on the person following the link, given that their gripe seems to be more with the one who posted it (and that as a deterrent, it doesn't seem to be particularly effective given that it's been years since the first time I've seen this conversation play out in comments)

by saghm

7/3/2026 at 9:41:04 PM

[flagged]

by tom2ow

7/3/2026 at 9:23:24 PM

[flagged]

by tomeow

7/3/2026 at 8:54:13 PM

[flagged]

by naturalmovement

7/3/2026 at 10:40:56 PM

I've noticed that the various tools report different amounts of free memory. I appreciate finally having an explanation for why.

by craftkiller

7/3/2026 at 9:17:15 PM

Sure, but also some tools needed fixing.

by toast0

7/3/2026 at 9:25:43 PM

[flagged]

by shevy-java

7/3/2026 at 9:33:16 PM

The OS Crusades are over man

by edoceo

7/3/2026 at 11:34:36 PM

For real though, what is the point of running a bsd on a personal computer? Seems like intentionally handicapping yourself.

by irishcoffee

7/4/2026 at 7:40:42 AM

I have FreeBSD on all my personal machines and i feel the opposite of handicapped, however i use Linux (CachyOS) for gaming (as a VM with pass-thru).

by BSDobelix

7/4/2026 at 1:08:44 AM

Consistent ZFS tooling around the OS and ZFS support out of the box, which always works.

by soupbowl

7/4/2026 at 5:04:47 PM

So more so because of the storage drivers? I don’t have the specific concern, maybe that’s why I don’t understand the draw.

by irishcoffee

7/3/2026 at 10:33:29 PM

No ZFS no problem :)

by vermaden

7/4/2026 at 2:50:05 AM

Netcraft confirms it.

by acheron

7/4/2026 at 9:42:51 AM

~all Browsers on FreeBSD (Chromium/Firefox/Librewolf) have Linux as User-Agent.

by BSDobelix

7/3/2026 at 9:41:07 PM

[flagged]

by tom2ow

7/3/2026 at 9:15:37 PM

[flagged]

by hnloser

7/3/2026 at 10:53:24 PM

I don’t understand the part about using heuristics and deciding what counts as used memory…

Used memory for the system is always total minus available.

Heuristics? I would hope that the system knows precisely what is using every single byte of physical and virtual memory. Is this a reporting problem? Why do we have to settle for heuristics and not the exact number?

by drdexebtjl

7/3/2026 at 11:21:21 PM

> I would hope that the system knows precisely what is using every single byte of physical and virtual memory.

Of course the system knows what is using every page. The difficulty is really in how to account for pages that are backed by disk.

If you count all of those as free, that's not accurate. If you count all of those as used, that's not accurate either. Additionally, FreeBSD (at least) doesn't have separate queues for disk backed pages, so there's not really a good way to know how much of your active (or inactive) memory is disk backed.

As an additional caveat that measuring active/inactive has costs. In the past, FreeBSD wouldn't really do the work for that until it needed to... I know some stuff changed, but I don't remember where it ended up; it wasn't great when it bulk marked a ton of pages as inactive and then the active ones would fault back in.

by toast0

7/4/2026 at 1:18:47 AM

This is only really a problem if you accept overcommit as a force of nature that can't be changed or tweaked (you can still do address space reservation without needing overcommit)

If you don't, it becomes rather easy (and strict commit accounting is done for example on Linux even if it isn't used in some cases)

Memory mapped files can be entirely recreated from the disk so no need to charge for them. Anonymous pages (whether private or shareable) have to be charged. Shareable memory is the harder one to charge. (The case where a mapping is used by only one can get charged as private commit.) These two previous cases are charged even if in a swap file or whatnot

by jkrejcha

7/3/2026 at 11:49:47 PM

> If you count all of those as free, that’s not accurate.

Why not? It depends on what you’re measuring. Physical memory? They count as free. Virtual memory? They count as used.

The ambiguities only arise when we stop making that distinction very clear.

by drdexebtjl

7/4/2026 at 2:49:12 AM

> It depends on what you’re measuring.

What I want to know is do I have enough physical memory for what I'm running.

Sure, I can drop disk backed pages and recreate them as needed, but when it happens too often, there goes performance.

by toast0

7/4/2026 at 4:20:34 AM

Yep.

Thrashing is a well known known issue that can occur with swap, but it can also happen from page cache or memory mapped files. Indeed not having swap enabled can make things worse, as private pages that haven't been used in a hours cannot be swapped out to keep the important files cached or memory mapped.

Realistically for measuring physical memory sufficiency, you care about memory/data of any type (even files) that will be used in use upcoming time period, and ensuring that a sufficient percentage of it can be held in physical memory to avoid thrashing.

This is hard! Technically impossible to know for the general case (halting problem), and all methods of trying to approximate it involves trade-offs.

by jsmith45

7/3/2026 at 11:10:03 PM

The thing is it's easy to define free, unused memory. But a lot of the used memory is your system caching stuff that would be free if you needed more than what's actually free. So you can see you have 1g of free memory out of your 4g, but then you allocate 3g and it will do without a sweat and you'd be confused. So you have to go and dig for what those caches are and report that they're effectively free too.

by CrociDB

7/3/2026 at 11:39:24 PM

Instantly reclaimable disk caches should count as available, and they do.

This isn’t hard. The OS should just expose a counter for available memory instead of having applications understand every type of memory reservation.

edit:

Linux does this, but it has its own share of issues with memory counters. The “cached” memory includes tmpfs and ramfs for seemingly no reason.

by drdexebtjl

7/4/2026 at 12:42:35 AM

> The “cached” memory includes tmpfs and ramfs for seemingly no reason.

If you're curious why that is by the way, it's because that's actually how these are implemented (tmpfs/ramfs is just a mount to a filesystem where the files never get marked clean[1])

[1]: https://www.kernel.org/doc/Documentation/filesystems/ramfs-r...

by jkrejcha

7/4/2026 at 1:09:12 AM

That’s clever. Makes for terrible UX, though.

AFAIK the only way for you to figure out how much of your disks is actually cached involves enumerating all tmpfs and ramfs mounts, summing their sizes, and subtracting the sum from the cache size reported by the kernel.

by drdexebtjl

7/4/2026 at 11:02:22 AM

Well, what's the alternative? Invent a new type of memory reservations specifically to account for tmpfs/ramfs mounts? That'd violate your own stated desired goal of

> The OS should just expose a counter for available memory instead of having applications understand every type of memory reservation.

by Joker_vD

7/4/2026 at 12:50:26 PM

I don’t see how it contradicts my goal. I want memory counters that abstract away kernel behavior that the application has no business accounting for.

by drdexebtjl

7/4/2026 at 12:57:50 PM

The applications, frankly, have no business accounting any memory at all outside of what they use themselves via sbrk/mmap.

by Joker_vD

7/4/2026 at 3:15:40 PM

I think a memory pressure indicator is useful. For example, if you’re writing a garbage collector, you can choose to hold off from returning pages back to the kernel when the system is under low pressure, and do this more often under high pressure.

by drdexebtjl

7/4/2026 at 3:26:00 PM

That's very, very marginally useful. If your application recently ran GC when the system was under low pressure and freed a bunch of pages (and still holds to them), and then some other application suddenly acquires a lot of memory, your application won't free those pages until next GC happens. Which most likely won't until you've used up all those freed pages, and at that point a lot of swapping will already have had happen.

Explicitly set per-application upper bounds à la GOMEMLIMIT and Java's -Xmx, together with cgroup's enforcement, seem to be much more useful in practice.

Or there was a proposal for some sort of SIGLOWEM signal that would be sent to all processes in the system (with default disposition of "do nothing") that'd allow applications to release some of its non-vital memory holdings: also a much more timelier notification.

by Joker_vD

7/4/2026 at 7:22:13 AM

That metric would give you a number of bytes which can be used for pages not backed by files, but it won't give you actual memory usage statistics:

It won't count executable pages and memory-mapped file use as "used" memory, so your system might display gigabytes "free" when it's starving, executables getting paused when code pages are paged-in from disk.

It's just less useful than what's displayed now. "Everyone is doing it wrong" is usually a signal that you're missing something.

by killerstorm

7/4/2026 at 8:54:44 AM

Linux MemAvailable from /proc/meminfo is just an estimation calculated as an arbitrary percentage (50%) of free and potentially reclaimable memory.

You can't determine how much of the memory can actually be reclaimed under memory pressure until you try to reclaim it.

by man8alexd

7/4/2026 at 1:15:03 PM

> You can't determine how much of the memory can actually be reclaimed under memory pressure until you try to reclaim it.

Yes, and I’m arguing that we should be able to, by having the kernel keep track.

by drdexebtjl

7/3/2026 at 11:16:33 PM

You will be surprised by how inaccurate memory measurements are.

by man8alexd

7/4/2026 at 10:24:03 AM

Not after reading this article. :-)

by stephan-cr