@ljs@social.kernel.org
@ljs@social.kernel.org avatar

ljs

@ljs@social.kernel.org

Linux kernel mm contributor, kernel/systems developer, writing a book about mm.

C/C++/(rust at some point!)

Book - https://linuxmemory.org/
Me - https://ljs.io/
Music - https://soundcloud.com/distal_music/

Arsenal fan, cat maniac, synth experimentalist. Brit.

Opinions are all my own and represent nobody else.

This profile is from a federated server and may be incomplete. Browse more on the original instance.

ljs, to random
@ljs@social.kernel.org avatar

When people tell you self driving cars are safe in 99% of situations, remember that I can sell you a carbon monoxide detector that works in 99% of real-world situations consisting of a piece of paper saying 'you're fine bro'

Di4na, to random
@Di4na@hachyderm.io avatar

For everyone that calls for ways to make open source more secure, or for all their magical solutions that will provide money and resources to FOSS maintainers, please read this.

This is a rare account of the reality of maintainers, things that are hard, but also how much knowledge and niche expertise you need for anything in there.

That is why just giving money to experts will not help that much. It is too hard to train experts in this. But we may make it easier

http://rhaas.blogspot.com/2024/05/hacking-on-postgresql-is-really-hard.html

ljs,
@ljs@social.kernel.org avatar

@Di4na A very thoughtful piece, another factor I think that is often downplayed is the role of talent - the author of this piece is clearly very talented, but the number of people with enough talent in the world to work on highly complicated software like this is limited, so that adds YET ANOTHER filter on the number of people who can end up working on these things.

I think society as a whole tends to like to act as if anybody if they only want it hard enough could do these things whereas the reality is only a small fraction could.

ljs, to random
@ljs@social.kernel.org avatar

Another case where detailed commit messages really really help.

It blows my mind that any project decides not to provide detailed commit messages when the benefits are so massive...!
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1899ad18c6072d689896badafb81267b0a1092a4

ljs,
@ljs@social.kernel.org avatar

@6d03 @liskin commits are smaller granularity than PRs and different scope, that doesn't work at all.

It's just laziness it's quite simple

ljs,
@ljs@social.kernel.org avatar

@6d03 @liskin trying to be more zen in 2024:

I respectfully disagree with this practice :)

ljs,
@ljs@social.kernel.org avatar

@6d03 @liskin yeah this is the 'argument', maybe I'll be less zen and tell you it's just terrible. It's not debatable, it's terrible.

Why are you even using source control?

You end up with a 10,000 line commit? No bisect now, no ability to back port, no description of the logic behind things, no separation of moving code/changing it.

I've seen somebody do a 5,000 line move of code and subtle changes in it - good luck dealing with that as one commit.

You remove all code-specific context, all things that are sub-PR level.

All for what purpose? To make life a little easier or neater?

If people can't be bothered to rebase properly, then why on earth do you think they'd put every bit of detail needed in a PR description?

It's impossible to argue these things anyway, and pointless, because those making the decisions are not the ones dealing with the consequences of this.

I've literally run into every single one of these issues in practice.

And you're commenting on a post where I literally point out the benefit of a high-granularity comment that wouldn't exist in this scheme?

Come on man.

ljs,
@ljs@social.kernel.org avatar

@6d03 @liskin to be clear I"m not attacking you at all :) just have strong feelings on this issue. I'm just attacking the auto-squash concept as an idea.

ljs,
@ljs@social.kernel.org avatar

@janriemer @chriskrycho Spot on!

As I'm (nearly done) writing a book about mm to learn mm deeply, I totally buy the 'write about it to understand' thing, as I've experienced it first hand, endlessly.

ljs,
@ljs@social.kernel.org avatar

@6d03 @liskin you're a good man for making the effort!

While I (obviously) disagree with auto-squash taking the time to really be detailed in what place you possibly can already adds a ton of value.

I think the guidelines at https://www.kernel.org/doc/html/latest/process/submitting-patches.html are relevant even for other projects (in the 'describe your changes' bit). Obviously tailor accordingly.

ljs, to random
@ljs@social.kernel.org avatar

I find the 'death of the high street' people tiresome. They're almost as bad as 'this capitalist system which has lifted billions out of poverty and which I owe everything is utterly broken' people, but you know, not quite.

Both share a total misunderstanding of where wealth comes form. It doesn't grow on a tree waiting for a big daddy or mummy in the sky to hand out to people.

It is forged by enterprise. And enterprise lives and dies on demand, if the demand isn't there, then what? Are we supposed to fund businesses as a charity serving confused nostalgic people?

The high street in the UK is dying because it was and is largely shit, and something better came along.

Shops that offer something different/better than online will do well, those that try to sell overpriced tat in a shabby retail space making no effort are, thankfully dying.

Woolworths was a shit hole, BHS was a shit hole, sorry. And they died because people could find far better elsewhere.

It's this weird rose-tinted thing. I was born in the 80's and saw how it was pre-internet, and guys, what the fuck? 🤣

ljs, to random
@ljs@social.kernel.org avatar

This fosstodon thing reminds me that those who go on the most about how considerate they are about others (+ how everybody else is horrible) are so often the ones doing the most harm.

It's been a spot on tell for me for quite some time now... 'the lady doth protest too much methinks'.

The cure of course is humility, honesty and being willing to embarrass yourself by openly saying 'yeah ok I was wrong'.

Deeply powerful tools, very very rarely displayed, especially by those with even the smallest semblance of power...

ljs, to random
@ljs@social.kernel.org avatar

So @lkundrak often posts about doors, showing off Brno doors as if they are special, well now I have to show the end game of doors and yes it's British.

Sorry not sorry

ljs, to random
@ljs@social.kernel.org avatar

I made a bunch of kernel scripts to make life easier working with configuring/building/running a kernel in qemu etc.

They're a bit arch-specific and rough but in case anybody might find them useful :)

https://github.com/lorenzo-stoakes/kernel-scripts

ljs, to random
@ljs@social.kernel.org avatar

I know that people say wayland is the future and nobody cares about X yada yada, but it is pretty frustrating when wayland is broken for a whole bunch of things.

It's like a trend, similar to flatpak, the devs don't care so it doesn't get done but simultaneously you have to 'embrace' it even though it degrades your experience.

:'(

ljs, to random
@ljs@social.kernel.org avatar

Empathy to my Czech friends, horrible scenes in Prague. Hope everybody's ok.

ljs, to random
@ljs@social.kernel.org avatar

Honestly transistors are a scam, microchips consist of billions of tiny valves CHANGE MY MIND

ljs, to random
@ljs@social.kernel.org avatar

Rewatching alien covenant it really isn't that bad at all... yes some silly parts but the general thing still has great moments and lovely concepts

ljs, to random
@ljs@social.kernel.org avatar

While there are sometimes LWN articles/posts/etc. about things I cover in the book I generally try to avoid them as I've often found them to be counterproductive because:

a. I end up taking on assumptions the author did or speaking with 'their voice' rather than seeing for myself
b. The author might have made mistakes/glossed over things
c. The author is probably talking about a kernel version other than v6.0
d. The author often has a bias towards a certain problem/point of view that isn't 'exploring mm from bottom up'
e. I might miss things the code shows.

Therefore 99% of all I do comes from the source + me banging my head against the wall

ljs, to random
@ljs@social.kernel.org avatar

inb4 the phoronix article...

Linus having power cut merge window paused

https://lore.kernel.org/all/CAHk-=wjMWpmXtKeiN__vnNO4TcttZR-8dVvd_oBq+hjeSsWUwg@mail.gmail.com/

ljs, to random
@ljs@social.kernel.org avatar

Linus Clawvalds in a state of feline bliss

ljs, to random
@ljs@social.kernel.org avatar

@timnitGebru This is a direct result of Sam Altman and people like him lying about the capabilities of LLMs for financial gain.

The fact the bulk of tech + the media seem oblivious to this makes them just as culpable.

Expect many more harms like this. Yay. Just what the world needed, more sources of total post-truth bullshit...

RE: https://dair-community.social/users/timnitGebru/statuses/110930665056158940

DJDarren, to random
@DJDarren@mendeddrum.org avatar

Been reading a thread about Britain’s ‘obesity epidemic’, and it’s amazing how many thin people know how to fix it.

People clamber over themselves to wax lyrical about how we should encourage more exercise (we should), and how fast food joints should be held to account (they should), but the loudest voices never talk about it being a mental health issue.

I’m a fat fuck, I know I should exercise more and eat better. I did that for a year once and lost 30kg. Then I put it all back on again.

ljs,
@ljs@social.kernel.org avatar

@DJDarren as some of the replies to this thread indicate, people are so dead set on giving you a fucking lecture as if you don't know what to do they don't want to embrace the key point here which is that obesity is 100% a mental health issue.

And I speak from the position of somebody who has lost 15kg this year, I got the gym 6 days a week, I am super dedicated, yada yada.

That's not the point, the point is that I am addicted to shitty food, I love shitty food, I am like a recovering 'foodoholic' and can never be trusted around food generally ever, like ever. I have to maintain some kind of strict control forever or I'll pile it back on.

For me, I'm sure you can relate, the issue is food is one of the best drugs going, best ways of dealing with stress/anxiety/etc.

The only way I am making changes really is by having a totally bloody minded mentality at the gym and using the desire to gain muscle/lose fat to reveal the muscle to cope with giving up that drug/being strict.

Without that I'd just fuck it again, and maybe I still will I can't guarantee it. And hey I can look forward to bulking phases right? ;)

Thin people giving you long patronising lessons about caloric deficit while not grasping the mental health aspect is one of the most irritating aspects of this whole thing, fuck me haha.

drewdevault, to random
@drewdevault@fosstodon.org avatar

I do not understand why every modern Unix does not automatically generate a new swap encryption key on boot by default

ljs,
@ljs@social.kernel.org avatar

@drewdevault @levitte @ttmevans obligatory mention of the excellent https://chrisdown.name/2018/01/02/in-defence-of-swap.html article.

The purpose of swap is to balance memory pressure between the page cache and anonymous pages, so when memory pressure occurs the kernel has the ability to evict not-recently-used anon memory instead of just the page cache.

The page cache intentionally keeps a hold of file pages until reclaim so we can avoid disk I/O as much as possible, therefore naturally RAM usage grows over time.

Without swap the kernel has to ALWAYS evict page cache pages meaning that you might end up having to do a bunch of disk I/O that you might not otherwise have to have done.

TL;DR: Swap lets the kernel use memory for what is most in-demand, whether that is anonymous memory or cached file memory. Turning it off means that stale anonymous memory is ALWAYS preferred over cached file memory even if that doesn't make sense.

EDIT: Didn't realise Chris was on fedi - @cdown - incredible article, love it!

ljs, to random
@ljs@social.kernel.org avatar

My lad @kernellogger is a good lad.

ljs,
@ljs@social.kernel.org avatar

@vbabka @kernellogger ;)

It's enough to see you stick up for kernel devs Thorsten when people engage in the usual attacks (people learned nothing from the XZ thing), we can disagree on things like CVEs but you show spine where it counts :>)

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