I built my own memory profiler (in Rust, on Linux)

Рет қаралды 59,484

Күн бұрын

To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/fasterthanlime
The first 200 of you will get 20% off Brilliant’s annual premium subscription.
This video was sponsored by Brilliant.
Follow me on Mastodon: hachyderm.io/@fasterthanlime
Support me on Patreon or GitHub: fasterthanli.me/donate
Source code for the memory visualizer: github.com/fasterthanlime/mevi
"The Linux Memory Manager" book (Lorenzo Stoakes): linuxmemory.org/
(Reference continue below)
Contents
00:00 Intro
01:09 Memory fragmentation explained with cars
02:26 Virtual memory 101
06:10 Observing simple programs with mevi
10:30 Sponsored segment (real)
11:33 Why does this Rust program leak memory, visualized
13:30 mevi is Rust on the front & back
15:40 userfaultfd: the reason why mevi works (slowly)
18:13 The hard bits
21:06 Some bigger programs seen through mevi
22:15 Y'all are so good to me
More references
The Quest for Netflix on Asahi Linux (David Buchanan): www.da.vidbuchanan.co.uk/blog...
Making our own executable packer: fasterthanli.me/series/making...
Swiss Tables Design Notes (Abseil): abseil.io/about/design/swisst...
SwissTable CppCon talk (Matt Kulukundis): • CppCon 2017: Matt Kulu...
Live migration: en.wikipedia.org/wiki/Live_mi...
Chromium’s Zygote process: chromium.googlesource.com/chr...
bytehound memory profiler: github.com/koute/bytehound

Пікірлер: 115

@fasterthanlime Жыл бұрын

To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/fasterthanlime The first 200 of you will get 20% off Brilliant’s annual premium subscription.

@mzg147 Жыл бұрын

Yes!! Go get that sponsors boyy

@PaulFisher Жыл бұрын

Stack that paper baby

@aleksandermirowsky7988 Жыл бұрын

Honestly, every one of your videos always feel like a blessing. It's reminiscent of a sage descending from the mountains to share his sacred knowledge with the village folk.

@fasterthanlime Жыл бұрын

I see myself more like a fool tumbling down the hill every so often to bestow the curse of knowledge upon others, but I think the idea is roughly the same!

@charetjc Жыл бұрын

@@fasterthanlime You have an amazing ability to digest all you learned into a concise, interesting, and easy-to-follow manner. This video is excellent.

@JheregJAB Жыл бұрын

every one of your videos up until now has been right on the perfect edge of "I understand, but we're stretching it". I've got to be honest, this one managed to get over my head. That's not bad, its a challenge. Gonna have to rewatch it a couple times and do some extra research on top of it, I think.

@fasterthanlime Жыл бұрын

Thanks for the feedback! That video definitely warrants at least a couple follow-ups, I have unscripted ideas that I think could be neat. Gotta change it up a little, those videos are an enormous amount of work.

@abiiranathan Жыл бұрын

PHD-esque stuff. Mind-blowing 🤯

@dnullify100 Жыл бұрын

Your content is the absolute nexus of production quality, content quality, and approachability. The thoughtful and smooth crescendo of complexity that keeps one engaged for the whole video/story.

@multispectrum Жыл бұрын

This was absolutely fantastic. A follow up video or resources to explain things in more detail for people who don't have much low level experience would also be great.

@fasterthanlime Жыл бұрын

I have a couple in mind, but can you give me a few areas in particular you'd like cleared up?

@multispectrum Жыл бұрын

@@fasterthanlime Again, fantastic work, you're a really great teacher. Watching it again, I wrote down things that I have questions on. There are definitely resources on most of things available and I have a good place to start learning from now. The largest gap in available resources to me seems like eBPF. What defines the memory sections (ro, rw, re)? (Making our own executable packer is on my list to read yet.) TLB makes sense for virtual->physical, but what does walking the page table mean? (Also how does the TLB cache recent memory accesses? Is there a large performance hit to TLB misses? And can the TLB only work for a single process at a time? How does flushing work?) What exactly is a page fault? What is stack/heap, and how to they relate to syscalls (break, mmap, madvise, etc)? Does madvise just allow the kernel to remove pages from the resident memory, but they're still in the virtual memory? What is malloc, malloc_trim, calloc, realloc, free, and how do they relate to syscalls, heap, virtual address space, etc? With your mention of eBPF I lost all understanding of what eBPF is. I thought that it was only for packet manipulation and statistics collection on network traffic. A video on eBPF would be awesome. Everything after ~18:00 I was completely lost. That could probably take a decade of learning. (ptrace, userfaultfd, what is a fd?, what's a setuid binary, self-tracing processes, PID namespaces, seccompbpf?)

@sambazeley5366 Ай бұрын

I watched this video all the way through assuming that this was another big programming channel. I was surprised to see how small your channel is. There is so much quality!

@FryuniGamer Жыл бұрын

"My previous video about this was, in fact, correct. I was as shocked as you are" I wish I had that confidence, but even more I wish I was at the level of saying such a thing.

@walksanator 2 ай бұрын

Thats not co fidence though...

@SamSargent-kh7gl Жыл бұрын

It's such a relief that people like you make content for us like this. This is exceptional, cheers.

@louisfifteen Жыл бұрын

"This town aint big enough for both of us" by "The Sparks" The one playing the piano is what this guy reminds me off. They were brilliant and so is he.

@ahuggingsam Жыл бұрын

as always I'm gonna have to go over some of this stuff multiple times, but I'm learning so much. Thanks for making these videos Amos, I doubt I could clearn about this stuff without someone like you making it engaging.

@artifishul Жыл бұрын

Love this content. Thanks for all the work you put in to explain this so well

@meegleeto Жыл бұрын

I can't believe the "this video is sponsored by" bit actually paid off

@fasterthanlime Жыл бұрын

It was all just practice 🧐

@kehaarable Жыл бұрын

Your videos are great. I was looking for some rust videos when I stumbled upon them. I've been programming for about 20 years so most videos are painfully slow. Your videos always touch on subjects that I've never had to deal with. I've not learnt a huge amount of rust, but my understanding of how systems actually work has grown a lot, and enticed me to think more about the tools I take for granted every day and to think about in earnest how I would build them. So thank you!

@lejee_ Жыл бұрын

great video, as always :) btw. nice seeing you have a (real) sponsor now!

@nindalf Жыл бұрын

Fantastic video, thank you for making it. I'd love to see a video of using mevi to optimise existing programs.

@Dygear Жыл бұрын

Crushed it again Amos! So many things to try this out on!

@nikandfor Жыл бұрын

Super cool! I love the observability, and this is the next level!

@desuburinga Жыл бұрын

Amazing video, like everyone else mentioned, absolutely mind blowing stuff! Keep up the great work and congrats on the sponsorship!

@zperk13 Жыл бұрын

Congrats on getting sponsored!

@flippert0 6 ай бұрын

While way over my head for now, this feels amazing! One day, I might be able to understand what's going under the hood.

@appelnonsurtaxe Жыл бұрын

That was both interesting and very enjoyable to watch! Thanks a lot for making these videos.

@driedurchin Жыл бұрын

This video exposes a lot of "false dogma" IMO. You traditionally hear the simple explanation of the cost of dynamic vectors, usually saying something like "if a push exhausts the capacity, you have to reallocate and copy everything over", which is *morally* true, and maybe was *actually* true 20 years ago. Nowadays, on modern OSes its interesting to see how it's not the case. Yet another reason to never preemptively optimize. Measure first!

@employee9911 Жыл бұрын

Really enjoy content like this

@kickeddroid Жыл бұрын

What's crazy is I looked this up earlier this morning, taking a break now and watching youtube I see this lmao

@OhadLutzky Жыл бұрын

Excellent job, and congrats on the sponsor!

@patryk6769 Жыл бұрын

Thank you Brilliant for sponsoring this video ❤

@jorgeosorio1613 10 ай бұрын

this video was great, I loved the introduction.

@Onkoe Жыл бұрын

I love these videos! I’d happily watch a one or two hour version. I have ADHD, so your articles are a lot harder for me, but these videos are perfect!!!

@asadullahfarooqi254 Жыл бұрын

yo brah it was amazing, can't wait to see the eBPF :)

@fluffy_tail4365 Жыл бұрын

Incredible video as usual

@MrMariy0 Жыл бұрын

very interesting, as always!

@craigcraig6248 Жыл бұрын

Wow, great video. Im glad i found this channel.

@chylex Жыл бұрын

I love the visualization of memory allocations

@bakabaaka2681 Жыл бұрын

Damn... Great video man.

@clo4 Жыл бұрын

Yooo get that bag! Good job Amos!!

@zperk13 Жыл бұрын

Thanks for captions!

@fasterthanlime Жыл бұрын

Thanks! I used Whisper for these but even then it's a solid 2.5x-the-runtime of manual cleanup/sync work :)

@gruelingpine1857 8 ай бұрын

this is pretty cool! Your profile pic reminds me of the scrap metal artist from the Iron Giant

@flyingsquirrel3271 Жыл бұрын

I'm so happy that you casually use the term "kibibytes" :D (I had this discussion a few times with unteachable people...)

@__mrmino__ Жыл бұрын

Technically sections in an ELF don't need padding. The section header contains the size field, the loader in the kernel can just load the non-zero stuff and leave the rest. Filling ELF section with zeroes ensures that the page is also filled with zeroes, instead of garbage. It has nothing to do with page alignment. The virtual *adresses* still need to be page aligned though, as most MMUs don't support setting memory attributes on anything other than a whole page.

@jackevansevo Жыл бұрын

Blown away by every single one of these videos

@johanngambolputty5351 Жыл бұрын

Not sure I understood any of that, but I was impressed ;)

@gpugpugpu 8 ай бұрын

Another fire fasterthanlime video let’s GOOOOOOOOO

@TobiasFrei Жыл бұрын

Oh, these great contributions of yours. You *do* have an impact on the way I think about- and write Rust. Looking forward to some eBPF. Will you go the Aya way? 🤓🐝

@TobiasFrei Жыл бұрын

Or no. It won't be the Aya way. Just as likely you're gonna roll it yourself 😋

@fasterthanlime Жыл бұрын

I've naturally looked at Aya since I've used it before for networking, but I'm unsure whether it'll do the job for that project. Time will tell!

@musikosv Жыл бұрын

Very interesting, thanks for sharing!"

@oyewodayo Жыл бұрын

You're a good teacher. You explain things differently, even a 2 years old kid will understand anything you explain.

@simonfarre4907 Жыл бұрын

You haven't looked at RR code base before? A lot of this stuff's in there, although, your project I think is a better source to learn this stuff from since it's probably smaller in scope (and it's in Rust, RR is written in C++). But you've got the sending of fd's over a socket, the injection of syscalls, etc and all that really cool Linux stuff.

@fasterthanlime Жыл бұрын

I've never cracked rr open (but I've used it a couple times!) but I 100% trust you on that. mevi definitely makes for a smaller surface to study, and you can always drop into some of the crates it uses if you're interested in a specific abstraction!

@JustAnotherLight Жыл бұрын

At the beginning of the video, I thought Brilliant's starting a Rust course!

@ExCyberino Жыл бұрын

rm -rf = rename --recursive --flawlessly Basically solves the slash problem in all files

@Leik000 Жыл бұрын

Going from "sponsored by coffee" to "sponsored by Brilliant". KZfaq achievement unlocked.

@fasterthanlime Жыл бұрын

All that caffeine finally paid off!

@bowarc Жыл бұрын

Rly cool, keep up the content, it's really interesting l!

@DarrienGlasser Жыл бұрын

Buses and trains don’t exist in that universe I didn’t know you visited America recently :o

@pkoch Жыл бұрын

If only my OS class was this good. ❤

@Otakutaru Жыл бұрын

I didn't expect the linux kernel to be so fiddly. Is everything related to low level OS that challenging? For example, memory management on windows? Because I got scared

@fasterthanlime Жыл бұрын

I think the short answer is yes. But the good news is that it's "knowable", and then you slowly change from feeling intimidated by it to feeling irritated by it at times 🙃

@oyewodayo Жыл бұрын

Please do a series on Axum indepth.

@MateuszWykurzIsAwesome Жыл бұрын

Thanks!

@fasterthanlime Жыл бұрын

Thank you for your support !

@versacebroccoli7238 Жыл бұрын

It's so crazy that the minimum memory a program can allocate (4k) used to be sold as high end ram sticks. I was reading a comment on some other tech video and a person said their computer could have up to 20 4k ram cards. But that would take all their expansion slots.

@fasterthanlime Жыл бұрын

It was another time, for sure! From devblogs.microsoft.com/oldnewthing/20200728-00/?p=104012 Huge pointers could refer to memory blocks larger than 64KB by adjusting the segment whenever the offset overflowed.¹ Pointer arithmetic with huge pointers was computationally expensive, so you didn’t use them much.²

@CramBL Жыл бұрын

Great video. What's the website you use for making those sketches at @3:11 for example?

@fasterthanlime Жыл бұрын

That's draw.io / diagrams.net!

@YTCrazytieguy Жыл бұрын

Yay sponsorship!

@Vampirat3 Жыл бұрын

@fasterthanlime , you get mad respect. great video thank you.

@EricTorreborre Жыл бұрын

Your videos are always mind-blowing, not only for their content but also for the quality of the presentation. Kudos!

@user-ed5qx1ih3i Жыл бұрын

Your doctor is great!

@bxnny0374 Жыл бұрын

Have nothing to say, just commenting to help this video out so more people can see it :) insanely high quality

@heyiamigor Жыл бұрын

Could you please share your code editor setup? I saw you using VSCode and vim extension, what other configs/extensions do you use? Thx!

@brazni Жыл бұрын

17:29 Don't tell me what to do magic mind reading slides!

@focusEngineered Жыл бұрын

AMAZING

@Verrisin Жыл бұрын

so, do we see if Firefox is leaking memory in the "third way" ? That would be a cool thing to find out after the effort.

@fulgorete Жыл бұрын

This is not a trivial subject. Good work overall

@kowalkem Жыл бұрын

Missed opportunity here - should have been built on Gentoo or at least Arch 😉 In all seriousness - massive thumbs up 👍

@fasterthanlime Жыл бұрын

Oh I've served my time in both the Gentoo & ArchLinux jails, I'm free now, I can use Ubuntu and still have street cred 😎

@sammay1540 Жыл бұрын

Gold

@thepetesmith Жыл бұрын

I’d like to see faster than lime’s car.

@Verrisin Жыл бұрын

damn, ok, growing a Vec looks a LOT nicer than something like ArrayList in JVM, which I think DOES copy the array. - I might be wrong and it does some magic behind the scenes, but this looks beautiful ...

@as-qh1qq Жыл бұрын

This is way above my pay grade.

@kasvith Жыл бұрын

Can you do Zig vids as well

@m4rt_ Жыл бұрын

could you make a thing like RemedyBG... but for linux?

@mint_fresch4329 7 ай бұрын

imagin u#r talking about linux kernel very basic/complex stuff and get an normal sponsor xD, bro u made it xD

@jeffg4686 Жыл бұрын

nice

@Verrisin Жыл бұрын

I wonder if this needed so much unsafe code, it would have been easier to write in Zig ? Probably not, but I wonder. (and yes, it would probably not share code with browser) - Also, I have zero clue how one would even research all the documentation to make all this crazy stuff work ... - How to even figure out all the magic kernel stuff? And how to do it from something other than C ? EDIT: 22:22 - I see. So that's how! Naruhodo.

@fasterthanlime Жыл бұрын

I've seen that same "we switched from unsafe Rust to Zig" article that you have, but in that case, no, Rust was plenty comfortable, thanks to a wealth of crates that exposed all the system interfaces I wanted :)

@Verrisin Жыл бұрын

@@fasterthanlime hehe, yup. - Awesome to know! - It's good to know it can be abstracted away into a safe crate.

@Dragon-xd4ru Жыл бұрын

Keep making more videos pls 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏

@gakman Жыл бұрын

lol "Stop reading these slides and pay attention"

@rotteegher39 Жыл бұрын

Everytime you say "Mevy" I hear "Bevy" instead (rust game engine)

@sudiproy4413 9 ай бұрын

😨 18:13

@justaguy1299 Жыл бұрын

This made me think about a video about the same topic I saw a while ago, there they made a tool that compacts the fragmented memory pages of a process. Might be an interesting watch kzfaq.info/get/bejne/mZeFda2Ty7iReGQ.html

@fasterthanlime Жыл бұрын

Yes! I've been meaning to talk about MESH - anything Emery Berger is involved in is sure to be fascinating :)

@muneebdev Жыл бұрын

"a lesser man"

@xmeo209 5 ай бұрын

I have no idea what this man says, but its very uhm.. interesting?

@kaioh33 Жыл бұрын

Pagliaci joke😂😂😂

@motbus3 2 ай бұрын

For a month? Hummm...

@victorfds Жыл бұрын

I don't understand 7 in each 10 words you say.

@fasterthanlime Жыл бұрын

Is my pronunciation that bad?

@victorfds Жыл бұрын

@@fasterthanlime absolutely not. I have a little bit knowledge about low level programming. The topics looks so deep that I can't get it.

@fasterthanlime Жыл бұрын

I have quite a few videos about that but I've been slowly figuring out how to do more accessible videos with a tighter scope. I'll get it right someday!