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Former Tesla Firmware Engineer Discusses the System

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Re: Former Tesla Firmware Engineer Discusses the System

#161

Post by snowwrestler »

dswalter wrote: post #16
sz4kerto wrote: post #8

Why is this interesting or surprising? Of course almost all challengers have hacky tech under the hood because they don't have the resources. Winning from that position is possible not because of generally better tech but by delivering something that the incumbents don't. Remember the demo of the first iPhone (vs the huge expertise of Nokia). Or how Microsoft won the desktop starting from a single user, cooperative m…

Cars weigh thousands of pounds and routinely drive upwards of 60 miles per hour. The success of the first iPhone or Facebook app didn't depend on using it to navigate through life-and-death situations not only for the users but also for everyone around them. There are places for 'move fast and break things'. But cars move fast already, and they can really break things.

The iPhone has to reliably connect for emergency calls and provide accurate location. That can be life or death. In fact, "Apple isn't ready to engineer phones at a life-or-death standard" was a fairly common critique of the iPhone in the early days. In response, Apple ran a little PR campaign around their radio engineering efforts--they had a web page that showed all the cool-looking rooms for testing radios, which they invited a couple reporters to tour, etc.

Re: Former Tesla Firmware Engineer Discusses the System

#162

Post by kevin_thibedeau »

gapo wrote: post #134
crististm wrote: post #109

Earlier quoted context omitted.

Technically there used to be (still is?) such a thing as realtime Linux but not _for_ Linux (which you probably meant the userland?). Regardless. There are many and far better alternatives to Linux for real time applications.

RT Preempt / Preempt-RT patch still exists. It slowly is being integrated into mainline as per everyone's wishes but it is still a thing.

The original RTLinux it also still usable and it provides it's own hard RT scheduler.

Re: Former Tesla Firmware Engineer Discusses the System

#163

Post by misiti3780 »

ddevault wrote: post #11

I used to work at SpaceX on the team that did a piece of software called "WarpDrive". It was a massive monolithic ASP.NET application, with large swaths done with ASP.NET WebForms and a slow frontier of ASP.NET MVC gradually growing when I was working there. This application was responsible for practically everything that ran the factory: inventory, supply chain management, cost analysis, etc. Elon is a big Windows f…

>Elon is a big Windows fan and pushed hard to run the whole shop on Microsoft tech

wow - this is surprising to me and wasnt mentioned in the biography - any ideas why ?

Re: Former Tesla Firmware Engineer Discusses the System

#164

Post by [deleted] »

JumpCrisscross wrote: post #137
8_hours_ago wrote: post #52

Earlier quoted context omitted.

> the rockets fly with a heavily customized Linux install My jaw hit the floor the first time I heard this. Why Linux instead of an RTOS?? Apparently Tesla's autopilot also runs Linux, which seems like a huge accident waiting to happen (pun intended).

> Why Linux instead of an RTOS? Same reason SpaceX eschews radiation-hardened processors for redundant off-the-shelf cores: supplier competition. There aren't many RTOS engineers on the market; there are many Linux engineers. Once they got over the cost of hardening the kernel, SpaceX found itself at a scaling advantage versus RTOS-based competitors.

[deleted]

Re: Former Tesla Firmware Engineer Discusses the System

#165

Post by brbrodude »

coldtea wrote: post #146
mlaretallack wrote: post #99

Earlier quoted context omitted.

Agree completely. Hard real time is possible with Linux, we use it for sub millisecond control of Traffic Lights. The only issue we ever hit is proving that the code running is the stuff we expected to run.

> we use it for sub millisecond control of Traffic Lights Why would anyone need "sub millisecond control of Traffic Lights"? Traffic lights are mission critical systems, of course, but even millisecond precision should be more than enough, and possibly even 0.5x-1 second precision...

if it controls a ton of them, then small stuff could get them to be intolerably out of sync maybe? I'm just guessing :p

Re: Former Tesla Firmware Engineer Discusses the System

#166

Post by jtwaleson »

shittyadmin wrote: post #145
JumpCrisscross wrote: post #137

Earlier quoted context omitted.

> Why Linux instead of an RTOS? Same reason SpaceX eschews radiation-hardened processors for redundant off-the-shelf cores: supplier competition. There aren't many RTOS engineers on the market; there are many Linux engineers. Once they got over the cost of hardening the kernel, SpaceX found itself at a scaling advantage versus RTOS-based competitors.

Not just that but holy shit some of those commercial RTOSes have major issues. I work in aerospace and we recently used one where the whole system would crash after ~230 days of uptime. At least with Linux you're getting a system that's been used so much that all major issues like that are ironed out. Nothing beats a few million testers.

248 days of uptime by any chance?

edit: I saw the same on a fleet of thousands of JVMs which hung on 100% CPU after 248 days very consistently. Closest thing to an explanation I ever got was perhaps it is storing uptime in hundredths of a second (why not ms???) in signed 32 bit integers, see: https://ma.ttias.be/248-days/ In the end we solved it by restarting with a cronjob between 2am and 4am after 247 days...

Re: Former Tesla Firmware Engineer Discusses the System

#168

Post by misiti3780 »

sz4kerto wrote: post #8

Why is this interesting or surprising? Of course almost all challengers have hacky tech under the hood because they don't have the resources. Winning from that position is possible not because of generally better tech but by delivering something that the incumbents don't. Remember the demo of the first iPhone (vs the huge expertise of Nokia). Or how Microsoft won the desktop starting from a single user, cooperative m…

what about the iphone demo was hacky ?- just curious

Re: Former Tesla Firmware Engineer Discusses the System

#169

Post by jackhack »

arcticfox wrote: post #120
mlaretallack wrote: post #99

Earlier quoted context omitted.

Agree completely. Hard real time is possible with Linux, we use it for sub millisecond control of Traffic Lights. The only issue we ever hit is proving that the code running is the stuff we expected to run.

> Agree completely. Hard real time is possible with Linux, we use it for sub millisecond control of Traffic Lights. Out of curiosity, why do traffic light controls need to be that precise?

resume-driven development?

Re: Former Tesla Firmware Engineer Discusses the System

#170

Post by kevin_thibedeau »

tntn wrote: post #96
compostable wrote: post #35

Earlier quoted context omitted.

Did you ever have to stand outside in the winter, in ice and show, with the hood propped open, spraying starting fluid into the carburetor, and manually holding the throttle open, so that your engine could get to the proper temperature? Did you ever floor a car and have the engine shut off because there was too much fuel? No thanks, I don't want to go back to those days!

I mean, 'JohnJamesRambo did say sometimes .

Like those times you just say "FTW, I'm gonna spew as much unburned fuel out the tailpipe as possible".
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