[HN Gopher] /* You Are Not Expected to Understand This */
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/* You Are Not Expected to Understand This */
Author : todsacerdoti
Score : 46 points
Date : 2020-10-21 12:12 UTC (10 hours ago)
(HTM) web link (community.cadence.com)
(TXT) w3m dump (community.cadence.com)
| brundolf wrote:
| > Linux is 15+M lines of code....But at only 9,000 lines, Unix v6
| was tractable, people continued to study it (and maybe still do),
| and the famous comment lived on.
|
| > Reading real programs is a part of learning computer science
| that should be emphasized more. As an undergraduate, we mostly
| programmed in BCPL, a local Cambridge language that is the fore-
| runner of C and C++. We had access to the full source code of the
| compiler and reading it was as valuable as the more theoretical
| aspects we learned in our compiler-writing course. Today, with
| open source, it is easy to read the source code for many systems
| actually in use (Linux, the Apache web server, Hadoop,
| TensorFlow, and thousands more) but these are hundreds of
| thousands, if not millions, of lines of code. As I said above,
| Linux is somewhere between 15M and 20M lines of code, depending
| on just what you include.
|
| This is an interesting problem. Modern software is so huge and
| complicated that it's not feasible to go read it just as a
| learning exercise. Linux devs can probably spend years
| contributing to the project without having even visited all of
| its dark corners, much less understanding them.
|
| Not sure what can be done. Though I am tempted to go see what a
| 9,000 line OS looks like.
| throwaways885 wrote:
| > > [...] at only 9,000 lines, Unix v6 was tractable, people
| continued to study it (and maybe still do), and the famous
| comment lived on.
|
| Wow, Unix is a work of art. I have hobby projects at 2x SLoC
| which are literally just small web services :(
| qsort wrote:
| >Modern software is so huge and complicated (...) Not sure what
| can be done.
|
| Nothing. Any sufficiently complex system or body of knowledge
| is too large for any one person to understand. Does any
| physicist know ALL physics that was ever done? Does any one
| engineer know how to build a Ferrari? Let's be honest, we take
| for granted _a lot_ of stuff that we don 't fully understand,
| Linux is a major piece of infrastructure, it's natural nobody
| can fully wrap their head around it.
|
| > Reading real programs is a part of learning computer science
| that should be emphasized more.
|
| I had never thought of this in an educational sense, but I
| definitely agree. I sure wish I was taught more of that, toy
| problems get boring quickly.
| person_of_color wrote:
| There is so much driver and feature spam in the Linux codebase.
| I really wish a beautiful, minimal microkernel approach would
| have won out.
|
| Why can't distros be a package of microkernel + drivers?
| galangalalgol wrote:
| Because a monolith is easier to get working on a quick
| timeline and it will generally outperform code that makes
| compromises for the sake of its' developers sanity. At least
| as long as you can keep the insane developers from eating
| each others eyes.
| qayxc wrote:
| > Why can't distros be a package of microkernel + drivers?
|
| Performance. Basically, the required amount of context
| switches (since all drivers run in user mode) impacts
| performance and cache use in a negative way compared to
| monolithic kernels. Whether this is still a significant issue
| with modern designs, I don't know, but that was the argument
| back in day (i.e. the early 90s when Linux came about).
| someguydave wrote:
| because nobody is willing to pay alot extra for software of
| high quality
| gnulinux wrote:
| Why does it matter? If you want to read scheduling code of
| linux, no one forces you to read 5M+ lines of driver code. If
| linux was just a microkernel, and distros shipped drivers,
| you'd still have to read roughly the same number of lines to
| understand linux scheduling. If you want to read the entire
| linux code, you can still do it, just ignore the driver code
| if you're not interested in them; otherwise in your scenario
| you'd be reading driver code in distros as well.
| dang wrote:
| If curious see also
|
| related from 2008 https://news.ycombinator.com/item?id=203437
|
| dmr's comments are at
| https://web.archive.org/web/19990501224738/http://cm.bell-la...,
| followed by _Comments I do feel guilty about_.
| daly wrote:
| I have my photocopied version... but I also bought the book.
| sam_bristow wrote:
| I'm sure I read somewhere that the original comment was intended
| more along the lines of "this bit isn't going to be on the exam"
| rather than "this bit is to complex for your feeble brain".
| JoeAltmaier wrote:
| But there are absolutely hard places in some code, that mere
| mortals should change at their peril. Most complex code has
| some place where it all meets, 6 or 7 constraints and issues in
| a few lines. Most people aren't in a place to (want to)
| understand all the issues, and its reasonable and fair to say
| "Here there be dragons".
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