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Search - "allocator"
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So here I am sitting on my dusty laptop gaming laptop (because supposedly it would offer me better performance in compiling code and working with CUDA according to the people above me) at a research institute where I just started working at. I am told that there are some issues with the code and that it fails to build on Windows with MSVC that ships with Visual Studio 2017 and later.
I poor some hot tea from my insulated bottle I brought from home and start reading.
I look in this header file and what do I see - a custom uint24_t struct. Interesting...
I keep sifting through the code base. I find some functions that check and change Endianess. Ok, but the software is developed, built on and runs only on Win7 and later desktop systems. Never mind...
Further I find a custom "allocator" that is used throughout the whole code base. It has three inline static class member functions: allocate, copy and deallocate plus some private constructors. And these just wrap around the standard new and free calls. Some flavours of this class actually only deallocate (with a comment above them: "This allocator does not allocate. HANDLE WITH CARE!!!", which is btw the only "code documentation" I have managed to find).
But wait! What is this? A custom thread and mutex. Oh, and string, and vector.
Further down the rabbit hole I find a custom math library with a matrix class that does not support multiplication between a matrix and a vector. Perhaps not a use case I guess...
I continue and come across some UI-related calls. Interesting, I wonder what they are using as a framework. Oh, my...We have an extensive GUI custom framework written from scratch (drawing buttons and all).
All of this is to load an OBJ file and render it on the screen on a standard Windows PC in some way.
Very nice... ;_;1 -
I know I'm writing the correct integration tests when each one I add uncovers a new bug.
Still, it would be nice if just one of them passed first time.1 -
Assignment release: this is a basic assignment that is supposed to help you understand the basics of memory allocation. You are free to use any design you want, however you can implement more advanced features that would lean towards specific designs. What will be punished is that you don't have a dynamic memory allocator. We will run the tests for these offline after the deadline
2 days before the deadline: we released the tests for checking whether you're allocating memory dynamically, but these tests also check for this specific design. So fuck you for choosing any other design than this one. Have fun on sleepless nights.
Fuck me, I guess, for worthlessly working on a different design than they wished for, but didn't specifically ask for from the beginning. I just wasted 2 weeks of my life and feel unmotivated af to do anything anymore regarding this. Fuck this shit. Fuck them. Fuck this course.1 -
A full 4 level page table on x86_64 is over around 687 GB in size. Allocating it fixed size obviously won't work...
So now when allocating virtual memory pages for an address space I sooner or later have to allocate one page to hold a new page table... which has to be referenced by the global page table for me to use... where there isn't any more space... which is exactly the reason we allocated a new page in the first place... so I'm fucked basically8 -
This shit is fascinating, especially reading about the variations in function of the various brodmann areas:
https://en.wikipedia.org/wiki/...
My favorite schizo-interpretation of this is "your head is full of bees."
i.e. brodmann area 10, which is thought to be responsible for memory recall strategies (basically an adaptive memory allocator and heap) has about 250 million neurons in a pinprick of a volume.
A bee has about 1 million neurons.
In otherwords: the part of your brain that decides how memory is managed has only the equivalent brainpower of 250 bees, lol.
Obviously a simplification-to-the-level-of-absurdity but it's fun to intentionally interpret something to the level of distortion.11 -
YGGG IM SO CLOSE I CAN ALMOST TASTE IT.
Register allocation pretty much done: you can still juggle registers manually if you want, but you don't have to -- declaring a variable and using it as operand instead of a register is implicitly telling the compiler to handle it for you.
Whats more, spilling to stack is done automatically, keeping track of whether a value is or isnt required so its only done when absolutely necessary. And variables are handled differently depending on wheter they are input, output, or both, so we can eliminate making redundant copies in some cases.
Its a thing of beauty, defenestrating the difficult aspects of assembly, while still writting pure assembly... well, for the most part. There's some C-like sugar that's just too convenient for me not to include.
(x,y)=*F arg0,argN. This piece of shit is the distillation of my very profound meditations on fuckerous thoughtlessness, so let me break it down:
- (x,y)=; fuck you in the ass I can return as many values as I want. You dont need the parens if theres only a single return.
- *F args; some may have thought I was dereferencing a pointer but Im calling F and passing it arguments; the asterisk indicates I want to jump to a symbol rather than read its address or the value stored at it.
To the virtual machine, this is three instructions:
- bind x,y; overwrite these values with Fs output.
- pass arg0,argN; setup the damn parameters.
- call F; you know this one, so perform the deed.
Everything else is generated; these are macro-instructions with some logic attached to them, and theres a step in the compilation dedicated to walking the stupid program for the seventh fucking time that handles the expansion and optimization.
So whats left? Ah shit, classes. Disinfect and open wide mother fucker we're doing OOP without a condom.
Now, obviously, we have to sanitize a lot of what OOP stands for. In general, you can consider every textbook shit, so much so that wiping your ass with their pages would defeat the point of wiping your ass.
Lets say, for simplicity, that every program is a data transform (see: computation) broken down into a multitude of classes that represent the layout and quantity of memory required at different steps, plus the operations performed on said memory.
That is most if not all of the paradigm's merit right there. Everything else that I thought to have found use for was in the end nothing but deranged ways of deriving one thing from another. Telling you I want the size of this worth of space is such an act, and is indeed useful; telling you I want to utilize this as base for that when this itself cannot be directly used is theoretically a poorly worded and overly verbose bitch slap.
Plainly, fucktoys and abstract classes are a mistake, autocorrect these fucking misspelled testicle sax.
None of the remaining deeper lore, or rather sleazy fanfiction, that forms the larger cannon of object oriented as taught by my colleagues makes sufficient sense at this level for me to even consider dumping a steaming fat shit down it's execrable throat, and so I will spare you bearing witness to the inevitable forced coprophagia.
This is what we're left with: structures and procedures. Easy as gobblin pie.
Any F taking pointer-to-struc as it's first argument that is declared within the same namespace can be fetched by an instance of the structure in question. The sugar: x ->* F arg0,argN
Where ->* stands for failed abortion. No, the arrow by itself means fetch me a symbol; the asterisk wants to jump there. So fetch and do. We make it work for all symbols just to be dicks about it.
Anyway, invoking anything like this passes the caller to the callee. If you use the name of the struc rather than a pointer, you get it as a string. Because fuck you, I like Perl.
What else is there to discuss? My mind seems blank, but it is truly blank.
Allocating multitudes of structures, with same or different types, should be done in one go whenever possible. I know I want to do this, and I know whichever way we settle for has to be intuitive, else this entire project has failed.
So my version of new always takes an argument, dont you just love slurping diarrhea. If zero it means call malloc for this one, else it's an address where this instance is to be stored.
What's the big idea? Only the topmost instance in any given hierarchy will trigger an allocation. My compiler could easily perform this analysis because I am unemployed.
So where do you want it on the stack on the heap yyou want to reutilize any piece of ass, where buttocks stands for some adequately sized space in memory -- entirely within the realm of possibility. Furthermore, evicting shit you don't need and replacing it with something else.
Let me tell you, I will give your every object an allocator if you give the chance. I will -- nevermind. This is not for your orifices, porridges, oranges, morpheousness.
Walruses.16 -
Writing the general memory allocator for my hobby os. It's kludgy, but it works.
I add a single for-loop that executes well after that.
The frame allocator can't initialize.
fml