I've been running some performance tests on a single-threaded workload using stress-ng and monitoring the results with perf stat. I noticed that binding the process to a specific CPU core using taskset results in significantly more cache misses compared to running it without setting CPU affinity. Example:

Without affinity:

• Migrations: 1
• Context-switches: 1
• Cache Misses: 10,010
• Cache Miss Rate: 31.376%
• Cycles: 1,796,855
• Instructions: 2,385,959

With taskset -c 20:

• Migrations: 0
• Contex-switches: 1
• Cache Misses: 13,029
• Cache Miss Rate: 65.840%
• Cycles: 2,495,645
• Instructions: 2,539,112

Run script example:

taskset -c 20 stress-ng --cpu 1 --cpu-load 100 --timeout 12s &
PROCESS_PID=$!
sudo perf stat -e migrations,context-switches,cache-misses,cycles,instructions,cache-references -p $PROCESS_PID

The core 20 is aribrary (I checked others), free, not isolated.

Any ideas why I get more cache misses when isolate workload? I'd expect rather less cache misses.

OS: Ubuntu 20.04

CPU: Intel Core i9-10980XE, no NUMA.

Thanks!

Hello,

I graduated with a bachelor's and master's degree in computer science. I have been working as a professional backend developer for about 2 years. I work with Java and Spring boot at work. But what I have wanted to do since my childhood is to work with languages ​​such as C/C++/Assembly. Do you think I should or can I work as an embedded developer? I am 25 years old and I already have advanced knowledge of C and C++. Am I too late for such a domain change or is it right to switch to embedded development just to work in C? Thank you very much in advance for your answers.

Posting here to see if anyone knows of any documentation for the DS-01 compression algorithm. This is a legacy compression algorithm for DMSDOS compressed FAT filesystems.

I have the emails from one "pali" who wrote the only DS-01 decompression implementation I can find.

I really got no idea. Can you guys give me some discord servers, groups, etc.

Or dm me if you want to :D

Being a CS student and after doing web dev for some time, I'm starting to realize how much abstraction the modern day programming and software dev in general provides. This is good in its own ways, no need to "reinvent the wheel" and it's good that software can be shipped fast without deep diving into low level stuffs.

But I just can't help but just wanna know about how we got here, how the things that I use work underneath. How things are built ground up. I know a bit about hardware and I'll leave it to that. I'm more into the software part.

So to get into low level programming and understanding a "Computer" better, I just decided to make an OS from scratch.

I know some x86 and 8085 assembly, microprocessor and computer architecture basics, some C programming, and OS theories like process scheduling, paging, virtual memory.

Am I qualified enough to be going down this path?

Also, what would be the right approach to do it and what are some good resources that I could get online?

I've checked out the OSdev wiki, and a youtube playlist from nanobyte so far.

So the IEEE club of my university offered me to do do a research and lead a research team on any subject. The common topic for research would be AI and ML but i have decent knowledge of reverse engineering and low level stuff so i wanted to work on this subject rather than AI and ML.

So i am looking for suggestions on what unique thing I can explore and research in reverse engineering. I searched online and most of the stuff related to RE is related to malware analysis, I am also open for that idea but I first need to know my goal exactly so here I am asking for help from reddit gods. I have experience with exploring malicious stuff with volatility but again I want something unqiue with a good learning outcome so that the paper actually gets published.

One idea that has been in my mind was on reverse engineering self modifying binaries, but just analysis binaries with a RE framework won't be enough so I wanted to extend this by adding some more things into it like if I have a binary that injects shellcode during runtime and then modifies that shellcode etc etc. So pls suggestions are welcomed.

Trying to learn how this works, is it possible to decrypt it somehow and turn it back to text?

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Hi,

Do you know how I could possible take a different (but same) microsoft dongle, and change the frequency to match my mouse? and how do I even check that frequency?

Even if not necessary and i can just buy a new one, this seems like a fun DIY project.

Would love some help, thanks :)

​

P.S. the mouse is the microsoft ergonomic sculpt mouse.

My nasm program crashes

So, I think I understand what's going on. The program after the call to main jumps to address 0, which is obviously invalid. Which tells that ret is popping 0 (the top of the stack) into rip. But how is 0 to the top of the stack in this instance?

global _start

section .text
_start:
   call main
   
   xor  rdi, rdi
   xor  rsi, rsi
   mov  rax, 60
   syscall
   
main:
    push    rbp
    mov     rbp,rsp

    mov     rdi, msg
    call    print

    mov     rsp, rbp
    pop     rbp
    ret
    
print:
    push    rbp
    mov     rbp,rsp
    sub     rsp, 0x8

    mov     [rbp], rdi
    mov     rax, [rbp]
    mov     rsi, rax
    mov     rdi, 1
    mov     rbx, 7
    mov     rax, 1
    syscall

    mov     rsp, rbp
    pop     rbp
    ret

section .data
    msg: db "aaaaa",100