# 討論筆記

## 2025/06/11
### 閱讀
- 事件驅動伺服器
- 並行程式設計

### 使用 NixOS 公司
[Ref](https://github.com/ad-si/nix-companies)
[Ref](https://planetnix.com/speakers/#aneesh-agrawal)

| 公司名稱 | 團隊 | 國家 |
| -------- | -------- | -------- |
| Google | Firebase studio | USA |
| [Shopify](https://shopify.engineering/shipit-presents-how-shopify-uses-nix)| | USA|
|Replit||USA|
|[D.E Shaw](https://discourse.nixos.org/t/the-d-e-shaw-group-quant-systems-build-and-release-engineer/13686)|[Flox](https://jobs.ashbyhq.com/flox/b98c4b25-aeb6-4474-9da5-5ff1efe4e841)|USA|
|[Arista Network](https://github.com/aristanetworks/nix-serve-ng)||USA|
|[Anduril](https://discourse.nixos.org/t/nixcon-na-2024-is-getting-sponsored-by-anduril-what-to-do-about-it/41258)||USA|
|Anthropic||USA|
|Mercury.com||USA|

### eBPF socket轉發專案

#### 測試程式偶爾會有找不到該找的鍵值
解決方法: 增加一個usleep在發送send()函數之前
驗證過程：增加bpf_printk, tcpdump, 更改鍵值大小

猜測：可能是ebpf從未更新快取拿到資料

#### 卸載ebpf程式必須是斷網狀態
理由：只要持續有封包就會使得程式無法完整釋放資源

#### 實驗結果

結論：ktcp略優於ebpf [連結](https://github.com/Brianpan/ebpf-tcp-server/blob/main/benchmark)

| 對象 | 平均數 | 標準差 |
| -------- | -------- | -------- |
| kecho | 479 | 371 |
| tcp-ebpf| 591|437|


##### 環境

uname -a
Linux brianpan-Aspire-A14-52MT 6.11.0-17-generic #17~24.04.2-Ubuntu SMP PREEMPT_DYNAMIC Mon Jan 20 22:48:29 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

gcc --version
gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

sudo lscpu
Architecture:             x86_64
  CPU op-mode(s):         32-bit, 64-bit
  Address sizes:          42 bits physical, 48 bits virtual
  Byte Order:             Little Endian
CPU(s):                   8
  On-line CPU(s) list:    0-7
Vendor ID:                GenuineIntel
  BIOS Vendor ID:         Intel(R) Corporation
  Model name:             Intel(R) Core(TM) Ultra 5 226V
    BIOS Model name:      Intel(R) Core(TM) Ultra 5 226V To Be Filled By O.E.M. 
                          CPU @ 0.4GHz
    BIOS CPU family:      773
    CPU family:           6
    Model:                189
    Thread(s) per core:   1
    Core(s) per socket:   8
    Socket(s):            1
    Stepping:             1
    CPU(s) scaling MHz:   40%
    CPU max MHz:          4500.0000
    CPU min MHz:          400.0000
    BogoMIPS:             6220.80
    Flags:                fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge m
                          ca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 s
                          s ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc 
                          art arch_perfmon pebs bts rep_good nopl xtopology nons
                          top_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq 
                          dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma c
                          x16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt t
                          sc_deadline_timer aes xsave avx f16c rdrand lahf_lm ab
                          m 3dnowprefetch cpuid_fault epb intel_ppin ssbd ibrs i
                          bpb stibp ibrs_enhanced tpr_shadow flexpriority ept vp
                          id ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms
                           invpcid rdt_a rdseed adx smap clflushopt clwb intel_p
                          t sha_ni xsaveopt xsavec xgetbv1 xsaves split_lock_det
                          ect user_shstk avx_vnni lam wbnoinvd dtherm ida arat p
                          ln pts hwp hwp_notify hwp_act_window hwp_epp hwp_pkg_r
                          eq hfi vnmi umip pku ospke waitpkg gfni vaes vpclmulqd
                          q rdpid bus_lock_detect movdiri movdir64b fsrm md_clea
                          r serialize pconfig arch_lbr ibt flush_l1d arch_capabi
                          lities
Virtualization features:  
  Virtualization:         VT-x
Caches (sum of all):      
  L1d:                    320 KiB (8 instances)
  L1i:                    512 KiB (8 instances)
  L2:                     14 MiB (5 instances)
  L3:                     8 MiB (1 instance)
NUMA:                     
  NUMA node(s):           1
  NUMA node0 CPU(s):      0-7
Vulnerabilities:          
  Gather data sampling:   Not affected
  Itlb multihit:          Not affected
  L1tf:                   Not affected
  Mds:                    Not affected
  Meltdown:               Not affected
  Mmio stale data:        Not affected
  Reg file data sampling: Not affected
  Retbleed:               Not affected
  Spec rstack overflow:   Not affected
  Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prct
                          l
  Spectre v1:             Mitigation; usercopy/swapgs barriers and __user pointe
                          r sanitization
  Spectre v2:             Mitigation; Enhanced / Automatic IBRS; IBPB conditiona
                          l; RSB filling; PBRSB-eIBRS Not affected; BHI Not affe
                          cted
  Srbds:                  Not affected
  Tsx async abort:        Not affected

### 點子
- haproxy spoe engine with xdp to detect ai traffic
- 利用VXLAN概念,用ebpf達到快速轉發

### 筆記
https://github.com/sysprog21/kecho/blob/master/drop-tcp-socket.c