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https://github.com/nick-lehmann/db-benchmark-rust
Bench for different database storage layers
https://github.com/nick-lehmann/db-benchmark-rust
Last synced: 1 day ago
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Bench for different database storage layers
- Host: GitHub
- URL: https://github.com/nick-lehmann/db-benchmark-rust
- Owner: nick-lehmann
- Created: 2022-06-21T16:33:38.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2022-07-06T16:13:33.000Z (over 2 years ago)
- Last Synced: 2024-11-06T23:06:00.603Z (about 2 months ago)
- Language: Rust
- Size: 48.8 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# DB Benchmark
## Auto-vectorisation
Given the following example:
```rust
pub fn f(a: &[i32; 4], b: &[i32; 4], c: &mut [i32; 4]) {
c[0] = a[0] + b[0]
c[1] = a[1] + b[1]
c[2] = a[2] + b[2]
c[3] = a[3] + b[3]
}
```
The Rust compiler `rustc` provides two direct flags that control auto-vectorisation. However, `rustc` does not do any auto-vectorization on its own but uses LLVM for that. However, `rustc` provides the information to LLVM that allows it to decide which instructions get vectorized.
- [no-vectorize-loops](https://doc.rust-lang.org/rustc/codegen-options/index.html#no-vectorize-loops): If enabled, LLVM tries to unroll loops. [llvm-docs](https://llvm.org/docs/Vectorizers.html#the-loop-vectorizer)
- [no-vectorize-slp](https://doc.rust-lang.org/rustc/codegen-options/index.html#no-vectorize-slp): If enabled, LLVM tries to combine similar independent instructions into SIMD instructions. [llvm-docs](https://llvm.org/docs/Vectorizers.html#the-slp-vectorizer)
[enabled](https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:rust,selection:(endColumn:22,endLineNumber:5,positionColumn:22,positionLineNumber:5,selectionStartColumn:22,selectionStartLineNumber:5,startColumn:22,startLineNumber:5),source:'pub+fn+f(a:+%26%5Bi32%3B+4%5D,+b:+%26%5Bi32%3B+4%5D,+c:+%26mut+%5Bi32%3B+4%5D)+%7B%0A++c%5B0%5D+%3D+a%5B0%5D+%2B+b%5B0%5D%3B%0A++c%5B1%5D+%3D+a%5B1%5D+%2B+b%5B1%5D%3B%0A++c%5B2%5D+%3D+a%5B2%5D+%2B+b%5B2%5D%3B%0A++c%5B3%5D+%3D+a%5B3%5D+%2B+b%5B3%5D%3B%0A%7D%0A'),l:'5',n:'0',o:'Rust+source+%231',t:'0')),k:49.55903684363215,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:r1620,filters:(b:'0',binary:'1',commentOnly:'0',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:rust,libs:!(),options:'-C+opt-level%3D3',selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1,tree:'1'),l:'5',n:'0',o:'rustc+1.62.0+(Rust,+Editor+%231,+Compiler+%231)',t:'0')),k:50.440963156367864,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4)
```asm
example::f:
movdqu xmm0, xmmword ptr [rdi]
movdqu xmm1, xmmword ptr [rsi]
paddd xmm1, xmm0
movdqu xmmword ptr [rdx], xmm1
ret
```
[-no-vectorize-slp](https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:rust,selection:(endColumn:22,endLineNumber:5,positionColumn:22,positionLineNumber:5,selectionStartColumn:22,selectionStartLineNumber:5,startColumn:22,startLineNumber:5),source:'pub+fn+f(a:+%26%5Bi32%3B+4%5D,+b:+%26%5Bi32%3B+4%5D,+c:+%26mut+%5Bi32%3B+4%5D)+%7B%0A++c%5B0%5D+%3D+a%5B0%5D+%2B+b%5B0%5D%3B%0A++c%5B1%5D+%3D+a%5B1%5D+%2B+b%5B1%5D%3B%0A++c%5B2%5D+%3D+a%5B2%5D+%2B+b%5B2%5D%3B%0A++c%5B3%5D+%3D+a%5B3%5D+%2B+b%5B3%5D%3B%0A%7D%0A'),l:'5',n:'0',o:'Rust+source+%231',t:'0')),k:49.55903684363215,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:r1620,filters:(b:'0',binary:'1',commentOnly:'0',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:rust,libs:!(),options:'-C+opt-level%3D3+-C+no-vectorize-slp',selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1,tree:'1'),l:'5',n:'0',o:'rustc+1.62.0+(Rust,+Editor+%231,+Compiler+%231)',t:'0')),k:50.440963156367864,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4)
```asm
example::f:
mov eax, dword ptr [rsi]
add eax, dword ptr [rdi]
mov dword ptr [rdx], eax
mov eax, dword ptr [rsi + 4]
add eax, dword ptr [rdi + 4]
mov dword ptr [rdx + 4], eax
mov eax, dword ptr [rsi + 8]
add eax, dword ptr [rdi + 8]
mov dword ptr [rdx + 8], eax
mov eax, dword ptr [rsi + 12]
add eax, dword ptr [rdi + 12]
mov dword ptr [rdx + 12], eax
ret
```
Since the function does not include a loop, setting `no-vectorize-loops` has no impact.
To make the comparisons fair, we set both `no-vectorize-loops` and `no-vectorize-slp` in our `Cargo.toml`.