Auto Vectorization Test by XOR two regions (4GB)
##Environment:
GCC version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04)
CPU: Intel i7-4700K
##Result(seconds): 1. Method XOR two regions of data with size of 4GB. The minimum unit to XOR are 1Byte(raw), 8Bytes(64), 16Bytes(128), 32Bytes(256) and 32Bytes in the help of Intel AVX2 instruction.
no optimizaiton flags
| raw | 64 | 128 | 256 | 256-avx |
|---|---|---|---|---|
| 10.55 | 0.64 | 0.31 | 0.16 | 0.40 (branchs are the bottleneck) |
-O1
| raw | 64 | 128 | 256 | 256-avx |
|---|---|---|---|---|
| 10.56 | 0.62 | 0.31 | 0.16 | 0.40 |
-O3 -g -Wall -Wextra -mmmx -msse -DINTEL_SSE -msse2 -DINTEL_SSE2 -msse3 -DINTEL_SSE3 -mssse3 -msse4.1 -DINTEL_SSE4 -msse4.2 -DINTEL_SSE4 -mavx -mavx2 -fPIC
| raw | 64 | 128 | 256 | 256-avx |
|---|---|---|---|---|
| 10.54 | 0.63 | 0.31 | 0.16 | 0.40 |
2. Method XOR two regions of data with size from 4KB to 512MB, and the minimum unit to XOR is 4KB.
-O3 -g -Wall -Wextra -mmmx -msse -DINTEL_SSE -msse2 -DINTEL_SSE2 -msse3 -DINTEL_SSE3 -mssse3 -msse4.1 -DINTEL_SSE4 -msse4.2 -DINTEL_SSE4 -mavx -mavx2 -fPIC
| size | raw | avx |
|---|---|---|
| 4KB | 0.692 | 0.034 |
| 8KB | 0.342 | 0.017 |
| 16KB | 0.171 | 0.016 |
| 32KB | 0.085 | 0.016 |
| 64KB | 0.043 | 0.016 |
| 128KB | 0.021 | 0.016 |
| 256KB | 0.011 | 0.015 |
| 512KB | 0.011 | 0.017 |
| 1MB | 0.011 | 0.017 |
| 2MB | 0.011 | 0.017 |
| 4MB | 0.011 | 0.018 |
| 8MB | 0.011 | 0.019 |
| 16MB | 0.011 | 0.019 |
| 32MB | 0.011 | 0.020 |
| 64MB | 0.011 | 0.020 |
| 128MB | 0.011 | 0.024 |
| 256MB | 0.011 | 0.028 |
| 512MB | 0.011 | 0.030 |