C语言中如何获取cacheline的大小
时间: 2024-02-05 09:11:06 浏览: 34
在 C 语言中,获取 cacheline 的大小需要使用特定的操作系统相关的函数或者编译器相关的宏。以下是一些常见的方法:
1. 使用 Linux 系统的 sysconf() 函数获取 cacheline 大小:
```c
#include <unistd.h>
#include <stdio.h>
int main() {
long cacheline_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
printf("cacheline size on this system is %ld bytes\n", cacheline_size);
return 0;
}
```
2. 使用 GCC 编译器的 __builtin_cpu_supports() 函数获取 cacheline 大小:
```c
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
int main() {
bool has_cacheline_size = false;
uint32_t size = 0;
if (__builtin_cpu_supports("avx")) {
size = __builtin_ia32_cpuid_count(0x80000006, 0, &eax, &ebx, &ecx, &edx);
if (size && (eax & 0xff) > 0) {
has_cacheline_size = true;
size = (eax & 0xff) * 64;
}
}
if (has_cacheline_size) {
printf("cacheline size on this system is %u bytes\n", size);
} else {
printf("cannot determine cacheline size on this system\n");
}
return 0;
}
```
注意:这个方法需要编译器支持 AVX 指令集。
3. 使用 Windows 系统的 GetLogicalProcessorInformation() 函数获取 cacheline 大小:
```c
#include <windows.h>
#include <stdio.h>
int main() {
PSYSTEM_LOGICAL_PROCESSOR_INFORMATION buffer = NULL;
DWORD length = 0;
BOOL result = GetLogicalProcessorInformation(buffer, &length);
if (!result && GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
buffer = (PSYSTEM_LOGICAL_PROCESSOR_INFORMATION)malloc(length);
result = GetLogicalProcessorInformation(buffer, &length);
}
if (result) {
DWORD offset = 0;
while (offset < length) {
PSYSTEM_LOGICAL_PROCESSOR_INFORMATION info = buffer + offset / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
if (info->Relationship == RelationCache && info->Cache.Level == 1 && info->Cache.Type == CacheData) {
printf("cacheline size on this system is %u bytes\n", info->Cache.LineSize);
break;
}
offset += sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
}
} else {
printf("cannot determine cacheline size on this system\n");
}
free(buffer);
return 0;
}
```
注意:这个方法需要在 Windows 系统上运行。