Can I find out the cache size (in lines) within the C/C++ program?

Asked 2 years ago, Updated 2 years ago, 83 views

Please tell me the code to find out the cache size (in line units) in the C/C++ program.

My computer uses Linux and I would appreciate it if you could tell me the other platform code.

It would be nice if it was a code that can be used on all platforms, but it would be impossible, right?

c c++ caching system-programming operating-system

2022-09-21 21:01

1 Answers

GitHub - CacheLineSize code imported (available on multi-platform)

#ifndef GET_CACHE_LINE_SIZE_H_INCLUDED
#define GET_CACHE_LINE_SIZE_H_INCLUDED

// // Author: Nick Strupat
// // Date: October 29, 2010
// // Returns the cache line size (in bytes) of the processor, or 0 on failure

#include <stddef.h>
size_t cache_line_size();

#if defined(__APPLE__)

#include <sys/sysctl.h>
size_t cache_line_size() {
    size_t line_size = 0;
    size_t sizeof_line_size = sizeof(line_size);
    sysctlbyname("hw.cachelinesize", &line_size, &sizeof_line_size, 0, 0);
    return line_size;
}

#elif defined(_WIN32)

#include <stdlib.h>
#include <windows.h>
size_t cache_line_size() {
    size_t line_size = 0;
    DWORD buffer_size = 0;
    DWORD i = 0;
    SYSTEM_LOGICAL_PROCESSOR_INFORMATION * buffer = 0;

    GetLogicalProcessorInformation(0, &buffer_size);
    buffer = (SYSTEM_LOGICAL_PROCESSOR_INFORMATION *)malloc(buffer_size);
    GetLogicalProcessorInformation(&buffer[0], &buffer_size);

    for (i = 0; i != buffer_size / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION); ++i) {
        if (buffer[i].Relationship == RelationCache && buffer[i].Cache.Level == 1) {
            line_size = buffer[i].Cache.LineSize;
            break;
        }
    }

    free(buffer);
    return line_size;
}

#elif defined(linux)

#include <stdio.h>
size_t cache_line_size() {
    FILE * p = 0;
    p = fopen("/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size", "r");
    unsigned int i = 0;
    if (p) {
        fscanf(p, "%d", &i);
        fclose(p);
    }
    return i;
}

#else
#error Unrecognized platform
#endif

#endif


2022-09-21 21:01

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