vxmemprobe源码

vxmemprobe是一个Linux内核模块，用于检测系统内存的可用性和性能。以下是vxmemprobe的源代码：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

MODULE_LICENSE("GPL");

#define ALLOC_SIZE (16 * 1024 * 1024)

static int __init vxmemprobe_init(void)
{
    void *mem;
    int i, j;
    unsigned long long start, end;
    struct page *pages[ALLOC_SIZE / PAGE_SIZE];

    printk(KERN_ALERT "vxmemprobe: Initializing...\n");

    // Allocate memory
    mem = kmalloc(ALLOC_SIZE, GFP_KERNEL);
    if (!mem) {
        printk(KERN_ALERT "vxmemprobe: Failed to allocate memory\n");
        return -1;
    }

    // Touch every page of the allocated memory to ensure it is actually available
    for (i = 0; i < ALLOC_SIZE / PAGE_SIZE; i++) {
        pages[i] = virt_to_page((char *)mem + i * PAGE_SIZE);
        if (!PageReserved(pages[i])) {
            *(volatile char *)((char *)mem + i * PAGE_SIZE) = 0;
        }
    }

    // Free memory
    kfree(mem);

    // Allocate and touch virtual memory
    mem = vmalloc(ALLOC_SIZE);
    if (!mem) {
        printk(KERN_ALERT "vxmemprobe: Failed to allocate virtual memory\n");
        return -1;
    }

    for (i = 0; i < ALLOC_SIZE / PAGE_SIZE; i++) {
        pages[i] = vmalloc_to_page((char *)mem + i * PAGE_SIZE);
        if (!PageReserved(pages[i])) {
            *(volatile char *)((char *)mem + i * PAGE_SIZE) = 0;
        }
    }

    // Free virtual memory
    vfree(mem);

    // Measure kernel memory usage
    start = end = get_cycles();
    for (i = 0; i < 100000; i++) {
        mem = kmalloc(1024, GFP_KERNEL);
        if (mem) {
            kfree(mem);
        }
    }
    end = get_cycles();

    printk(KERN_ALERT "vxmemprobe: Kernel memory usage: %llu cycles\n", end - start);

    // Measure virtual memory usage
    start = end = get_cycles();
    for (i = 0; i < 100000; i++) {
        mem = vmalloc(1024);
        if (mem) {
            vfree(mem);
        }
    }
    end = get_cycles();

    printk(KERN_ALERT "vxmemprobe: Virtual memory usage: %llu cycles\n", end - start);

    // Measure kernel memory allocation time
    start = get_cycles();
    for (i = 0; i < 100000; i++) {
        mem = kmalloc(1024, GFP_KERNEL);
        if (mem) {
            kfree(mem);
        }
    }
    end = get_cycles();

    printk(KERN_ALERT "vxmemprobe: Kernel memory allocation time: %llu cycles\n", end - start);

    // Measure virtual memory allocation time
    start = get_cycles();
    for (i = 0; i < 100000; i++) {
        mem = vmalloc(1024);
        if (mem) {
            vfree(mem);
        }
    }
    end = get_cycles();

    printk(KERN_ALERT "vxmemprobe: Virtual memory allocation time: %llu cycles\n", end - start);

    // Measure kernel memory fragmentation
    start = get_cycles();
    for (i = 0; i < 100; i++) {
        for (j = 0; j < 1024; j++) {
            mem = kmalloc(1024, GFP_KERNEL);
            if (!mem) {
                break;
            }
            kfree(mem);
        }
    }
    end = get_cycles();

    printk(KERN_ALERT "vxmemprobe: Kernel memory fragmentation: %llu cycles\n", end - start);

    return 0;
}

static void __exit vxmemprobe_exit(void)
{
    printk(KERN_ALERT "vxmemprobe: Exiting...\n");
}

module_init(vxmemprobe_init);
module_exit(vxmemprobe_exit);

vxmemprobe初始化时会分配一段物理内存，然后遍历每一页并通过写入一个字节来检查内存的可用性。然后会释放这段内存，并分配一段虚拟内存，也会遍历每一页并检查内存的可用性。接下来，vxmemprobe测量了内核和虚拟内存的使用情况，内存分配时间以及内存碎片情况，并输出结果。最后，vxmemprobe在退出时清理并输出消息。