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上篇文章对meminfo里的信息做出简单的解释了那么内核怎么把meminfo信息动态反应到meminfo文件中呢在内核 linux/fs/proc/proc_misc.c中
static int meminfo_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
struct sysinfo i;
int len;
unsigned long committed;
unsigned long
allowed;
struct vmalloc_info vmi;
long cached;
#define K(x) ((x)
si_meminfo(&i);
si_swapinfo(&i);
//这两个函数是对struct sysinfo结构进行初始化的
committed = atomic_read(&vm_committed_space);
allowed = ((totalram_pages - hugetlb_total_pages())
* sysctl_overcommit_ratio / 100) + total_swap_pages;
//其中这项根据上篇文章CommitLimit解释计算的
cached = global_page_state(NR_FILE_PAGES) -
total_swapcache_pages - i.bufferram;
if (cached
cached = 0;
get_vmalloc_info(&vmi);
/*
* Tagged format, for easy grepping and expansion.
*/
len = sprintf(page,
"MemTotal: %8lu kB\n"
"MemFree: %8lu kB\n"
"Buffers: %8lu kB\n"
"Cached: %8lu kB\n"
"SwapCached: %8lu kB\n"
"Active: %8lu kB\n"
"Inactive: %8lu kB\n"
#ifdef CONFIG_HIGHMEM
"HighTotal: %8lu kB\n"
"HighFree: %8lu kB\n"
"LowTotal: %8lu kB\n"
"LowFree: %8lu kB\n"
#endif
"SwapTotal: %8lu kB\n"
"SwapFree: %8lu kB\n"
"Dirty: %8lu kB\n"
"Writeback: %8lu kB\n"
"AnonPages: %8lu kB\n"
"Mapped: %8lu kB\n"
"Slab: %8lu kB\n"
"SReclaimable: %8lu kB\n"
"SUnreclaim: %8lu kB\n"
"PageTables: %8lu kB\n"
"NFS_Unstable: %8lu kB\n"
"Bounce: %8lu kB\n"
"CommitLimit: %8lu kB\n"
"Committed_AS: %8lu kB\n"
"VmallocTotal: %8lu kB\n"
"VmallocUsed: %8lu kB\n"
"VmallocChunk: %8lu kB\n",
K(i.totalram),
K(i.freeram),
K(i.bufferram),
K(cached),
K(total_swapcache_pages),
K(global_page_state(NR_ACTIVE)),
K(global_page_state(NR_INACTIVE)),
#ifdef CONFIG_HIGHMEM
K(i.totalhigh),
K(i.freehigh),
K(i.totalram-i.totalhigh),
K(i.freeram-i.freehigh),
#endif
K(i.totalswap),
K(i.freeswap),
K(global_page_state(NR_FILE_DIRTY)),
K(global_page_state(NR_WRITEBACK)),
K(global_page_state(NR_ANON_PAGES)),
K(global_page_state(NR_FILE_MAPPED)),
K(global_page_state(NR_SLAB_RECLAIMABLE) +
global_page_state(NR_SLAB_UNRECLAIMABLE)),
K(global_page_state(NR_SLAB_RECLAIMABLE)),
K(global_page_state(NR_SLAB_UNRECLAIMABLE)),
K(global_page_state(NR_PAGETABLE)),
K(global_page_state(NR_UNSTABLE_NFS)),
K(global_page_state(NR_BOUNCE)),
K(allowed),
K(committed),
(unsigned long)VMALLOC_TOTAL >> 10,
vmi.used >> 10,
vmi.largest_chunk >> 10
);
len += hugetlb_report_meminfo(page + len);
return proc_calc_metrics(page, start, off, count, eof, len);
#undef K
}其中sysinfo结构在 linux/kernel.h 定义:
struct sysinfo {
long uptime; /* 启动到现在经过的时间 */
unsigned long loads[3];
/* 1, 5, and 15 minute load averages */
unsigned long totalram; /* 总的可用的内存大小 */
unsigned long freeram; /* 还未被使用的内存大小 */
unsigned long sharedram; /* 共享的存储器的大小*/
unsigned long bufferram; /* 的存储器的大小 */
unsigned long totalswap; /* 交换区大小 */
unsigned long freeswap; /* 还可用的交换区大小 */
unsigned short procs; /* 当前进程数目 */
unsigned short pad; /* explicit padding for m68k */
unsigned long totalhigh; /* 总的高内存大小 */
unsigned long freehigh; /* 可用的高内存大小 */
unsigned int mem_unit; /* 以字节为单位的内存大小 */
char _f[20-2*sizeof(long)-sizeof(int)];
/* libc5的补丁
};
而global_page_state()函数中的常量定义在 linux/mmzone.h
enum zone_stat_item {
/* First 128 byte cacheline (assuming 64 bit words) */
NR_FREE_PAGES,
NR_INACTIVE,
NR_ACTIVE,
NR_ANON_PAGES, /* Mapped anonymous pages */
NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
only modified from process context */
NR_FILE_PAGES,
NR_FILE_DIRTY,
NR_WRITEBACK,
/* Second 128 byte cacheline */
NR_SLAB_RECLAIMABLE,
NR_SLAB_UNRECLAIMABLE,
NR_PAGETABLE, /* used for pagetables */
NR_UNSTABLE_NFS, /* NFS unstable pages */
NR_BOUNCE,
NR_VMSCAN_WRITE,
#ifdef CONFIG_NUMA
NUMA_HIT, /* allocated in intended node */
NUMA_MISS, /* allocated in non intended node */
NUMA_FOREIGN, /* was intended here, hit elsewhere */
NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
NUMA_LOCAL, /* allocation from local node */
NUMA_OTHER, /* allocation from other node */
#endif
NR_VM_ZONE_STAT_ITEMS }; 其中通过global_page_state()函数根据 zone_stat_item 结构的常量得到不同区大小,会跟 vm_stat[NR_VM_ZONE_STAT_ITEMS]对应起来。vm_stat[]是统计各区的大小。内核 linux/vmstat.h定义:static inline unsigned long global_page_state(enum zone_stat_item item) { long x = atomic_long_read(&vm_stat[item]);#ifdef CONFIG_SMP if (x x = 0;#endif return x;}
下面在 http://hi.baidu.com/realxfliu/blog/item/3dcd1cf7b80a1722730eec23.html 中摘抄了例子..
#include
#include /* 包含调用 _syscallX 宏等相关信息*/
#include /* 包含sysinfo结构体信息*/
int main(int argc, char *agrv[])
{
struct sysinfo s_info;
int error;
error = sysinfo(&s_info);
printf("\n\ncode error=%d\n",error);
printf("Uptime = %ds\nLoad: 1 min%d / 5 min %d / 15 min %d\n"
"RAM: total %d / free %d /shared%d\n"
"Memory in buffers = %d\nSwap:total%d/free%d\n"
"Number of processes = %d\n",
s_info.uptime, s_info.loads[0],
s_info.loads[1], s_info.loads[2],
s_info.totalram, s_info.freeram,
s_info.totalswap, s_info.freeswap,
s_info.procs);
return 0;
}
结果:
code error=0
Uptime = 8329s
Load: 1 min37152 / 5 min 37792 / 15 min 48672
RAM: total 519659520 / free 9031680 /shared1003474944
Memory in buffers = 937451520
Swap:total223/free-1078732672
Number of processes = -1078732608
本文来自ChinaUnix博客,如果查看原文请点:http://blog.chinaunix.net/u1/55599/showart_1351106.html |
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