让busybox里的free命令可以显示page cache

busybox的free命令不能显示page cache，导致于其功能大打折扣，因为page cache大小很大，在用户申请内存时可以回收，打上如下补丁后，busybox的free命令变得完整：

commit 2219fd301a7f319258ad4be9217cd0d6db9240d4 Author: Barry Song <Baohua.Song@xxx.xxx> Date: Mon Mar 26 11:47:10 2012 +0800 busybox: update free command to include page cache eg. sh-4.2$ free total used free shared buffers cached Mem: 402924 49232 353692 0 668 32160 -/+ buffers/cache: 16404 386520 Swap: 0 0 0 Change-Id: Ic9de9f8cd0051da8fd61ae8238a1d2573587223b Signed-off-by: Barry Song <Baohua.Song@xxx.xxx> diff --git a/procps/free.c b/procps/free.c index efbac5b..6abf1e8 100644 --- a/procps/free.c +++ b/procps/free.c @@ -29,11 +29,35 @@ static unsigned long long scale(unsigned long d) return ((unsigned long long)d * G.mem_unit) >> G_unit_steps; } +static unsigned long get_cache_from_meminfo(void) +{ +#define LINE_LEN 256 + FILE *fp; + char str[LINE_LEN]; + unsigned long long cached; + if((fp = fopen("/proc/meminfo","rt")) == NULL) { + printf("Cantnot open /proc/meminfo"); + exit(1); + } + + while(1) { + fgets(str, LINE_LEN, fp); + if (!strncmp(str, "Cached:", strlen("Cached:"))) + break; + } + + cached = atoi(str + strlen("Cached:")); + + fclose(fp); + + return cached; +} int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM)) { struct sysinfo info; + unsigned long long cached; INIT_G(); @@ -60,43 +84,45 @@ int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM)) #endif sysinfo(&info); + cached = get_cache_from_meminfo(); /* Kernels prior to 2.4.x will return info.mem_unit==0, so cope... */ G.mem_unit = (info.mem_unit ? info.mem_unit : 1); - printf(" %13s%13s%13s%13s%13s\n", + printf(" %13s%13s%13s%13s%13s%13s\n", "total", "used", "free", - "shared", "buffers" /* swap and total don't have these columns */ + "shared", "buffers", "cached" /* swap and total don't have these columns */ /* procps version 3.2.8 also shows "cached" column, but * sysinfo() does not provide this value, need to parse * /proc/meminfo instead and get "Cached: NNN kB" from there. */ ); -#define FIELDS_5 "%13llu%13llu%13llu%13llu%13llu\n" -#define FIELDS_3 (FIELDS_5 + 2*6) -#define FIELDS_2 (FIELDS_5 + 3*6) +#define FIELDS_6 "%13llu%13llu%13llu%13llu%13llu%13llu\n" +#define FIELDS_3 (FIELDS_6 + 3*6) +#define FIELDS_2 (FIELDS_6 + 4*6) - printf("Mem: "); - printf(FIELDS_5, + printf("Mem: "); + printf(FIELDS_6, scale(info.totalram), scale(info.totalram - info.freeram), scale(info.freeram), scale(info.sharedram), - scale(info.bufferram) + scale(info.bufferram), + cached ); /* Show alternate, more meaningful busy/free numbers by counting * buffer cache as free memory (make it "-/+ buffers/cache" * if/when we add support for "cached" column): */ - printf("-/+ buffers: "); + printf("-/+ buffers/cache: "); printf(FIELDS_2, - scale(info.totalram - info.freeram - info.bufferram), - scale(info.freeram + info.bufferram) + scale(info.totalram - info.freeram - info.bufferram) - cached, + scale(info.freeram + info.bufferram) + cached ); #if BB_MMU - printf("Swap:"); + printf("Swap: "); printf(FIELDS_3, scale(info.totalswap), scale(info.totalswap - info.freeswap),