nmeter: stop using data/bss; reduce amount of reads from /proc
# size */*/nmeter.o
text data bss dec hex filename
4366 80 16 4462 116e busybox.t0/miscutils/nmeter.o
4386 0 0 4386 1122 busybox.t2/miscutils/nmeter.o
diff --git a/miscutils/nmeter.c b/miscutils/nmeter.c
index e15cc8c..3152b74 100644
--- a/miscutils/nmeter.c
+++ b/miscutils/nmeter.c
@@ -17,33 +17,67 @@
typedef unsigned long long ullong;
-enum { proc_file_size = 4096 };
+enum { PROC_FILE_SIZE = 4096 };
typedef struct proc_file {
- const char *name;
- int gen;
char *file;
+ //const char *name;
+ smallint last_gen;
} proc_file;
-static proc_file proc_stat = { "/proc/stat", -1 };
-static proc_file proc_loadavg = { "/proc/loadavg", -1 };
-static proc_file proc_net_dev = { "/proc/net/dev", -1 };
-static proc_file proc_meminfo = { "/proc/meminfo", -1 };
-static proc_file proc_diskstats = { "/proc/diskstats", -1 };
-// Sample #
-static int gen = -1;
-// Linux 2.6? (otherwise assumes 2.4)
-static int is26 = 0;
-static struct timeval tv;
-static int delta = 1000000;
-static int deltanz = 1000000;
-static int need_seconds = 0;
-static const char *final_str = "\n";
+static const char *const proc_name[] = {
+ "stat", // Must match the order of proc_file's!
+ "loadavg",
+ "net/dev",
+ "meminfo",
+ "diskstats",
+ "sys/fs/file-nr",
+};
+
+struct globals {
+ // Sample generation flip-flop
+ smallint gen;
+ // Linux 2.6? (otherwise assumes 2.4)
+ smallint is26;
+ // 1 if sample delay is not an integer fraction of a second
+ smallint need_seconds;
+ char *cur_outbuf;
+ const char *final_str;
+ int delta;
+ int deltanz;
+ struct timeval tv;
+#define first_proc_file proc_stat
+ proc_file proc_stat; // Must match the order of proc_name's!
+ proc_file proc_loadavg;
+ proc_file proc_net_dev;
+ proc_file proc_meminfo;
+ proc_file proc_diskstats;
+ proc_file proc_sys_fs_filenr;
+};
+#define G (*ptr_to_globals)
+#define gen (G.gen )
+#define is26 (G.is26 )
+#define need_seconds (G.need_seconds )
+#define cur_outbuf (G.cur_outbuf )
+#define final_str (G.final_str )
+#define delta (G.delta )
+#define deltanz (G.deltanz )
+#define tv (G.tv )
+#define proc_stat (G.proc_stat )
+#define proc_loadavg (G.proc_loadavg )
+#define proc_net_dev (G.proc_net_dev )
+#define proc_meminfo (G.proc_meminfo )
+#define proc_diskstats (G.proc_diskstats )
+#define proc_sys_fs_filenr (G.proc_sys_fs_filenr)
// We depend on this being a char[], not char* - we take sizeof() of it
#define outbuf bb_common_bufsiz1
-static char *cur_outbuf = outbuf;
+#define INIT_G() do { \
+ cur_outbuf = outbuf; \
+ final_str = "\n"; \
+ deltanz = delta = 1000000; \
+ } while (0)
static inline void reset_outbuf(void)
{
@@ -85,27 +119,31 @@
put_c('?');
}
-static int readfile_z(char *buf, int sz, const char* fname)
+static void readfile_z(char *buf, int sz, const char* fname)
{
- sz = open_read_close(fname, buf, sz-1);
- if (sz < 0) {
- buf[0] = '\0';
- return 1;
+// open_read_close() will do two reads in order to be sure we are at EOF,
+// and we don't need/want that.
+// sz = open_read_close(fname, buf, sz-1);
+
+ int fd = xopen(fname, O_RDONLY);
+ buf[0] = '\0';
+ if (fd >= 0) {
+ sz = read(fd, buf, sz-1);
+ if (sz > 0) buf[sz] = '\0';
+ close(fd);
}
- buf[sz] = '\0';
- return 0;
}
static const char* get_file(proc_file *pf)
{
- if (pf->gen != gen) {
- pf->gen = gen;
- // We allocate proc_file_size bytes. This wastes memory,
+ if (pf->last_gen != gen) {
+ pf->last_gen = gen;
+ // We allocate PROC_FILE_SIZE bytes. This wastes memory,
// but allows us to allocate only once (at first sample)
// per proc file, and reuse buffer for each sample
if (!pf->file)
- pf->file = xmalloc(proc_file_size);
- readfile_z(pf->file, proc_file_size, pf->name);
+ pf->file = xmalloc(PROC_FILE_SIZE);
+ readfile_z(pf->file, PROC_FILE_SIZE, proc_name[pf - &first_proc_file]);
}
return pf->file;
}
@@ -242,10 +280,10 @@
static s_stat* init_delay(const char *param)
{
- delta = strtol(param, NULL, 0)*1000;
+ delta = bb_strtoi(param, NULL, 0) * 1000;
deltanz = delta > 0 ? delta : 1;
need_seconds = (1000000%deltanz) != 0;
- return (s_stat*)0;
+ return NULL;
}
static s_stat* init_cr(const char *param)
@@ -281,7 +319,7 @@
return;
}
- for (i=0; i<CPU_FIELDCNT; i++) {
+ for (i = 0; i < CPU_FIELDCNT; i++) {
ullong old = s->old[i];
if (data[i] < old) old = data[i]; //sanitize
s->old[i] = data[i];
@@ -289,7 +327,7 @@
}
if (all) {
- for (i=0; i<CPU_FIELDCNT; i++) {
+ for (i = 0; i < CPU_FIELDCNT; i++) {
ullong t = bar_sz * data[i];
norm_all += data[i] = t / all;
frac[i] = t % all;
@@ -298,7 +336,7 @@
while (norm_all < bar_sz) {
unsigned max = frac[0];
int pos = 0;
- for (i=1; i<CPU_FIELDCNT; i++) {
+ for (i = 1; i < CPU_FIELDCNT; i++) {
if (frac[i] > max) max = frac[i], pos = i;
}
frac[pos] = 0; //avoid bumping up same value twice
@@ -640,11 +678,9 @@
static void collect_fd(fd_stat *s)
{
- char file[4096];
ullong data[2];
- readfile_z(file, sizeof(file), "/proc/sys/fs/file-nr");
- if (rdval(file, "", data, 1, 2)) {
+ if (rdval(get_file(&proc_sys_fs_filenr), "", data, 1, 2)) {
put_question_marks(4);
return;
}
@@ -702,7 +738,7 @@
static void collect_info(s_stat *s)
{
- gen++;
+ gen ^= 1;
while (s) {
put(s->label);
s->collect(s);
@@ -714,7 +750,7 @@
typedef s_stat* init_func(const char *param);
static const char options[] = "ncmsfixptbdr";
-static init_func* init_functions[] = {
+static init_func *const init_functions[] = {
init_if,
init_cpu,
init_mem,
@@ -738,10 +774,15 @@
s_stat *s;
char *cur, *prev;
+ PTR_TO_GLOBALS = xzalloc(sizeof(G));
+ INIT_G();
+
+ xchdir("/proc");
+
if (argc != 2)
bb_show_usage();
- if (open_read_close("/proc/version", buf, sizeof(buf)) > 0)
+ if (open_read_close("version", buf, sizeof(buf)) > 0)
is26 = (strstr(buf, " 2.4.")==NULL);
// Can use argv[1] directly, but this will mess up
@@ -750,11 +791,11 @@
while (1) {
char *param, *p;
prev = cur;
-again:
+ again:
cur = strchr(cur, '%');
if (!cur)
break;
- if (cur[1]=='%') { // %%
+ if (cur[1] == '%') { // %%
strcpy(cur, cur+1);
cur++;
goto again;
@@ -813,12 +854,12 @@
collect_info(first);
reset_outbuf();
if (delta >= 0) {
- gettimeofday(&tv, 0);
+ gettimeofday(&tv, NULL);
usleep(delta > 1000000 ? 1000000 : delta - tv.tv_usec%deltanz);
}
while (1) {
- gettimeofday(&tv, 0);
+ gettimeofday(&tv, NULL);
collect_info(first);
put(final_str);
print_outbuf();
@@ -831,9 +872,9 @@
if (delta >= 0) {
int rem;
// can be commented out, will sacrifice sleep time precision a bit
- gettimeofday(&tv, 0);
+ gettimeofday(&tv, NULL);
if (need_seconds)
- rem = delta - ((ullong)tv.tv_sec*1000000+tv.tv_usec)%deltanz;
+ rem = delta - ((ullong)tv.tv_sec*1000000 + tv.tv_usec) % deltanz;
else
rem = delta - tv.tv_usec%deltanz;
// Sometimes kernel wakes us up just a tiny bit earlier than asked
@@ -845,5 +886,5 @@
}
}
- return 0;
+ /*return 0;*/
}