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linux: improve /proc/cpuinfo parser

Make uv_cpu_info() understand the ARM and MIPS versions of /proc/cpuinfo,
it only knew how to deal with the x86 version

This commit also fixes a buglet where uv_cpu_info() reported the maximum CPU
frequency instead of the actual CPU frequency. That is, before this commit
`out/Debug/run-tests platform_output | grep speed | sort | uniq -c` on my
system always reported:

      8   speed: 3400

Now it reports (for example):

      2   speed: 3400
      6   speed: 1600

In other words, two CPUs are running at full speed while the others have been
scaled back because they're mostly idle.

Fixes #526.
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bnoordhuis committed Aug 14, 2012
1 parent f4f294f commit 54bfb66806a3f94f44243030ad51a10db6c9eb29
Showing with 155 additions and 68 deletions.
  1. +155 −68 src/unix/linux/linux-core.c
@@ -63,6 +63,11 @@ static struct {
size_t len;
} process_title;

static void read_models(unsigned int numcpus, uv_cpu_info_t* ci);
static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci);
static void read_times(unsigned int numcpus, uv_cpu_info_t* ci);
static unsigned long read_cpufreq(unsigned int cpunum);


uint64_t uv_hrtime() {
struct timespec ts;
@@ -297,81 +302,163 @@ uv_err_t uv_uptime(double* uptime) {


uv_err_t uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {
unsigned int ticks = (unsigned int)sysconf(_SC_CLK_TCK),
multiplier = ((uint64_t)1000L / ticks), cpuspeed;
int numcpus = 0, i = 0;
unsigned long ticks_user, ticks_sys, ticks_idle, ticks_nice, ticks_intr;
char line[512], speedPath[256], model[512];
FILE *fpStat = fopen("/proc/stat", "r");
FILE *fpModel = fopen("/proc/cpuinfo", "r");
FILE *fpSpeed;
uv_cpu_info_t* cpu_info;

if (fpModel) {
while (fgets(line, 511, fpModel) != NULL) {
if (strncmp(line, "model name", 10) == 0) {
numcpus++;
if (numcpus == 1) {
char *p = strchr(line, ':') + 2;
strcpy(model, p);
model[strlen(model)-1] = 0;
}
} else if (strncmp(line, "cpu MHz", 7) == 0) {
if (numcpus == 1) {
sscanf(line, "%*s %*s : %u", &cpuspeed);
}
}
}
fclose(fpModel);
}
unsigned int numcpus;
uv_cpu_info_t* ci;

*cpu_infos = (uv_cpu_info_t*)malloc(numcpus * sizeof(uv_cpu_info_t));
if (!(*cpu_infos)) {
return uv__new_artificial_error(UV_ENOMEM);
}
*cpu_infos = NULL;
*count = 0;

numcpus = sysconf(_SC_NPROCESSORS_ONLN);
assert(numcpus != (unsigned int) -1);
assert(numcpus != 0);

ci = calloc(numcpus, sizeof(*ci));
if (ci == NULL)
return uv__new_sys_error(ENOMEM);

read_speeds(numcpus, ci);
read_models(numcpus, ci);
read_times(numcpus, ci);

*cpu_infos = ci;
*count = numcpus;

cpu_info = *cpu_infos;

if (fpStat) {
while (fgets(line, 511, fpStat) != NULL) {
if (strncmp(line, "cpu ", 4) == 0) {
continue;
} else if (strncmp(line, "cpu", 3) != 0) {
break;
}

sscanf(line, "%*s %lu %lu %lu %lu %*s %lu",
&ticks_user, &ticks_nice, &ticks_sys, &ticks_idle, &ticks_intr);
snprintf(speedPath, sizeof(speedPath),
"/sys/devices/system/cpu/cpu%u/cpufreq/cpuinfo_max_freq", i);

fpSpeed = fopen(speedPath, "r");

if (fpSpeed) {
if (fgets(line, 511, fpSpeed) != NULL) {
sscanf(line, "%u", &cpuspeed);
cpuspeed /= 1000;
}
fclose(fpSpeed);
}

cpu_info->cpu_times.user = ticks_user * multiplier;
cpu_info->cpu_times.nice = ticks_nice * multiplier;
cpu_info->cpu_times.sys = ticks_sys * multiplier;
cpu_info->cpu_times.idle = ticks_idle * multiplier;
cpu_info->cpu_times.irq = ticks_intr * multiplier;

cpu_info->model = strdup(model);
cpu_info->speed = cpuspeed;

cpu_info++;
return uv_ok_;
}


static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci) {
unsigned int num;

for (num = 0; num < numcpus; num++)
ci[num].speed = read_cpufreq(num) / 1000;
}


static void read_models(unsigned int numcpus, uv_cpu_info_t* ci) {
#if defined(__i386__) || defined(__x86_64__)
static const char marker[] = "model name\t: ";
#elif defined(__arm__)
static const char marker[] = "Processor\t: ";
#elif defined(__mips__)
static const char marker[] = "cpu model\t\t: ";
#else
# warning uv_cpu_info() is not supported on this architecture.
static const char marker[] = "(dummy)";
#endif
unsigned int num;
char buf[1024];
char* model;
FILE* fp;

fp = fopen("/proc/cpuinfo", "r");
if (fp == NULL)
return;

num = 0;

while (fgets(buf, sizeof(buf), fp)) {
if (num >= numcpus)
break;

if (strncmp(buf, marker, sizeof(marker) - 1))
continue;

model = buf + sizeof(marker) - 1;
model = strndup(model, strlen(model) - 1); /* strip newline */
ci[num++].model = model;
}
fclose(fp);
}


static void read_times(unsigned int numcpus, uv_cpu_info_t* ci) {
unsigned long clock_ticks;
struct uv_cpu_times_s ts;
unsigned long user;
unsigned long nice;
unsigned long sys;
unsigned long idle;
unsigned long dummy;
unsigned long irq;
unsigned int num;
unsigned int len;
char buf[1024];
FILE* fp;

clock_ticks = sysconf(_SC_CLK_TCK);
assert(clock_ticks != (unsigned long) -1);
assert(clock_ticks != 0);

fp = fopen("/proc/stat", "r");
if (fp == NULL)
return;

if (!fgets(buf, sizeof(buf), fp))
abort();

num = 0;

while (fgets(buf, sizeof(buf), fp)) {
if (num >= numcpus)
break;

if (strncmp(buf, "cpu", 3))
break;

/* skip "cpu<num> " marker */
{
unsigned int n = num;
for (len = sizeof("cpu0"); n /= 10; len++);
assert(sscanf(buf, "cpu%u ", &n) == 1 && n == num);
}
fclose(fpStat);

/* Line contains user, nice, system, idle, iowait, irq, softirq, steal,
* guest, guest_nice but we're only interested in the first four + irq.
*
* Don't use %*s to skip fields or %ll to read straight into the uint64_t
* fields, they're not allowed in C89 mode.
*/
if (6 != sscanf(buf + len,
"%lu %lu %lu %lu %lu %lu",
&user,
&nice,
&sys,
&idle,
&dummy,
&irq))
abort();

ts.user = clock_ticks * user;
ts.nice = clock_ticks * nice;
ts.sys = clock_ticks * sys;
ts.idle = clock_ticks * idle;
ts.irq = clock_ticks * irq;
ci[num++].cpu_times = ts;
}
fclose(fp);
}

return uv_ok_;

static unsigned long read_cpufreq(unsigned int cpunum) {
unsigned long val;
char buf[1024];
FILE* fp;

snprintf(buf,
sizeof(buf),
"/sys/devices/system/cpu/cpu%u/cpufreq/scaling_cur_freq",
cpunum);

fp = fopen(buf, "r");
if (fp == NULL)
return 0;

val = 0;
fscanf(fp, "%lu", &val);
fclose(fp);

return val;
}


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