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psi-monitor: Add options to adjust monitoring parameters #401

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Apr 16, 2024
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psi-monitor: Add options to adjust monitoring parameters #401

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84 changes: 69 additions & 15 deletions psi-monitor/psi-monitor.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,23 +4,29 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>

/* Daemon parameters */
#define POLL_INTERVAL 5
#define RECOVERY_INTERVAL 15
#define MEM_THRESHOLD 10
static unsigned int poll_interval = 5;
static unsigned int recovery_interval = 15;
static unsigned int mem_threshold = 10;

#define SYSRQ_TRIGGER_FILE "/proc/sysrq-trigger"
#define PSI_MEMORY_FILE "/proc/pressure/memory"
#define BUFSIZE 256

static bool opt_debug = false;
static const char *short_options = "dh";
static const char *short_options = "m:p:r:dh";
static struct option long_options[] = {
{"mem-threshold", 1, 0, 'm'},
{"poll-interval", 1, 0, 'p'},
{"recovery-interval", 1, 0, 'r'},
{"debug", 0, 0, 'd'},
{"help", 0, 0, 'h'},
{0, 0, 0, 0}
Expand All @@ -30,9 +36,48 @@ static void usage(const char *progname) {
printf("Usage: %s [OPTION]...\n"
"Invoke out of memory killer on excessive memory pressure.\n"
"\n"
" -d, --debug\tprint debugging messages\n"
" -h, --help\tdisplay this help and exit\n",
progname);
" -m, --mem-threshold PCT\tmemory threshold percentage (default: %u)\n"
" -p, --poll-interval SEC\tpoll interval seconds (default: %u)\n"
" -r, --recovery-interval SEC\trecovery interval seconds (default: %u)\n"
" -d, --debug\t\t\tprint debugging messages\n"
" -h, --help\t\t\tdisplay this help and exit\n",
progname, mem_threshold, poll_interval, recovery_interval);
}

static void set_mem_threshold(const char *arg) {
long val;
char *endptr = NULL;

errno = 0;
val = strtol(arg, &endptr, 10);
if (errno != 0)
err(1, "Invalid memory threshold value \"%s\"", arg);
if (endptr == arg)
errx(1, "No memory threshold value provided");
if (val < 0)
errx(1, "Memory threshold value cannot be negative");
if (val > 100)
errx(1, "Memory threshold value cannot exceed 100");
mem_threshold = (unsigned int) val;
}

static void set_interval(unsigned int *var, const char *arg) {
long val;
char *endptr = NULL;

assert(var != NULL);

errno = 0;
val = strtol(arg, &endptr, 10);
if (errno != 0)
err(1, "Invalid interval value \"%s\"", arg);
if (endptr == arg)
errx(1, "No interval value provided");
if (val < 0)
errx(1, "Interval value cannot be negative");
if (val > UINT_MAX)
errx(1, "Interval value cannot exceed %u", UINT_MAX);
*var = (unsigned int) val;
}

static ssize_t fstr(const char *path, char *rbuf, const char *wbuf) {
Expand Down Expand Up @@ -63,7 +108,7 @@ static ssize_t fstr(const char *path, char *rbuf, const char *wbuf) {

static void sysrq_trigger_oom() {
fstr(SYSRQ_TRIGGER_FILE, NULL, "f");
sleep(RECOVERY_INTERVAL);
sleep(recovery_interval);
}

int main(int argc, char **argv) {
Expand All @@ -73,6 +118,15 @@ int main(int argc, char **argv) {
break;

switch (c) {
case 'm':
set_mem_threshold(optarg);
break;
case 'p':
set_interval(&poll_interval, optarg);
break;
case 'r':
set_interval(&recovery_interval, optarg);
break;
case 'd':
opt_debug = true;
break;
Expand All @@ -85,8 +139,8 @@ int main(int argc, char **argv) {
}

setvbuf(stdout, NULL, _IOLBF, 0);
printf("poll_interval=%ds, recovery_interval=%ds, stall_threshold=%d%%\n",
POLL_INTERVAL, RECOVERY_INTERVAL, MEM_THRESHOLD);
printf("poll_interval=%us, recovery_interval=%us, mem_threshold=%u%%\n",
poll_interval, recovery_interval, mem_threshold);

while (true) {
int i;
Expand All @@ -102,13 +156,13 @@ int main(int argc, char **argv) {
sscanf(buf+i, "%f", &full_avg10);
if (opt_debug) printf("full_avg10=%f\n", full_avg10);

if (full_avg10 > MEM_THRESHOLD) {
printf("Memory pressure %.1f%% above threshold limit %d%%, "
"killing task and pausing %d seconds for recovery\n",
full_avg10, MEM_THRESHOLD, RECOVERY_INTERVAL);
if (full_avg10 > mem_threshold) {
printf("Memory pressure %.1f%% above threshold limit %u%%, "
"killing task and pausing %u seconds for recovery\n",
full_avg10, mem_threshold, recovery_interval);
sysrq_trigger_oom();
} else {
sleep(POLL_INTERVAL);
sleep(poll_interval);
}
}

Expand Down