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more concise memory calculation on Linux

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more flexible parsing for /proc/meminfo to take shared and reclaimable
memory into account. this matches the output with free(1).

additionally this could fix some corner cases, as the order of fields in
/proc/meminfo is not strictly defined.

slstatus:
percent 81% free 2.5 Gi total 23.4 Gi used 19.0 Gi

free(1):
               total        used        free      shared  buff/cache   available
Mem:            23Gi        19Gi       2.5Gi       1.3Gi       3.2Gi       3.6Gi
This commit is contained in:
drkhsh 2025-07-24 22:41:25 +02:00
parent 6eb7887853
commit 8723e8b8c6
3 changed files with 57 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
components/ram.c
View File

@ -11,36 +11,45 @@
ram_free(const char *unused)
{
uintmax_t free;
FILE *fp;
if (pscanf("/proc/meminfo",
"MemTotal: %ju kB\n"
"MemFree: %ju kB\n"
"MemAvailable: %ju kB\n",
&free, &free, &free) != 3)
if (!(fp = fopen("/proc/meminfo", "r")))
return NULL;
if (lscanf(fp, "MemFree:", "%ju kB", &free) != 1) {
fclose(fp);
return NULL;
}
fclose(fp);
return fmt_human(free * 1024, 1024);
}
const char *
ram_perc(const char *unused)
{
uintmax_t total, free, buffers, cached;
uintmax_t total, free, buffers, cached, shmem, sreclaimable;
int percent;
FILE *fp;
if (pscanf("/proc/meminfo",
"MemTotal: %ju kB\n"
"MemFree: %ju kB\n"
"MemAvailable: %ju kB\n"
"Buffers: %ju kB\n"
"Cached: %ju kB\n",
&total, &free, &buffers, &buffers, &cached) != 5)
if (!(fp = fopen("/proc/meminfo", "r")))
return NULL;
if (lscanf(fp, "MemTotal:", "%ju kB", &total) != 1 ||
lscanf(fp, "MemFree:", "%ju kB", &free) != 1 ||
lscanf(fp, "Buffers:", "%ju kB", &buffers) != 1 ||
lscanf(fp, "Cached:", "%ju kB", &cached) != 1 ||
lscanf(fp, "Shmem:", "%ju kB", &shmem) != 1 ||
lscanf(fp, "SReclaimable:", "%ju kB", &sreclaimable) != 1) {
fclose(fp);
return NULL;
}
fclose(fp);
if (total == 0)
return NULL;
percent = 100 * ((total - free) - (buffers + cached)) / total;
percent = 100 * (total - free - buffers - cached - sreclaimable + shmem) / total;
return bprintf("%d", percent);
}
@ -59,18 +68,24 @@
const char *
ram_used(const char *unused)
{
uintmax_t total, free, buffers, cached, used;
uintmax_t total, free, buffers, cached, used, shmem, sreclaimable;
FILE *fp;
if (pscanf("/proc/meminfo",
"MemTotal: %ju kB\n"
"MemFree: %ju kB\n"
"MemAvailable: %ju kB\n"
"Buffers: %ju kB\n"
"Cached: %ju kB\n",
&total, &free, &buffers, &buffers, &cached) != 5)
if (!(fp = fopen("/proc/meminfo", "r")))
return NULL;
used = (total - free - buffers - cached);
if (lscanf(fp, "MemTotal:", "%ju kB", &total) != 1 ||
lscanf(fp, "MemFree:", "%ju kB", &free) != 1 ||
lscanf(fp, "Buffers:", "%ju kB", &buffers) != 1 ||
lscanf(fp, "Cached:", "%ju kB", &cached) != 1 ||
lscanf(fp, "Shmem:", "%ju kB", &shmem) != 1 ||
lscanf(fp, "SReclaimable:", "%ju kB", &sreclaimable) != 1) {
fclose(fp);
return NULL;
}
fclose(fp);
used = total - free - buffers - cached - sreclaimable + shmem;
return fmt_human(used * 1024, 1024);
}
#elif defined(__OpenBSD__)

17
util.c
View File

@ -139,3 +139,20 @@ pscanf(const char *path, const char *fmt, ...)
return (n == EOF) ? -1 : n;
}
int
lscanf(FILE *fp, const char *key, const char *fmt, void *res)
{
int n;
char line[256];
n = -1;
while (fgets(line, sizeof(line), fp))
if (strncmp(line, key, strlen(key)) == 0) {
n = sscanf(line + strlen(key), fmt, res);
break;
}
rewind(fp);
return (n == 1) ? 1 : -1;
}

2
util.h
View File

@ -1,5 +1,6 @@
/* See LICENSE file for copyright and license details. */
#include <stdint.h>
#include <stdio.h>
extern char buf[1024];
@ -14,3 +15,4 @@ int esnprintf(char *str, size_t size, const char *fmt, ...);
const char *bprintf(const char *fmt, ...);
const char *fmt_human(uintmax_t num, int base);
int pscanf(const char *path, const char *fmt, ...);
int lscanf(FILE *fp, const char *key, const char *fmt, void *res);