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free: add 'available' memory if provided by the kernel

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Show estimated available memory if this is provided by the
kernel. See [1] for the full story.

 [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=34e431b0ae398fc54ea69ff85ec700722c9da773

function                                             old     new   delta
free_main                                            537     633     +96
parse_cached_kb                                       85       -     -85
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/0 up/down: 96/-85)             Total: 11 bytes

Signed-off-by: Guillermo Rodriguez <guille.rodriguez@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Guillermo Rodriguez 2018-10-30 13:49:51 +01:00 committed by Denys Vlasenko
parent 47839ae679
commit c8e3922ad8
1 changed files with 36 additions and 23 deletions
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59
procps/free.c
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@ -53,21 +53,27 @@ static unsigned long long scale(struct globals *g, unsigned long d)
} }
/* NOINLINE reduces main() stack usage, which makes code smaller (on x86 at least) */ /* NOINLINE reduces main() stack usage, which makes code smaller (on x86 at least) */
static NOINLINE unsigned long parse_cached_kb(void) static NOINLINE unsigned int parse_meminfo(unsigned long *cached_kb, unsigned long *available_kb)
{ {
char buf[60]; /* actual lines we expect are ~30 chars or less */ char buf[60]; /* actual lines we expect are ~30 chars or less */
FILE *fp; FILE *fp;
unsigned long cached = 0; int seen_cached_and_available;
fp = xfopen_for_read("/proc/meminfo"); fp = xfopen_for_read("/proc/meminfo");
while (fgets(buf, sizeof(buf), fp) != NULL) { *cached_kb = *available_kb = 0;
if (sscanf(buf, "Cached: %lu %*s\n", &cached) == 1) seen_cached_and_available = 2;
break; while (fgets(buf, sizeof(buf), fp)) {
if (sscanf(buf, "Cached: %lu %*s\n", cached_kb) == 1)
if (--seen_cached_and_available == 0)
break;
if (sscanf(buf, "MemAvailable: %lu %*s\n", available_kb) == 1)
if (--seen_cached_and_available == 0)
break;
} }
/* Have to close because of NOFORK */ /* Have to close because of NOFORK */
fclose(fp); fclose(fp);
return cached; return seen_cached_and_available == 0;
} }
int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@ -75,7 +81,9 @@ int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
{ {
struct globals G; struct globals G;
struct sysinfo info; struct sysinfo info;
unsigned long long cached; unsigned long long cached, cached_plus_free, available;
unsigned long cached_kb, available_kb;
int seen_available;
#if ENABLE_DESKTOP #if ENABLE_DESKTOP
G.unit_steps = 10; G.unit_steps = 10;
@ -98,41 +106,46 @@ int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
} }
} }
#endif #endif
printf(" %11s%11s%11s%11s%11s%11s\n" printf(" %12s%12s%12s%12s%12s%12s\n"
"Mem: ", "Mem: ",
"total", "total",
"used", "used",
"free", "free",
"shared", "buffers", "cached" /* swap and total don't have these columns */ "shared", "buff/cache", "available" /* swap and total don't have these columns */
); );
sysinfo(&info); sysinfo(&info);
/* Kernels prior to 2.4.x will return info.mem_unit==0, so cope... */ /* Kernels prior to 2.4.x will return info.mem_unit==0, so cope... */
G.mem_unit = (info.mem_unit ? info.mem_unit : 1); G.mem_unit = (info.mem_unit ? info.mem_unit : 1);
/* Extract cached from /proc/meminfo and convert to mem_units */ /* Extract cached and memavailable from /proc/meminfo and convert to mem_units */
cached = ((unsigned long long) parse_cached_kb() * 1024) / G.mem_unit; seen_available = parse_meminfo(&cached_kb, &available_kb);
available = ((unsigned long long) available_kb * 1024) / G.mem_unit;
cached = ((unsigned long long) cached_kb * 1024) / G.mem_unit;
cached += info.bufferram;
cached_plus_free = cached + info.freeram;
#define FIELDS_6 "%11llu%11llu%11llu%11llu%11llu%11llu\n" #define FIELDS_6 "%12llu%12llu%12llu%12llu%12llu%12llu\n"
#define FIELDS_3 (FIELDS_6 + 3*6) #define FIELDS_3 (FIELDS_6 + 3*6)
#define FIELDS_2 (FIELDS_6 + 4*6) #define FIELDS_2 (FIELDS_6 + 4*6)
printf(FIELDS_6, printf(FIELDS_6,
scale(&G, info.totalram), //total scale(&G, info.totalram), //total
scale(&G, info.totalram - info.freeram), //used scale(&G, info.totalram - cached_plus_free), //used
scale(&G, info.freeram), //free scale(&G, info.freeram), //free
scale(&G, info.sharedram), //shared scale(&G, info.sharedram), //shared
scale(&G, info.bufferram), //buffers scale(&G, cached), //buff/cache
scale(&G, cached) //cached scale(&G, available) //available
); );
/* Show alternate, more meaningful busy/free numbers by counting /* On kernels < 3.14, MemAvailable is not provided.
* Show alternate, more meaningful busy/free numbers by counting
* buffer cache as free memory. */ * buffer cache as free memory. */
printf("-/+ buffers/cache:"); if (!seen_available) {
cached += info.freeram; printf("-/+ buffers/cache: ");
cached += info.bufferram; printf(FIELDS_2,
printf(FIELDS_2, scale(&G, info.totalram - cached_plus_free), //used
scale(&G, info.totalram - cached), //used scale(&G, cached_plus_free) //free
scale(&G, cached) //free );
); }
#if BB_MMU #if BB_MMU
printf("Swap: "); printf("Swap: ");
printf(FIELDS_3, printf(FIELDS_3,