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linux: teach uv_get_constrained_memory() cgroupsv2 (#3744)

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Fixes: https://github.com/libuv/libuv/issues/2315
This commit is contained in:
Ben Noordhuis 2022-09-15 08:56:56 +02:00 committed by GitHub
parent 0f478a7de7
commit d59b2905f9
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 44 additions and 10 deletions
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54
src/unix/linux-core.c
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@ -793,27 +793,61 @@ uint64_t uv_get_total_memory(void) {
}
static uint64_t uv__read_cgroups_uint64(const char* cgroup, const char* param) {
char filename[256];
static uint64_t uv__read_uint64(const char* filename) {
char buf[32]; /* Large enough to hold an encoded uint64_t. */
uint64_t rc;
rc = 0;
snprintf(filename, sizeof(filename), "/sys/fs/cgroup/%s/%s", cgroup, param);
if (0 == uv__slurp(filename, buf, sizeof(buf)))
sscanf(buf, "%" PRIu64, &rc);
if (1 != sscanf(buf, "%" PRIu64, &rc))
if (0 == strcmp(buf, "max\n"))
rc = ~0ull;
return rc;
}
/* This might return 0 if there was a problem getting the memory limit from
* cgroups. This is OK because a return value of 0 signifies that the memory
* limit is unknown.
*/
static uint64_t uv__get_constrained_memory_fallback(void) {
return uv__read_uint64("/sys/fs/cgroup/memory/memory.limit_in_bytes");
}
uint64_t uv_get_constrained_memory(void) {
/*
* This might return 0 if there was a problem getting the memory limit from
* cgroups. This is OK because a return value of 0 signifies that the memory
* limit is unknown.
*/
return uv__read_cgroups_uint64("memory", "memory.limit_in_bytes");
char filename[4097];
char buf[1024];
uint64_t high;
uint64_t max;
char* p;
if (uv__slurp("/proc/self/cgroup", buf, sizeof(buf)))
return uv__get_constrained_memory_fallback();
if (memcmp(buf, "0::/", 4))
return uv__get_constrained_memory_fallback();
p = strchr(buf, '\n');
if (p != NULL)
*p = '\0';
p = buf + 4;
snprintf(filename, sizeof(filename), "/sys/fs/cgroup/%s/memory.max", p);
max = uv__read_uint64(filename);
if (max == 0)
return uv__get_constrained_memory_fallback();
snprintf(filename, sizeof(filename), "/sys/fs/cgroup/%s/memory.high", p);
high = uv__read_uint64(filename);
if (high == 0)
return uv__get_constrained_memory_fallback();
return high < max ? high : max;
}