Merge pull request #6813 from centromere/cgroup-cpu-detection

libstore/globals.cc: Automatically set cores based on cgroup CPU limit
This commit is contained in:
Théophane Hufschmitt 2022-07-22 10:15:32 +02:00 committed by GitHub
commit e10807cdbb
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3 changed files with 61 additions and 1 deletions

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@ -114,7 +114,13 @@ std::vector<Path> getUserConfigFiles()
unsigned int Settings::getDefaultCores() unsigned int Settings::getDefaultCores()
{ {
return std::max(1U, std::thread::hardware_concurrency()); const unsigned int concurrency = std::max(1U, std::thread::hardware_concurrency());
const unsigned int maxCPU = getMaxCPU();
if (maxCPU > 0)
return maxCPU;
else
return concurrency;
} }
StringSet Settings::getDefaultSystemFeatures() StringSet Settings::getDefaultSystemFeatures()

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@ -35,6 +35,9 @@
#ifdef __linux__ #ifdef __linux__
#include <sys/prctl.h> #include <sys/prctl.h>
#include <sys/resource.h> #include <sys/resource.h>
#include <mntent.h>
#include <cmath>
#endif #endif
@ -788,7 +791,55 @@ void drainFD(int fd, Sink & sink, bool block)
} }
} }
//////////////////////////////////////////////////////////////////////
unsigned int getMaxCPU()
{
#if __linux__
try {
FILE *fp = fopen("/proc/mounts", "r");
if (!fp)
return 0;
Strings cgPathParts;
struct mntent *ent;
while ((ent = getmntent(fp))) {
std::string mountType, mountPath;
mountType = ent->mnt_type;
mountPath = ent->mnt_dir;
if (mountType == "cgroup2") {
cgPathParts.push_back(mountPath);
break;
}
}
fclose(fp);
if (cgPathParts.size() > 0 && pathExists("/proc/self/cgroup")) {
std::string currentCgroup = readFile("/proc/self/cgroup");
Strings cgValues = tokenizeString<Strings>(currentCgroup, ":");
cgPathParts.push_back(trim(cgValues.back(), "\n"));
cgPathParts.push_back("cpu.max");
std::string fullCgPath = canonPath(concatStringsSep("/", cgPathParts));
if (pathExists(fullCgPath)) {
std::string cpuMax = readFile(fullCgPath);
std::vector<std::string> cpuMaxParts = tokenizeString<std::vector<std::string>>(cpuMax, " ");
std::string quota = cpuMaxParts[0];
std::string period = trim(cpuMaxParts[1], "\n");
if (quota != "max")
return std::ceil(std::stoi(quota) / std::stof(period));
}
}
} catch (Error &) { ignoreException(); }
#endif
return 0;
}
////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////

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@ -182,6 +182,9 @@ std::string drainFD(int fd, bool block = true, const size_t reserveSize=0);
void drainFD(int fd, Sink & sink, bool block = true); void drainFD(int fd, Sink & sink, bool block = true);
/* If cgroups are active, attempt to calculate the number of CPUs available.
If cgroups are unavailable or if cpu.max is set to "max", return 0. */
unsigned int getMaxCPU();
/* Automatic cleanup of resources. */ /* Automatic cleanup of resources. */