1 files changed, 49 insertions, 1 deletions
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 0f2ca4b15..48df839fa 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -11,6 +11,11 @@
 #include <dlfcn.h>
 #include <sys/utsname.h>
 
+#if __linux__
+#include <mntent.h>
+#include <cmath>
+#endif
+
 #include <nlohmann/json.hpp>
 
 
@@ -114,7 +119,50 @@ std::vector<Path> getUserConfigFiles()
 
 unsigned int Settings::getDefaultCores()
 {
-    return std::max(1U, std::thread::hardware_concurrency());
+    unsigned int concurrency = std::max(1U, std::thread::hardware_concurrency());
+
+    #if __linux__
+    FILE *fp = fopen("/proc/mounts", "r");
+    if (!fp)
+        return concurrency;
+
+    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")
+                concurrency = std::ceil(std::stoi(quota) / std::stof(period));
+        }
+    }
+    #endif
+
+    return concurrency;
 }
 
 StringSet Settings::getDefaultSystemFeatures()