1 files changed, 44 insertions, 0 deletions
diff --git a/pkg/sysinfo/numcpu_linux.go b/pkg/sysinfo/numcpu_linux.go
new file mode 100644
index 000000000..f1d2d9db3
--- /dev/null
+++ b/pkg/sysinfo/numcpu_linux.go
@@ -0,0 +1,44 @@
+// +build linux
+
+package sysinfo
+
+import (
+	"runtime"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// numCPU queries the system for the count of threads available
+// for use to this process.
+//
+// Issues two syscalls.
+// Returns 0 on errors. Use |runtime.NumCPU| in that case.
+func numCPU() int {
+	// Gets the affinity mask for a process: The very one invoking this function.
+	pid, _, _ := unix.RawSyscall(unix.SYS_GETPID, 0, 0, 0)
+
+	var mask [1024 / 64]uintptr
+	_, _, err := unix.RawSyscall(unix.SYS_SCHED_GETAFFINITY, pid, uintptr(len(mask)*8), uintptr(unsafe.Pointer(&mask[0])))
+	if err != 0 {
+		return 0
+	}
+
+	// For every available thread a bit is set in the mask.
+	ncpu := 0
+	for _, e := range mask {
+		if e == 0 {
+			continue
+		}
+		ncpu += int(popcnt(uint64(e)))
+	}
+	return ncpu
+}
+
+// NumCPU returns the number of CPUs which are currently online
+func NumCPU() int {
+	if ncpu := numCPU(); ncpu > 0 {
+		return ncpu
+	}
+	return runtime.NumCPU()
+}