sysinfo: use bits.OnesCount64, drop popcnt

Slightly less code to maintain.

Signed-off-by: Kir Kolyshkin <[email protected]>

Author: kolyshkin

Diff for: pkg/sysinfo/numcpu_windows.go

@@ -3,6 +3,7 @@
 package sysinfo
 
 import (
+	"math/bits"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
@@ -22,7 +23,5 @@ func numCPU() int {
 	if ret == 0 {
 		return 0
 	}
-	// For every available thread a bit is set in the mask.
-	ncpu := int(popcnt(uint64(mask)))
-	return ncpu
+	return bits.OnesCount64(uint64(mask))
 }

Diff for: pkg/sysinfo/sysinfo.go

@@ -133,16 +133,6 @@ func isCpusetListAvailable(provided, available string) (bool, error) {
 	return true, nil
 }
 
-// Returns bit count of 1, used by NumCPU
-func popcnt(x uint64) (n byte) {
-	x -= (x >> 1) & 0x5555555555555555
-	x = (x>>2)&0x3333333333333333 + x&0x3333333333333333
-	x += x >> 4
-	x &= 0x0f0f0f0f0f0f0f0f
-	x *= 0x0101010101010101
-	return byte(x >> 56)
-}
-
 // GetDefaultPidsLimit returns the default pids limit to run containers with
 func GetDefaultPidsLimit() int64 {
 	sysInfo := New(true)