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moby--moby/pkg/sysinfo/numcpu_windows.go
Tobias Klauser ba8a15694a Use functions from x/sys/unix to get number of CPUs on Linux
Use Getpid and SchedGetaffinity from golang.org/x/sys/unix to get the
number of CPUs in numCPU on Linux.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2019-06-18 19:26:56 +02:00

45 lines
1.1 KiB
Go

package sysinfo // import "github.com/docker/docker/pkg/sysinfo"
import (
"runtime"
"unsafe"
"golang.org/x/sys/windows"
)
var (
kernel32 = windows.NewLazySystemDLL("kernel32.dll")
getCurrentProcess = kernel32.NewProc("GetCurrentProcess")
getProcessAffinityMask = kernel32.NewProc("GetProcessAffinityMask")
)
// 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)
}
func numCPU() int {
// Gets the affinity mask for a process
var mask, sysmask uintptr
currentProcess, _, _ := getCurrentProcess.Call()
ret, _, _ := getProcessAffinityMask.Call(currentProcess, uintptr(unsafe.Pointer(&mask)), uintptr(unsafe.Pointer(&sysmask)))
if ret == 0 {
return 0
}
// For every available thread a bit is set in the mask.
ncpu := int(popcnt(uint64(mask)))
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()
}