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ba8a15694a
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>
45 lines
1.1 KiB
Go
45 lines
1.1 KiB
Go
package sysinfo // import "github.com/docker/docker/pkg/sysinfo"
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import (
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"runtime"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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var (
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kernel32 = windows.NewLazySystemDLL("kernel32.dll")
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getCurrentProcess = kernel32.NewProc("GetCurrentProcess")
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getProcessAffinityMask = kernel32.NewProc("GetProcessAffinityMask")
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)
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// Returns bit count of 1, used by NumCPU
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func popcnt(x uint64) (n byte) {
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x -= (x >> 1) & 0x5555555555555555
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x = (x>>2)&0x3333333333333333 + x&0x3333333333333333
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x += x >> 4
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x &= 0x0f0f0f0f0f0f0f0f
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x *= 0x0101010101010101
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return byte(x >> 56)
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}
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func numCPU() int {
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// Gets the affinity mask for a process
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var mask, sysmask uintptr
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currentProcess, _, _ := getCurrentProcess.Call()
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ret, _, _ := getProcessAffinityMask.Call(currentProcess, uintptr(unsafe.Pointer(&mask)), uintptr(unsafe.Pointer(&sysmask)))
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if ret == 0 {
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return 0
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}
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// For every available thread a bit is set in the mask.
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ncpu := int(popcnt(uint64(mask)))
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return ncpu
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}
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// NumCPU returns the number of CPUs which are currently online
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func NumCPU() int {
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if ncpu := numCPU(); ncpu > 0 {
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return ncpu
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}
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return runtime.NumCPU()
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}
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