77 lines
1.4 KiB
Go
77 lines
1.4 KiB
Go
package platform
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import (
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"math/bits"
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"os"
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"sort"
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"strconv"
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"strings"
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"syscall"
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)
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const (
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// https://man7.org/linux/man-pages/man2/mmap.2.html
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__MAP_HUGE_SHIFT = 26
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__MAP_HUGETLB = 0x40000
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)
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var hugePagesConfigs []hugePagesConfig
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type hugePagesConfig struct {
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size int
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flag int
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}
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func (hpc *hugePagesConfig) match(size int) bool {
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return (size & (hpc.size - 1)) == 0
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}
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func init() {
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dirents, err := os.ReadDir("/sys/kernel/mm/hugepages/")
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if err != nil {
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return
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}
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for _, dirent := range dirents {
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name := dirent.Name()
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if !strings.HasPrefix(name, "hugepages-") {
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continue
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}
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if !strings.HasSuffix(name, "kB") {
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continue
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}
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n, err := strconv.ParseUint(name[10:len(name)-2], 10, 64)
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if err != nil {
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continue
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}
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if bits.OnesCount64(n) != 1 {
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continue
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}
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n *= 1024
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hugePagesConfigs = append(hugePagesConfigs, hugePagesConfig{
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size: int(n),
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flag: int(bits.TrailingZeros64(n)<<__MAP_HUGE_SHIFT) | __MAP_HUGETLB,
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})
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}
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sort.Slice(hugePagesConfigs, func(i, j int) bool {
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return hugePagesConfigs[i].size > hugePagesConfigs[j].size
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})
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}
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func mmapCodeSegment(size, prot int) ([]byte, error) {
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flags := syscall.MAP_ANON | syscall.MAP_PRIVATE
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for _, hugePagesConfig := range hugePagesConfigs {
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if hugePagesConfig.match(size) {
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b, err := syscall.Mmap(-1, 0, size, prot, flags|hugePagesConfig.flag)
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if err != nil {
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continue
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}
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return b, nil
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}
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}
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return syscall.Mmap(-1, 0, size, prot, flags)
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}
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