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author | Péter Szilágyi <peterke@gmail.com> | 2019-02-15 00:14:28 +0800 |
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committer | Péter Szilágyi <peterke@gmail.com> | 2019-02-19 16:59:24 +0800 |
commit | d9be33766930b6978629a02643a8c83265a3006b (patch) | |
tree | 1245792f4e7bf63374148586f8c4ee612796a299 /vendor/golang.org/x/sys/unix/affinity_linux.go | |
parent | 7bd6f39dc3eb174d5869613bc24f431ec96dabff (diff) | |
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vendor: update syscalls dependency
(cherry picked from commit dcc045f03c7c933dcdc7302f0338cbbfef7398ea)
Diffstat (limited to 'vendor/golang.org/x/sys/unix/affinity_linux.go')
-rw-r--r-- | vendor/golang.org/x/sys/unix/affinity_linux.go | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/vendor/golang.org/x/sys/unix/affinity_linux.go b/vendor/golang.org/x/sys/unix/affinity_linux.go new file mode 100644 index 000000000..72afe3338 --- /dev/null +++ b/vendor/golang.org/x/sys/unix/affinity_linux.go @@ -0,0 +1,124 @@ +// Copyright 2018 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// CPU affinity functions + +package unix + +import ( + "unsafe" +) + +const cpuSetSize = _CPU_SETSIZE / _NCPUBITS + +// CPUSet represents a CPU affinity mask. +type CPUSet [cpuSetSize]cpuMask + +func schedAffinity(trap uintptr, pid int, set *CPUSet) error { + _, _, e := RawSyscall(trap, uintptr(pid), uintptr(unsafe.Sizeof(*set)), uintptr(unsafe.Pointer(set))) + if e != 0 { + return errnoErr(e) + } + return nil +} + +// SchedGetaffinity gets the CPU affinity mask of the thread specified by pid. +// If pid is 0 the calling thread is used. +func SchedGetaffinity(pid int, set *CPUSet) error { + return schedAffinity(SYS_SCHED_GETAFFINITY, pid, set) +} + +// SchedSetaffinity sets the CPU affinity mask of the thread specified by pid. +// If pid is 0 the calling thread is used. +func SchedSetaffinity(pid int, set *CPUSet) error { + return schedAffinity(SYS_SCHED_SETAFFINITY, pid, set) +} + +// Zero clears the set s, so that it contains no CPUs. +func (s *CPUSet) Zero() { + for i := range s { + s[i] = 0 + } +} + +func cpuBitsIndex(cpu int) int { + return cpu / _NCPUBITS +} + +func cpuBitsMask(cpu int) cpuMask { + return cpuMask(1 << (uint(cpu) % _NCPUBITS)) +} + +// Set adds cpu to the set s. +func (s *CPUSet) Set(cpu int) { + i := cpuBitsIndex(cpu) + if i < len(s) { + s[i] |= cpuBitsMask(cpu) + } +} + +// Clear removes cpu from the set s. +func (s *CPUSet) Clear(cpu int) { + i := cpuBitsIndex(cpu) + if i < len(s) { + s[i] &^= cpuBitsMask(cpu) + } +} + +// IsSet reports whether cpu is in the set s. +func (s *CPUSet) IsSet(cpu int) bool { + i := cpuBitsIndex(cpu) + if i < len(s) { + return s[i]&cpuBitsMask(cpu) != 0 + } + return false +} + +// Count returns the number of CPUs in the set s. +func (s *CPUSet) Count() int { + c := 0 + for _, b := range s { + c += onesCount64(uint64(b)) + } + return c +} + +// onesCount64 is a copy of Go 1.9's math/bits.OnesCount64. +// Once this package can require Go 1.9, we can delete this +// and update the caller to use bits.OnesCount64. +func onesCount64(x uint64) int { + const m0 = 0x5555555555555555 // 01010101 ... + const m1 = 0x3333333333333333 // 00110011 ... + const m2 = 0x0f0f0f0f0f0f0f0f // 00001111 ... + const m3 = 0x00ff00ff00ff00ff // etc. + const m4 = 0x0000ffff0000ffff + + // Implementation: Parallel summing of adjacent bits. + // See "Hacker's Delight", Chap. 5: Counting Bits. + // The following pattern shows the general approach: + // + // x = x>>1&(m0&m) + x&(m0&m) + // x = x>>2&(m1&m) + x&(m1&m) + // x = x>>4&(m2&m) + x&(m2&m) + // x = x>>8&(m3&m) + x&(m3&m) + // x = x>>16&(m4&m) + x&(m4&m) + // x = x>>32&(m5&m) + x&(m5&m) + // return int(x) + // + // Masking (& operations) can be left away when there's no + // danger that a field's sum will carry over into the next + // field: Since the result cannot be > 64, 8 bits is enough + // and we can ignore the masks for the shifts by 8 and up. + // Per "Hacker's Delight", the first line can be simplified + // more, but it saves at best one instruction, so we leave + // it alone for clarity. + const m = 1<<64 - 1 + x = x>>1&(m0&m) + x&(m0&m) + x = x>>2&(m1&m) + x&(m1&m) + x = (x>>4 + x) & (m2 & m) + x += x >> 8 + x += x >> 16 + x += x >> 32 + return int(x) & (1<<7 - 1) +} |