From c55eeeb718b0dfd008f0d722c8b8d05f8b02d62b Mon Sep 17 00:00:00 2001 From: Tobias Klauser Date: Fri, 8 Feb 2019 09:25:05 +0100 Subject: [PATCH] runtime: use hw.ncpuonline sysctl in getncpu on openbsd The number of CPUs reported by the hw.ncpu sysctl is twice as high as the actual number of CPUs running on OpenBSD 6.4. with hyperthreading disabled (hw.smt=0). Try hw.cpuonline first and fall back to hw.ncpu in case it fails (which is the case on older OpenBSD before 6.4). Fixes #30127 Change-Id: Id091234b8038cc9f7c40519d039fc1a05437c40d Reviewed-on: https://go-review.googlesource.com/c/161757 Run-TryBot: Tobias Klauser TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick Reviewed-by: Matthew Dempsky --- src/runtime/os_openbsd.go | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/src/runtime/os_openbsd.go b/src/runtime/os_openbsd.go index 96112cb25b..353a5d94ba 100644 --- a/src/runtime/os_openbsd.go +++ b/src/runtime/os_openbsd.go @@ -84,9 +84,10 @@ const ( _CTL_KERN = 1 _KERN_OSREV = 3 - _CTL_HW = 6 - _HW_NCPU = 3 - _HW_PAGESIZE = 7 + _CTL_HW = 6 + _HW_NCPU = 3 + _HW_PAGESIZE = 7 + _HW_NCPUONLINE = 25 ) func sysctlInt(mib []uint32) (int32, bool) { @@ -100,9 +101,14 @@ func sysctlInt(mib []uint32) (int32, bool) { } func getncpu() int32 { - // Fetch hw.ncpu via sysctl. - if ncpu, ok := sysctlInt([]uint32{_CTL_HW, _HW_NCPU}); ok { - return int32(ncpu) + // Try hw.ncpuonline first because hw.ncpu would report a number twice as + // high as the actual CPUs running on OpenBSD 6.4 with hyperthreading + // disabled (hw.smt=0). See https://golang.org/issue/30127 + if n, ok := sysctlInt([]uint32{_CTL_HW, _HW_NCPUONLINE}); ok { + return int32(n) + } + if n, ok := sysctlInt([]uint32{_CTL_HW, _HW_NCPU}); ok { + return int32(n) } return 1 }