1 files changed, 132 insertions, 0 deletions
diff --git a/src/runtime/os_illumos.go b/src/runtime/os_illumos.go
new file mode 100644
index 0000000..c3c3e4e
--- /dev/null
+++ b/src/runtime/os_illumos.go
@@ -0,0 +1,132 @@
+// Copyright 2019 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.
+
+package runtime
+
+import (
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_getrctl getrctl "libc.so"
+//go:cgo_import_dynamic libc_rctlblk_get_local_action rctlblk_get_local_action "libc.so"
+//go:cgo_import_dynamic libc_rctlblk_get_local_flags rctlblk_get_local_flags "libc.so"
+//go:cgo_import_dynamic libc_rctlblk_get_value rctlblk_get_value "libc.so"
+//go:cgo_import_dynamic libc_rctlblk_size rctlblk_size "libc.so"
+
+//go:linkname libc_getrctl libc_getrctl
+//go:linkname libc_rctlblk_get_local_action libc_rctlblk_get_local_action
+//go:linkname libc_rctlblk_get_local_flags libc_rctlblk_get_local_flags
+//go:linkname libc_rctlblk_get_value libc_rctlblk_get_value
+//go:linkname libc_rctlblk_size libc_rctlblk_size
+
+var (
+	libc_getrctl,
+	libc_rctlblk_get_local_action,
+	libc_rctlblk_get_local_flags,
+	libc_rctlblk_get_value,
+	libc_rctlblk_size libcFunc
+)
+
+// Return the minimum value seen for the zone CPU cap, or 0 if no cap is
+// detected.
+func getcpucap() uint64 {
+	// The resource control block is an opaque object whose size is only
+	// known to libc.  In practice, given the contents, it is unlikely to
+	// grow beyond 8KB so we'll use a static buffer of that size here.
+	const rblkmaxsize = 8 * 1024
+	if rctlblk_size() > rblkmaxsize {
+		return 0
+	}
+
+	// The "zone.cpu-cap" resource control, as described in
+	// resource_controls(5), "sets a limit on the amount of CPU time that
+	// can be used by a zone.  The unit used is the percentage of a single
+	// CPU that can be used by all user threads in a zone, expressed as an
+	// integer."  A C string of the name must be passed to getrctl(2).
+	name := []byte("zone.cpu-cap\x00")
+
+	// To iterate over the list of values for a particular resource
+	// control, we need two blocks: one for the previously read value and
+	// one for the next value.
+	var rblk0 [rblkmaxsize]byte
+	var rblk1 [rblkmaxsize]byte
+	rblk := &rblk0[0]
+	rblkprev := &rblk1[0]
+
+	var flag uint32 = _RCTL_FIRST
+	var capval uint64 = 0
+
+	for {
+		if getrctl(unsafe.Pointer(&name[0]), unsafe.Pointer(rblkprev), unsafe.Pointer(rblk), flag) != 0 {
+			// The end of the sequence is reported as an ENOENT
+			// failure, but determining the CPU cap is not critical
+			// here.  We'll treat any failure as if it were the end
+			// of sequence.
+			break
+		}
+
+		lflags := rctlblk_get_local_flags(unsafe.Pointer(rblk))
+		action := rctlblk_get_local_action(unsafe.Pointer(rblk))
+		if (lflags&_RCTL_LOCAL_MAXIMAL) == 0 && action == _RCTL_LOCAL_DENY {
+			// This is a finite (not maximal) value representing a
+			// cap (deny) action.
+			v := rctlblk_get_value(unsafe.Pointer(rblk))
+			if capval == 0 || capval > v {
+				capval = v
+			}
+		}
+
+		// Swap the blocks around so that we can fetch the next value
+		t := rblk
+		rblk = rblkprev
+		rblkprev = t
+		flag = _RCTL_NEXT
+	}
+
+	return capval
+}
+
+func getncpu() int32 {
+	n := int32(sysconf(__SC_NPROCESSORS_ONLN))
+	if n < 1 {
+		return 1
+	}
+
+	if cents := int32(getcpucap()); cents > 0 {
+		// Convert from a percentage of CPUs to a number of CPUs,
+		// rounding up to make use of a fractional CPU
+		// e.g., 336% becomes 4 CPUs
+		ncap := (cents + 99) / 100
+		if ncap < n {
+			return ncap
+		}
+	}
+
+	return n
+}
+
+//go:nosplit
+func getrctl(controlname, oldbuf, newbuf unsafe.Pointer, flags uint32) uintptr {
+	return sysvicall4(&libc_getrctl, uintptr(controlname), uintptr(oldbuf), uintptr(newbuf), uintptr(flags))
+}
+
+//go:nosplit
+func rctlblk_get_local_action(buf unsafe.Pointer) uintptr {
+	return sysvicall2(&libc_rctlblk_get_local_action, uintptr(buf), uintptr(0))
+}
+
+//go:nosplit
+func rctlblk_get_local_flags(buf unsafe.Pointer) uintptr {
+	return sysvicall1(&libc_rctlblk_get_local_flags, uintptr(buf))
+}
+
+//go:nosplit
+func rctlblk_get_value(buf unsafe.Pointer) uint64 {
+	return uint64(sysvicall1(&libc_rctlblk_get_value, uintptr(buf)))
+}
+
+//go:nosplit
+func rctlblk_size() uintptr {
+	return sysvicall0(&libc_rctlblk_size)
+}