From 04b08da9af0c450d645ab7389d1467308cfc2db8 Mon Sep 17 00:00:00 2001 From: Michael Stapelberg Date: Mon, 4 Mar 2013 21:27:36 +0100 Subject: Imported Upstream version 1.1~hg20130304 --- src/pkg/runtime/time_plan9_386.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 src/pkg/runtime/time_plan9_386.c (limited to 'src/pkg/runtime/time_plan9_386.c') diff --git a/src/pkg/runtime/time_plan9_386.c b/src/pkg/runtime/time_plan9_386.c new file mode 100644 index 000000000..a29d45715 --- /dev/null +++ b/src/pkg/runtime/time_plan9_386.c @@ -0,0 +1,34 @@ +// Copyright 2010 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. + +#include "runtime.h" +#include "os_GOOS.h" + +int64 +runtime·nanotime(void) +{ + static int32 fd = -1; + byte b[8]; + uint32 hi, lo; + + // As long as all goroutines share the same file + // descriptor table we can get away with using + // just a static fd. Without a lock the file can + // be opened twice but that's okay. + // + // Using /dev/bintime gives us a latency on the + // order of ten microseconds between two calls. + // + // The naïve implementation (without the cached + // file descriptor) is roughly four times slower + // in 9vx on a 2.16 GHz Intel Core 2 Duo. + + if(fd < 0 && (fd = runtime·open((byte*)"/dev/bintime", OREAD|OCEXEC)) < 0) + return 0; + if(runtime·pread(fd, b, sizeof b, 0) != sizeof b) + return 0; + hi = b[0]<<24 | b[1]<<16 | b[2]<<8 | b[3]; + lo = b[4]<<24 | b[5]<<16 | b[6]<<8 | b[7]; + return (int64)hi<<32 | (int64)lo; +} -- cgit v1.2.3