mirror of
https://github.com/token2/snapd.git
synced 2026-03-13 11:15:47 -07:00
bf067f57db
Ideas employed
- reorder fields so that mask is before the string
- use POPCNT to estimate allocation size
- allocate late on demand
- pre-compute mask of known flags
- bail out when known flags are handled
This yields improvements in most of the benchmarks:
Before:
BenchmarkUnmountFlagsToOptsAllMissing-4 200000000 6.07 ns/op
BenchmarkUnmountFlagsToOptsMixed-4 50000000 36.8 ns/op
BenchmarkUnmountFlagsToOptsAllPresent-4 10000000 158 ns/op
BenchmarkMountFlagsToOptsAllMissing-4 200000000 9.93 ns/op
BenchmarkMountFlagsToOptsAllPresent-4 10000000 230 ns/op
BenchmarkMountFlagsToOptsMixed-4 30000000 41.4 ns/op
BenchmarkMountFlagsToOptsTypical-4 30000000 41.8 ns/op
After:
BenchmarkUnmountFlagsToOptsAllMissing-4 500000000 3.41 ns/op
BenchmarkUnmountFlagsToOptsMixed-4 30000000 54.3 ns/op
BenchmarkUnmountFlagsToOptsAllPresent-4 20000000 63.8 ns/op
BenchmarkMountFlagsToOptsAllMissing-4 500000000 3.71 ns/op
BenchmarkMountFlagsToOptsAllPresent-4 20000000 83.6 ns/op
BenchmarkMountFlagsToOptsMixed-4 20000000 51.5 ns/op
BenchmarkMountFlagsToOptsTypical-4 50000000 33.2 ns/op
I've also added a "typical" benchmark with one known flag only.
Signed-off-by: Zygmunt Krynicki <me@zygoon.pl>
116 lines
3.7 KiB
Go
116 lines
3.7 KiB
Go
// -*- Mode: Go; indent-tabs-mode: t -*-
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/*
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* Copyright (C) 2019 Canonical Ltd
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 3 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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package mount_test
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import (
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"syscall"
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"testing"
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. "gopkg.in/check.v1"
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"github.com/snapcore/snapd/osutil/mount"
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)
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func Test(t *testing.T) { TestingT(t) }
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type mountSuite struct{}
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var _ = Suite(&mountSuite{})
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func (s *mountSuite) TestMountFlagsToOpts(c *C) {
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// Known flags are converted to symbolic names.
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opts, unknown := mount.MountFlagsToOpts(syscall.MS_REMOUNT |
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syscall.MS_BIND | syscall.MS_REC | syscall.MS_RDONLY | syscall.MS_SHARED |
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syscall.MS_SLAVE | syscall.MS_PRIVATE | syscall.MS_UNBINDABLE)
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c.Check(opts, DeepEquals, []string{"MS_REMOUNT", "MS_BIND", "MS_REC",
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"MS_RDONLY", "MS_SHARED", "MS_SLAVE", "MS_PRIVATE", "MS_UNBINDABLE"})
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c.Check(unknown, Equals, 0)
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// Unknown flags are retained and returned.
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opts, unknown = mount.MountFlagsToOpts(1 << 24)
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c.Check(opts, DeepEquals, []string(nil))
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c.Check(unknown, Equals, 1<<24)
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// Known and unknown flags work in tandem.
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opts, unknown = mount.MountFlagsToOpts(syscall.MS_BIND | 1<<24)
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c.Check(opts, DeepEquals, []string{"MS_BIND"})
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c.Check(unknown, Equals, 1<<24)
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}
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func (s *mountSuite) TestUnmountFlagsToOpts(c *C) {
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// Known flags are converted to symbolic names.
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const UMOUNT_NOFOLLOW = 8
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opts, unknown := mount.UnmountFlagsToOpts(syscall.MNT_FORCE |
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syscall.MNT_DETACH | syscall.MNT_EXPIRE | UMOUNT_NOFOLLOW)
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c.Check(opts, DeepEquals, []string{"UMOUNT_NOFOLLOW", "MNT_FORCE",
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"MNT_DETACH", "MNT_EXPIRE"})
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c.Check(unknown, Equals, 0)
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// Unknown flags are retained and returned.
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opts, unknown = mount.UnmountFlagsToOpts(1 << 24)
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c.Check(opts, DeepEquals, []string(nil))
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c.Check(unknown, Equals, 1<<24)
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// Known and unknown flags work in tandem.
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opts, unknown = mount.UnmountFlagsToOpts(syscall.MNT_DETACH | 1<<24)
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c.Check(opts, DeepEquals, []string{"MNT_DETACH"})
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c.Check(unknown, Equals, 1<<24)
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}
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var benchResultOpt []string
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var benchResultUnknown int
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func benchUnmount(flags int, b *testing.B) {
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var opts []string
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var unknown int
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for n := 0; n < b.N; n++ {
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opts, unknown = mount.UnmountFlagsToOpts(flags)
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}
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benchResultOpt = opts
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benchResultUnknown = unknown
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}
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func benchMount(flags int, b *testing.B) {
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var opts []string
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var unknown int
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for n := 0; n < b.N; n++ {
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opts, unknown = mount.MountFlagsToOpts(flags)
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}
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benchResultOpt = opts
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benchResultUnknown = unknown
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}
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func BenchmarkUnmountFlagsToOptsAllMissing(b *testing.B) { benchUnmount(1<<24, b) }
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func BenchmarkUnmountFlagsToOptsMixed(b *testing.B) { benchUnmount(syscall.MNT_DETACH|1<<24, b) }
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func BenchmarkUnmountFlagsToOptsAllPresent(b *testing.B) {
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const UMOUNT_NOFOLLOW = 8
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benchUnmount(syscall.MNT_FORCE|
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syscall.MNT_DETACH|syscall.MNT_EXPIRE|UMOUNT_NOFOLLOW, b)
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}
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func BenchmarkMountFlagsToOptsAllMissing(b *testing.B) { benchMount(1<<24, b) }
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func BenchmarkMountFlagsToOptsAllPresent(b *testing.B) {
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benchMount(syscall.MS_REMOUNT|
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syscall.MS_BIND|syscall.MS_REC|syscall.MS_RDONLY|syscall.MS_SHARED|
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syscall.MS_SLAVE|syscall.MS_PRIVATE|syscall.MS_UNBINDABLE, b)
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}
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func BenchmarkMountFlagsToOptsMixed(b *testing.B) { benchMount(syscall.MS_BIND|1<<24, b) }
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func BenchmarkMountFlagsToOptsTypical(b *testing.B) {
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benchMount(syscall.MS_BIND, b)
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}
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