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Don't create an extra fd bitmap to allocate a new fd.

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This commit is contained in:
Andrei Vagin
2021-07-27 13:16:02 +08:00
committed by Howard Zhang
parent c8d252466f
commit 68cf8cc9a2
9 changed files with 207 additions and 74 deletions
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pkg/bitmap/BUILD
-2
View File
@@ -6,7 +6,6 @@ go_library(
name = "bitmap",
srcs = ["bitmap.go"],
visibility = ["//:sandbox"],
deps = ["@org_golang_x_sys//unix:go_default_library"],
)
go_test(
@@ -14,5 +13,4 @@ go_test(
size = "small",
srcs = ["bitmap_test.go"],
library = ":bitmap",
deps = ["@org_golang_x_sys//unix:go_default_library"],
)
pkg/bitmap/bitmap.go
+28 -6
View File
@@ -25,7 +25,7 @@ import (
// +stateify savable
type Bitmap struct {
// numOnes is the number of ones in the bitmap.
numOnes uint32
numOnes uint32
// bitBlock holds the bits. The type of bitBlock is uint64 which means
// each number in bitBlock contains 64 entries.
@@ -56,6 +56,28 @@ func (b *Bitmap) Minimum() uint32 {
return math.MaxInt32
}
// FirstZero returns the first unset bit from the range [start, ).
func (b *Bitmap) FirstZero(start uint32) uint32 {
i, nbit := int(start/64), start%64
n := len(b.bitBlock)
if i >= n {
return math.MaxInt32
}
w := b.bitBlock[i] | ((1 << nbit) - 1)
for {
if w != ^uint64(0) {
r := bits.TrailingZeros64(^w)
return uint32(r + i*64)
}
i++
if i == n {
break
}
w = b.bitBlock[i]
}
return math.MaxInt32
}
// Maximum return the largest value in the Bitmap.
func (b *Bitmap) Maximum() uint32 {
for i := len(b.bitBlock) - 1; i >= 0; i-- {
@@ -127,13 +149,13 @@ func (b *Bitmap) flipRange(begin, end uint32) {
beginBlock := begin / 64
endBlock := end / 64
if beginBlock == endBlock {
b.bitBlock[endBlock] ^= ((^uint64(0) << uint(begin%64)) & ((uint64(1) << (uint(end) % 64 + 1))-1))
b.bitBlock[endBlock] ^= ((^uint64(0) << uint(begin%64)) & ((uint64(1) << (uint(end)%64 + 1)) - 1))
} else {
b.bitBlock[beginBlock] ^= ^(^uint64(0) << uint(begin%64))
for i := beginBlock; i < endBlock; i++ {
b.bitBlock[i] = ^b.bitBlock[i]
}
b.bitBlock[endBlock] ^= ((uint64(1) << (uint(end) % 64 + 1))-1)
b.bitBlock[endBlock] ^= ((uint64(1) << (uint(end)%64 + 1)) - 1)
}
}
@@ -143,13 +165,13 @@ func (b *Bitmap) clearRange(begin, end uint32) {
beginBlock := begin / 64
endBlock := end / 64
if beginBlock == endBlock {
b.bitBlock[beginBlock] &= (((uint64(1) << uint(begin%64)) - 1) | ^((uint64(1) << (uint(end) % 64 + 1)) - 1))
b.bitBlock[beginBlock] &= (((uint64(1) << uint(begin%64)) - 1) | ^((uint64(1) << (uint(end)%64 + 1)) - 1))
} else {
b.bitBlock[beginBlock] &= ((uint64(1) << uint(begin%64)) - 1)
for i := beginBlock + 1; i < endBlock; i++ {
b.bitBlock[i] &= ^b.bitBlock[i]
}
b.bitBlock[endBlock] &= ^((uint64(1) << (uint(end) % 64 + 1)) - 1)
b.bitBlock[endBlock] &= ^((uint64(1) << (uint(end)%64 + 1)) - 1)
}
}
@@ -198,7 +220,7 @@ func (b *Bitmap) ToSlice() []uint32 {
// Extract the lowest set 1 bit.
j := bitBlock & -bitBlock
// Interpret the bit as the in32 number it represents and add it to result.
bitmapSlice = append(bitmapSlice, uint32((base + int(bits.OnesCount64(j - 1)))))
bitmapSlice = append(bitmapSlice, uint32((base + int(bits.OnesCount64(j-1)))))
bitBlock ^= j
}
base += 64
pkg/bitmap/bitmap_test.go
+41 -29
View File
@@ -15,6 +15,7 @@
package bitmap
import (
"math"
"reflect"
"testing"
)
@@ -29,9 +30,9 @@ func generateFilledSlice(min, max, length int) []uint32 {
}
randSlice := make([]uint32, length)
if length != 0 {
rangeNum := uint32((max - min)/length)
rangeNum := uint32((max - min) / length)
randSlice[0], randSlice[length-1] = uint32(min), uint32(max)
for i := 1 ; i < length - 1; i++ {
for i := 1; i < length-1; i++ {
randSlice[i] = randSlice[i-1] + rangeNum
}
}
@@ -50,9 +51,9 @@ func generateFilledBitmap(min, max, fillNum int) ([]uint32, Bitmap) {
}
func TestNewBitmap(t *testing.T) {
tests := []struct {
name string
size int
tests := []struct {
name string
size int
expectSize int
}{
{"length 1", 1, 1},
@@ -62,7 +63,7 @@ func TestNewBitmap(t *testing.T) {
for _, tt := range tests {
tt := tt
t.Run(tt.name, func(t *testing.T){
t.Run(tt.name, func(t *testing.T) {
if bitmap := BitmapWithSize(uint32(tt.size)); len(bitmap.bitBlock) != tt.expectSize {
t.Errorf("BitmapWithSize created bitmap with %v, bitBlock size: %d, wanted: %d", tt.name, len(bitmap.bitBlock), tt.expectSize)
}
@@ -72,14 +73,14 @@ func TestNewBitmap(t *testing.T) {
func TestAdd(t *testing.T) {
tests := []struct {
name string
name string
bitmapSize int
addNum int
addNum int
}{
{"Add with null bitmap.bitBlock", 0, 10},
{"Add without extending bitBlock",64, 10},
{"Add without extending bitBlock", 64, 10},
{"Add without extending bitblock with margin number", 63, 64},
{"Add with extended one block",1024, 1025},
{"Add with extended one block", 1024, 1025},
{"Add with extended more then one block", 1024, 2048},
}
@@ -110,14 +111,14 @@ func TestRemove(t *testing.T) {
}
bitmapSlice := bitmap.ToSlice()
if !reflect.DeepEqual(bitmapSlice, secondSlice) {
t.Errorf("After Remove() firstSlice, remained slice: %v, wanted: %v", bitmapSlice, secondSlice)
t.Errorf("After Remove() firstSlice, remained slice: %v, wanted: %v", bitmapSlice, secondSlice)
}
for i := 0; i < 50; i++ {
bitmap.Remove(secondSlice[i])
}
bitmapSlice = bitmap.ToSlice()
emptySlice := make([]uint32,0)
emptySlice := make([]uint32, 0)
if !reflect.DeepEqual(bitmapSlice, emptySlice) {
t.Errorf("After Remove secondSlice, remained slice: %v, wanted: %v", bitmapSlice, emptySlice)
}
@@ -127,9 +128,9 @@ func TestRemove(t *testing.T) {
// Verify flip bits within one bitBlock, one bit and bits cross multi bitBlocks.
func TestFlipRange(t *testing.T) {
tests := []struct {
name string
flipRangeMin int
flipRangeMax int
name string
flipRangeMin int
flipRangeMax int
filledSliceLen int
}{
{"Flip one number in bitmap", 77, 77, 1},
@@ -141,7 +142,7 @@ func TestFlipRange(t *testing.T) {
tt := tt
t.Run(tt.name, func(t *testing.T) {
fillSlice, bitmap := generateFilledBitmap(tt.flipRangeMin, tt.flipRangeMax, tt.filledSliceLen)
flipFillSlice := make([]uint32,0)
flipFillSlice := make([]uint32, 0)
for i, j := tt.flipRangeMin, 0; i <= tt.flipRangeMax; i++ {
if uint32(i) != fillSlice[j] {
flipFillSlice = append(flipFillSlice, uint32(i))
@@ -150,7 +151,7 @@ func TestFlipRange(t *testing.T) {
}
}
bitmap.FlipRange(uint32(tt.flipRangeMin), uint32(tt.flipRangeMax + 1))
bitmap.FlipRange(uint32(tt.flipRangeMin), uint32(tt.flipRangeMax+1))
flipBitmapSlice := bitmap.ToSlice()
if !reflect.DeepEqual(flipFillSlice, flipBitmapSlice) {
t.Errorf("%v, flipped slice: %v, wanted: %v", tt.name, flipBitmapSlice, flipFillSlice)
@@ -162,10 +163,10 @@ func TestFlipRange(t *testing.T) {
// Verify clear bits within one bitBlock, one bit and bits cross multi bitBlocks.
func TestClearRange(t *testing.T) {
tests := []struct {
name string
name string
clearRangeMin int
clearRangeMax int
bitmapSize int
bitmapSize int
}{
{"ClearRange clear one number", 5, 5, 64},
{"ClearRange clear numbers within one bitBlock", 4, 61, 64},
@@ -177,9 +178,9 @@ func TestClearRange(t *testing.T) {
t.Run(tt.name, func(t *testing.T) {
bitmap := BitmapWithSize(uint32(tt.bitmapSize))
bitmap.FlipRange(uint32(0), uint32(tt.bitmapSize))
bitmap.ClearRange(uint32(tt.clearRangeMin), uint32(tt.clearRangeMax + 1))
bitmap.ClearRange(uint32(tt.clearRangeMin), uint32(tt.clearRangeMax+1))
clearedBitmapSlice := bitmap.ToSlice()
clearedSlice := make([]uint32,0)
clearedSlice := make([]uint32, 0)
for i := 0; i < tt.bitmapSize; i++ {
if i < tt.clearRangeMin || i > tt.clearRangeMax {
clearedSlice = append(clearedSlice, uint32(i))
@@ -218,22 +219,22 @@ func TestMinimum(t *testing.T) {
func TestMaximum(t *testing.T) {
randSlice, bitmap := generateFilledBitmap(0, 1024, 200)
max := bitmap.Maximum()
if max != randSlice[len(randSlice) - 1] {
t.Errorf("Maximum() returns: %v, wanted: %v", max, randSlice[len(randSlice) - 1])
if max != randSlice[len(randSlice)-1] {
t.Errorf("Maximum() returns: %v, wanted: %v", max, randSlice[len(randSlice)-1])
}
bitmap.ClearRange(uint32(1000), uint32(1025))
max = bitmap.Maximum()
bitmapSlice := bitmap.ToSlice()
if max != bitmapSlice[len(bitmapSlice) - 1] {
t.Errorf("After ClearRange, Maximum() returns: %v, wanted: %v", max, bitmapSlice[len(bitmapSlice) - 1])
if max != bitmapSlice[len(bitmapSlice)-1] {
t.Errorf("After ClearRange, Maximum() returns: %v, wanted: %v", max, bitmapSlice[len(bitmapSlice)-1])
}
bitmap.FlipRange(uint32(1001), uint32(1021))
max = bitmap.Maximum()
bitmapSlice = bitmap.ToSlice()
if max != bitmapSlice[len(bitmapSlice) - 1] {
t.Errorf("After Flip, Maximum() returns: %v, wanted: %v", max, bitmapSlice[len(bitmapSlice) - 1])
if max != bitmapSlice[len(bitmapSlice)-1] {
t.Errorf("After Flip, Maximum() returns: %v, wanted: %v", max, bitmapSlice[len(bitmapSlice)-1])
}
}
@@ -261,7 +262,7 @@ func TestBitmapNumOnes(t *testing.T) {
}
// Add 10 number.
for i := 1080; i < 1090; i++{
for i := 1080; i < 1090; i++ {
bitmap.Add(uint32(i))
}
bitmapOnes = bitmap.GetNumOnes()
@@ -270,7 +271,7 @@ func TestBitmapNumOnes(t *testing.T) {
}
// Add the 10 number again, the length supposed not change.
for i := 1080; i < 1090; i++{
for i := 1080; i < 1090; i++ {
bitmap.Add(uint32(i))
}
bitmapOnes = bitmap.GetNumOnes()
@@ -292,3 +293,14 @@ func TestBitmapNumOnes(t *testing.T) {
t.Errorf("After ClearRange, GetNumOnes() returns: %v, wanted: %v", bitmapOnes, 20)
}
}
func TestFirstZero(t *testing.T) {
bitmap := BitmapWithSize(uint32(1000))
bitmap.FlipRange(200, 400)
for i, j := range map[uint32]uint32{0: 0, 201: 400, 200: 400, 199: 199, 400: 400, 10000: math.MaxInt32} {
v := bitmap.FirstZero(i)
if v != j {
t.Errorf("Minimum() returns: %v, wanted: %v", v, j)
}
}
}
pkg/sentry/kernel/fd_table.go
+19 -37
View File
@@ -271,7 +271,7 @@ func (f *FDTable) NewFDs(ctx context.Context, minFD int32, files []*fs.File, fla
if lim.Cur != limits.Infinity {
end = int32(lim.Cur)
}
if minFD >= end {
if minFD+int32(len(files)) > end {
return nil, unix.EMFILE
}
}
@@ -280,17 +280,10 @@ func (f *FDTable) NewFDs(ctx context.Context, minFD int32, files []*fs.File, fla
// max is used as the largest number in fdBitmap + 1.
max := int32(0)
// flipFdBitmap is flip of fdBitmap which is used to find free fd in fdBitmap.
flipFdBitmap := f.fdBitmap.Clone()
if !f.fdBitmap.IsEmpty() {
max = int32(f.fdBitmap.Maximum())
max++
flipFdBitmap.FlipRange(uint32(0), uint32(max))
// Clear 0 to (minFD-1) bit in flipFdBitmap, thus it will not use fd that is less than minFD.
if minFD > 0 {
flipFdBitmap.ClearRange(uint32(0), uint32(minFD))
}
}
// Adjust max in case it is less than minFD.
@@ -301,20 +294,18 @@ func (f *FDTable) NewFDs(ctx context.Context, minFD int32, files []*fs.File, fla
for len(fds) < len(files) {
// Try to use free bit in fdBitmap.
// If all bits in fdBitmap are used, expand fd to the max.
if !flipFdBitmap.IsEmpty() {
fd := flipFdBitmap.Minimum()
f.fdBitmap.Add(fd)
flipFdBitmap.Remove(fd)
f.set(ctx, int32(fd), files[len(fds)], flags)
fds = append(fds, int32(fd))
} else if max < end {
f.fdBitmap.Add(uint32(max))
f.set(ctx, max, files[len(fds)], flags)
fds = append(fds, max)
fd := f.fdBitmap.FirstZero(uint32(minFD))
if fd == math.MaxInt32 {
fd = uint32(max)
max++
} else {
}
if fd >= uint32(end) {
break
}
f.fdBitmap.Add(fd)
f.set(ctx, int32(fd), files[len(fds)], flags)
fds = append(fds, int32(fd))
minFD = int32(fd)
}
// Failure? Unwind existing FDs.
@@ -366,17 +357,10 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, minFD int32, files []*vfs.File
// max is used as the largest number in fdBitmap + 1.
max := int32(0)
// flipFdBitmap is flip of fdBitmap which is used to find free fd in fdBitmap.
flipFdBitmap := f.fdBitmap.Clone()
if !f.fdBitmap.IsEmpty() {
max = int32(f.fdBitmap.Maximum())
max++
flipFdBitmap.FlipRange(uint32(0), uint32(max))
// Clear 0 to (minFD-1) bit in flipFdBitmap, thus it will not use fd that is less than minFD.
if minFD > 0 {
flipFdBitmap.ClearRange(uint32(0), uint32(minFD))
}
}
// Adjust max in case it is less than minFD.
@@ -387,20 +371,18 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, minFD int32, files []*vfs.File
for len(fds) < len(files) {
// Try to use free bit in fdBitmap.
// If all bits in fdBitmap are used, expand fd to the max.
if !flipFdBitmap.IsEmpty() {
fd := flipFdBitmap.Minimum()
f.fdBitmap.Add(fd)
flipFdBitmap.Remove(fd)
f.setVFS2(ctx, int32(fd), files[len(fds)], flags)
fds = append(fds, int32(fd))
} else if max < end {
f.fdBitmap.Add(uint32(max))
f.setVFS2(ctx, max, files[len(fds)], flags)
fds = append(fds, max)
fd := f.fdBitmap.FirstZero(uint32(minFD))
if fd == math.MaxInt32 {
fd = uint32(max)
max++
} else {
}
if fd >= uint32(end) {
break
}
f.fdBitmap.Add(fd)
f.setVFS2(ctx, int32(fd), files[len(fds)], flags)
fds = append(fds, int32(fd))
minFD = int32(fd)
}
// Failure? Unwind existing FDs.
if len(fds) < len(files) {
test/perf/BUILD
+7
View File
@@ -69,6 +69,13 @@ syscall_test(
test = "//test/perf/linux:open_benchmark",
)
syscall_test(
size = "large",
add_overlay = True,
debug = False,
test = "//test/perf/linux:dup_benchmark",
)
syscall_test(
debug = False,
test = "//test/perf/linux:pipe_benchmark",
test/perf/linux/BUILD
+16
View File
@@ -108,6 +108,22 @@ cc_binary(
],
)
cc_binary(
name = "dup_benchmark",
testonly = 1,
srcs = [
"dup_benchmark.cc",
],
deps = [
gbenchmark,
gtest,
"//test/util:fs_util",
"//test/util:logging",
"//test/util:temp_path",
"//test/util:test_main",
],
)
cc_binary(
name = "read_benchmark",
testonly = 1,
test/perf/linux/dup_benchmark.cc
+57
View File
@@ -0,0 +1,57 @@
// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include "gtest/gtest.h"
#include "benchmark/benchmark.h"
#include "test/util/fs_util.h"
#include "test/util/logging.h"
#include "test/util/temp_path.h"
namespace gvisor {
namespace testing {
namespace {
void BM_Dup(benchmark::State& state) {
const int size = state.range(0);
for (auto _ : state) {
std::vector<int> v;
for (int i = 0; i < size; i++) {
int fd = dup(2);
TEST_CHECK(fd != -1);
v.push_back(fd);
}
for (int i = 0; i < size; i++) {
int fd = v[i];
close(fd);
}
}
state.SetItemsProcessed(state.iterations() * size);
}
BENCHMARK(BM_Dup)->Range(1, 1 << 15)->UseRealTime();
} // namespace
} // namespace testing
} // namespace gvisor
test/syscalls/linux/BUILD
+1
View File
@@ -583,6 +583,7 @@ cc_binary(
deps = [
"//test/util:eventfd_util",
"//test/util:file_descriptor",
"@com_google_absl//absl/memory",
gtest,
"//test/util:fs_util",
"//test/util:posix_error",
test/syscalls/linux/dup.cc
+38
View File
@@ -13,9 +13,11 @@
// limitations under the License.
#include <fcntl.h>
#include <sys/resource.h>
#include <unistd.h>
#include "gtest/gtest.h"
#include "absl/memory/memory.h"
#include "test/util/eventfd_util.h"
#include "test/util/file_descriptor.h"
#include "test/util/fs_util.h"
@@ -98,6 +100,42 @@ TEST(DupTest, Dup2) {
ASSERT_NO_ERRNO(CheckSameFile(fd, nfd2));
}
TEST(DupTest, Rlimit) {
constexpr int kFDLimit = 101;
auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));
struct rlimit rl = {};
EXPECT_THAT(getrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
// Lower the rlimit first, as it may be equal to /proc/sys/fs/nr_open, in
// which case even users with CAP_SYS_RESOURCE can't raise it.
rl.rlim_cur = kFDLimit * 2;
ASSERT_THAT(setrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
FileDescriptor aboveLimitFD =
ASSERT_NO_ERRNO_AND_VALUE(Dup2(fd, kFDLimit * 2 - 1));
rl.rlim_cur = kFDLimit;
ASSERT_THAT(setrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
ASSERT_THAT(dup3(fd.get(), kFDLimit, 0), SyscallFails());
std::vector<std::unique_ptr<FileDescriptor>> fds;
int prev = fd.get();
for (int i = 0; i < kFDLimit; i++) {
int d = dup(fd.get());
if (d == -1) {
break;
}
std::unique_ptr<FileDescriptor> f = absl::make_unique<FileDescriptor>(d);
EXPECT_LT(d, kFDLimit);
EXPECT_GT(d, prev);
prev = d;
fds.push_back(std::move(f));
}
EXPECT_EQ(fds.size(), kFDLimit - fd.get() - 1);
}
TEST(DupTest, Dup2SameFD) {
auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));