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Reduce kmalloc() traffic in directory iteration.

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Pass the file name in a stack-allocated buffer instead of using an AK::String
when iterating directories. This dramatically reduces the amount of cycles
spent traversing the filesystem.
This commit is contained in:
Andreas Kling 2018-11-13 00:17:30 +01:00
parent 5e8e554f94
commit 19b9401487
10 changed files with 60 additions and 40 deletions
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37
VirtualFileSystem/Ext2FileSystem.cpp
View file

@ -211,7 +211,7 @@ auto Ext2FileSystem::lookupExt2Inode(unsigned inode) const -> CachedExt2Inode
#endif
LOCKER(m_inodeCacheLock);
if (m_inodeCache.size() >= 64)
if (m_inodeCache.size() >= 128)
m_inodeCache.removeOneRandomly();
auto cachedInode = adopt(*new CachedExt2InodeImpl(OwnPtr<ext2_inode>(e2inode)));
m_inodeCache.set(inode, cachedInode.copyRef());
@ -261,14 +261,14 @@ Vector<unsigned> Ext2FileSystem::blockListForInode(const ext2_inode& e2inode) co
unsigned directCount = min(blockCount, (unsigned)EXT2_NDIR_BLOCKS);
for (unsigned i = 0; i < directCount; ++i) {
list.append(e2inode.i_block[i]);
list.unchecked_append(e2inode.i_block[i]);
--blocksRemaining;
}
if (!blocksRemaining)
return list;
auto processBlockArray = [&] (unsigned arrayBlockIndex, Function<void(unsigned)> callback) {
auto processBlockArray = [&] (unsigned arrayBlockIndex, auto&& callback) {
auto arrayBlock = readBlock(arrayBlockIndex);
ASSERT(arrayBlock);
auto* array = reinterpret_cast<const __u32*>(arrayBlock.pointer());
@ -284,7 +284,7 @@ Vector<unsigned> Ext2FileSystem::blockListForInode(const ext2_inode& e2inode) co
};
processBlockArray(e2inode.i_block[EXT2_IND_BLOCK], [&] (unsigned entry) {
list.append(entry);
list.unchecked_append(entry);
});
if (!blocksRemaining)
@ -292,7 +292,7 @@ Vector<unsigned> Ext2FileSystem::blockListForInode(const ext2_inode& e2inode) co
processBlockArray(e2inode.i_block[EXT2_DIND_BLOCK], [&] (unsigned entry) {
processBlockArray(entry, [&] (unsigned entry) {
list.append(entry);
list.unchecked_append(entry);
});
});
@ -302,7 +302,7 @@ Vector<unsigned> Ext2FileSystem::blockListForInode(const ext2_inode& e2inode) co
processBlockArray(e2inode.i_block[EXT2_TIND_BLOCK], [&] (unsigned entry) {
processBlockArray(entry, [&] (unsigned entry) {
processBlockArray(entry, [&] (unsigned entry) {
list.append(entry);
list.unchecked_append(entry);
});
});
});
@ -434,16 +434,12 @@ bool Ext2FileSystem::enumerateDirectoryInode(InodeIdentifier inode, Function<boo
ASSERT(buffer);
auto* entry = reinterpret_cast<ext2_dir_entry_2*>(buffer.pointer());
char namebuf[EXT2_NAME_LEN + 1];
while (entry < buffer.endPointer()) {
if (entry->inode != 0) {
memcpy(namebuf, entry->name, entry->name_len);
namebuf[entry->name_len] = 0;
#ifdef EXT2_DEBUG
kprintf("inode: %u, name_len: %u, rec_len: %u, file_type: %u, name: %s\n", entry->inode, entry->name_len, entry->rec_len, entry->file_type, namebuf);
#endif
if (!callback({ namebuf, { id(), entry->inode }, entry->file_type }))
if (!callback({ entry->name, entry->name_len, { id(), entry->inode }, entry->file_type }))
break;
}
entry = (ext2_dir_entry_2*)((char*)entry + entry->rec_len);
@ -464,7 +460,7 @@ bool Ext2FileSystem::addInodeToDirectory(unsigned directoryInode, unsigned inode
Vector<DirectoryEntry> entries;
bool nameAlreadyExists = false;
enumerateDirectoryInode({ id(), directoryInode }, [&] (const DirectoryEntry& entry) {
if (entry.name == name) {
if (!strcmp(entry.name, name.characters())) {
nameAlreadyExists = true;
return false;
}
@ -476,8 +472,7 @@ bool Ext2FileSystem::addInodeToDirectory(unsigned directoryInode, unsigned inode
return false;
}
entries.append({ name, { id(), inode }, fileType });
entries.append({ name.characters(), name.length(), { id(), inode }, fileType });
return writeDirectoryInode(directoryInode, move(entries));
}
@ -487,8 +482,8 @@ bool Ext2FileSystem::writeDirectoryInode(unsigned directoryInode, Vector<Directo
unsigned directorySize = 0;
for (auto& entry : entries) {
kprintf(" - %08u %s\n", entry.inode.index(), entry.name.characters());
directorySize += EXT2_DIR_REC_LEN(entry.name.length());
kprintf(" - %08u %s\n", entry.inode.index(), entry.name);
directorySize += EXT2_DIR_REC_LEN(entry.name_length);
}
unsigned blocksNeeded = ceilDiv(directorySize, blockSize());
@ -502,23 +497,23 @@ bool Ext2FileSystem::writeDirectoryInode(unsigned directoryInode, Vector<Directo
for (unsigned i = 0; i < entries.size(); ++i) {
auto& entry = entries[i];
unsigned recordLength = EXT2_DIR_REC_LEN(entry.name.length());
unsigned recordLength = EXT2_DIR_REC_LEN(entry.name_length);
if (i == entries.size() - 1)
recordLength += occupiedSize - directorySize;
kprintf("* inode: %u", entry.inode.index());
kprintf(", name_len: %u", word(entry.name.length()));
kprintf(", name_len: %u", word(entry.name_length));
kprintf(", rec_len: %u", word(recordLength));
kprintf(", file_type: %u", byte(entry.fileType));
kprintf(", name: %s\n", entry.name.characters());
kprintf(", name: %s\n", entry.name);
stream << dword(entry.inode.index());
stream << word(recordLength);
stream << byte(entry.name.length());
stream << byte(entry.name_length);
stream << byte(entry.fileType);
stream << entry.name;
unsigned padding = recordLength - entry.name.length() - 8;
unsigned padding = recordLength - entry.name_length - 8;
kprintf(" *** pad %u bytes\n", padding);
for (unsigned j = 0; j < padding; ++j) {
stream << byte(0);

2
VirtualFileSystem/FileDescriptor.cpp
View file

@ -218,7 +218,7 @@ ssize_t FileDescriptor::get_dir_entries(byte* buffer, Unix::size_t size)
m_vnode->vfs()->enumerateDirectoryInode(m_vnode->inode, [&stream] (auto& entry) {
stream << (dword)entry.inode.index();
stream << (byte)entry.fileType;
stream << (dword)entry.name.length();
stream << (dword)entry.name_length;
stream << entry.name;
return true;
});

19
VirtualFileSystem/FileSystem.cpp
View file

@ -41,7 +41,7 @@ InodeIdentifier FileSystem::childOfDirectoryInodeWithName(InodeIdentifier inode,
{
InodeIdentifier foundInode;
enumerateDirectoryInode(inode, [&] (const DirectoryEntry& entry) {
if (entry.name == name) {
if (!strcmp(entry.name, name.characters())) {
foundInode = entry.inode;
return false;
}
@ -101,3 +101,20 @@ ByteBuffer FileSystem::readEntireInode(InodeIdentifier inode, FileDescriptor* ha
return contents;
}
FileSystem::DirectoryEntry::DirectoryEntry(const char* n, InodeIdentifier i, byte ft)
: name_length(strlen(name))
, inode(i)
, fileType(ft)
{
memcpy(name, n, name_length);
name[name_length] = '\0';
}
FileSystem::DirectoryEntry::DirectoryEntry(const char* n, Unix::size_t nl, InodeIdentifier i, byte ft)
: name_length(nl)
, inode(i)
, fileType(ft)
{
memcpy(name, n, nl);
name[nl] = '\0';
}

5
VirtualFileSystem/FileSystem.h
View file

@ -35,7 +35,10 @@ public:
virtual Unix::ssize_t readInodeBytes(InodeIdentifier, Unix::off_t offset, Unix::size_t count, byte* buffer, FileDescriptor*) const = 0;
struct DirectoryEntry {
String name;
DirectoryEntry(const char* name, InodeIdentifier, byte fileType);
DirectoryEntry(const char* name, Unix::size_t name_length, InodeIdentifier, byte fileType);
char name[256];
Unix::size_t name_length { 0 };
InodeIdentifier inode;
byte fileType { 0 };
};

6
VirtualFileSystem/SyntheticFileSystem.cpp
View file

@ -147,11 +147,11 @@ bool SyntheticFileSystem::enumerateDirectoryInode(InodeIdentifier inode, Functio
if (!synInode.metadata.isDirectory())
return false;
callback({ ".", synInode.metadata.inode });
callback({ "..", synInode.parent });
callback({ ".", 1, synInode.metadata.inode, 2 });
callback({ "..", 2, synInode.parent, 2 });
for (auto& child : synInode.children)
callback({ child->name, child->metadata.inode });
callback({ child->name.characters(), child->name.length(), child->metadata.inode, child->metadata.isDirectory() ? (byte)2 : (byte)1 });
return true;
}

10
VirtualFileSystem/VirtualFileSystem.cpp
View file

@ -250,12 +250,12 @@ void VirtualFileSystem::enumerateDirectoryInode(InodeIdentifier directoryInode,
else
resolvedInode = entry.inode;
if (directoryInode.isRootInode() && !isRoot(directoryInode) && entry.name == "..") {
if (directoryInode.isRootInode() && !isRoot(directoryInode) && !strcmp(entry.name, "..")) {
auto mount = findMountForGuest(entry.inode);
ASSERT(mount);
resolvedInode = mount->host();
}
callback({ entry.name, resolvedInode });
callback(FileSystem::DirectoryEntry(entry.name, entry.name_length, resolvedInode, entry.fileType));
return true;
});
}
@ -348,7 +348,7 @@ void VirtualFileSystem::listDirectory(const String& path, InodeIdentifier base)
kprintf("%s%s%s",
nameColorBegin,
entry.name.characters(),
entry.name,
nameColorEnd);
if (metadata.isDirectory()) {
@ -376,11 +376,11 @@ void VirtualFileSystem::listDirectoryRecursively(const String& path, InodeIdenti
if (metadata.isDirectory()) {
if (entry.name != "." && entry.name != "..") {
char buf[4096];
ksprintf(buf, "%s/%s", path.characters(), entry.name.characters());
ksprintf(buf, "%s/%s", path.characters(), entry.name);
listDirectoryRecursively(buf, base);
}
} else {
kprintf("%s/%s\n", path.characters(), entry.name.characters());
kprintf("%s/%s\n", path.characters(), entry.name);
}
return true;
});