axeld:

* Implemented a way to do asynchronous pre-fetching when mapping files.
* There are slight code duplications in some places that could benefit
  from cleaning up, but nothing too bad.
* Implementing smarter ways to trigger prefetching and more analysis of
  the situations in the kernel would be nice. Currently up to 10 MB
  of every mapped file are pre-fetched without further analysis.
* The speed improvement is nice for certain operations. On our test
  system (real hardware), Firefox took 9 seconds from being launched
  to display a window. Now it takes 5 seconds. Both measurements
  right after booting. The same system took 35 seconds from launching
  Haiku in the GRUB menu to displaying the Tracker desktop background
  image. Now it takes 27 seconds.
* We didn't have the chance to check out the effects of this on the
  CD boot, but potentially, they could speed it up a lot.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30465 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vfs.h

@@ -286,6 +286,10 @@ protected:
 };
 
 
+status_t vfs_asynchronous_read_pages(struct vnode* vnode, void* cookie,
+			off_t pos, const iovec* vecs, size_t count, size_t numBytes,
+			uint32 flags, AsyncIOCallback* callback);
+
 status_t vfs_asynchronous_write_pages(struct vnode* vnode, void* cookie,
 			off_t pos, const iovec* vecs, size_t count, size_t numBytes,
 			uint32 flags, AsyncIOCallback* callback);

src/system/kernel/cache/file_cache.cpp

@@ -69,10 +69,37 @@ struct file_cache_ref {
 	}
 };
 
+class PrecacheIO : public AsyncIOCallback {
+public:
+								PrecacheIO(file_cache_ref* ref, off_t offset,
+									size_t size);
+								~PrecacheIO();
+
+			status_t			Init();
+			status_t			Start();
+
+	virtual	void				IOFinished(status_t status,
+									bool partialTransfer,
+									size_t bytesTransferred);
+
+private:
+			file_cache_ref*		fRef;
+			VMCache*			fCache;
+			vm_page**			fPages;
+			size_t				fPageCount;
+			ConditionVariable*	fBusyConditions;
+			iovec*				fVecs;
+			off_t				fOffset;
+			size_t				fSize;
+};
+
 typedef status_t (*cache_func)(file_cache_ref *ref, void *cookie, off_t offset,
 	int32 pageOffset, addr_t buffer, size_t bufferSize, bool useBuffer,
 	size_t lastReservedPages, size_t reservePages);
 
+static void add_to_iovec(iovec *vecs, uint32 &index, uint32 max, addr_t address,
+	size_t size);
+
 
 static struct cache_module_info *sCacheModule;
 static const uint8 kZeroBuffer[4096] = {};
@@ -81,8 +108,119 @@ static const uint8 kZeroBuffer[4096] = {};
 //	#pragma mark -
 
 
+PrecacheIO::PrecacheIO(file_cache_ref* ref, off_t offset, size_t size)
+	:
+	fRef(ref),
+	fCache(ref->cache),
+	fPages(NULL),
+	fBusyConditions(NULL),
+	fVecs(NULL),
+	fOffset(offset),
+	fSize(size)
+{
+	fPageCount = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
+	fCache->AcquireRefLocked();
+}
+
+
+PrecacheIO::~PrecacheIO()
+{
+	delete[] fPages;
+	delete[] fBusyConditions;
+	delete[] fVecs;
+	fCache->ReleaseRefLocked();
+}
+
+
+status_t
+PrecacheIO::Init()
+{
+	if (fPageCount == 0)
+		return B_BAD_VALUE;
+
+	fPages = new(std::nothrow) vm_page*[fPageCount];
+	if (fPages == NULL)
+		return B_NO_MEMORY;
+
+	fBusyConditions = new(std::nothrow) ConditionVariable[fPageCount];
+	if (fBusyConditions == NULL)
+		return B_NO_MEMORY;
+
+	fVecs = new(std::nothrow) iovec[fPageCount];
+	if (fVecs == NULL)
+		return B_NO_MEMORY;
+
+	return B_OK;
+}
+
+
+//!	Cache has to be locked when calling this method.
+status_t
+PrecacheIO::Start()
+{
+	// allocate pages for the cache and mark them busy
+	uint32 vecCount = 0;
+	uint32 i = 0;
+	for (size_t pos = 0; pos < fSize; pos += B_PAGE_SIZE) {
+		vm_page* page = fPages[i++] = vm_page_allocate_page(
+			PAGE_STATE_FREE, true);
+		if (page == NULL)
+			break;
+
+		fBusyConditions[i - 1].Publish(page, "page");
+
+		fCache->InsertPage(page, fOffset + pos);
+
+		add_to_iovec(fVecs, vecCount, fPageCount,
+			page->physical_page_number * B_PAGE_SIZE, B_PAGE_SIZE);
+	}
+
+	if (i != fPageCount) {
+		// allocating pages failed
+		while (i-- > 0) {
+			fBusyConditions[i].Unpublish();
+			fCache->RemovePage(fPages[i]);
+			vm_page_set_state(fPages[i], PAGE_STATE_FREE);
+		}
+		return B_NO_MEMORY;
+	}
+
+	return vfs_asynchronous_read_pages(fRef->vnode, NULL, fOffset, fVecs,
+		vecCount, fSize, B_PHYSICAL_IO_REQUEST, this);
+}
+
+
+void
+PrecacheIO::IOFinished(status_t status, bool partialTransfer,
+	size_t bytesTransferred)
+{
+	AutoLocker<VMCache> locker(fCache);
+
+	// Make successfully loaded pages accessible again (partially
+	// transferred pages are considered failed)
+	size_t pagesTransferred = bytesTransferred >> PAGE_SHIFT;
+	for (uint32 i = 0; i < pagesTransferred; i++) {
+		fPages[i]->state = PAGE_STATE_ACTIVE;
+		fBusyConditions[i].Unpublish();
+	}
+
+	// Free pages after failed I/O
+	for (uint32 i = pagesTransferred; i < fPageCount; i++) {
+		fBusyConditions[i].Unpublish();
+		fCache->RemovePage(fPages[i]);
+		vm_page_set_state(fPages[i], PAGE_STATE_FREE);
+	}
+
+	delete this;
+}
+
+
+//	#pragma mark -
+
+
 static void
-add_to_iovec(iovec *vecs, int32 &index, int32 max, addr_t address, size_t size)
+add_to_iovec(iovec *vecs, uint32 &index, uint32 max, addr_t address,
+	size_t size)
 {
 	if (index > 0 && (addr_t)vecs[index - 1].iov_base
 			+ vecs[index - 1].iov_len == address) {
@@ -194,7 +332,7 @@ read_into_cache(file_cache_ref *ref, void *cookie, off_t offset,
 	// TODO: We're using way too much stack! Rather allocate a sufficiently
 	// large chunk on the heap.
 	iovec vecs[MAX_IO_VECS];
-	int32 vecCount = 0;
+	uint32 vecCount = 0;
 
 	size_t numBytes = PAGE_ALIGN(pageOffset + bufferSize);
 	vm_page *pages[MAX_IO_VECS];
@@ -314,7 +452,7 @@ write_to_cache(file_cache_ref *ref, void *cookie, off_t offset,
 	// TODO: We're using way too much stack! Rather allocate a sufficiently
 	// large chunk on the heap.
 	iovec vecs[MAX_IO_VECS];
-	int32 vecCount = 0;
+	uint32 vecCount = 0;
 	size_t numBytes = PAGE_ALIGN(pageOffset + bufferSize);
 	vm_page *pages[MAX_IO_VECS];
 	int32 pageIndex = 0;
@@ -391,7 +529,7 @@ write_to_cache(file_cache_ref *ref, void *cookie, off_t offset,
 		}
 	}
 
-	for (int32 i = 0; i < vecCount; i++) {
+	for (uint32 i = 0; i < vecCount; i++) {
 		addr_t base = (addr_t)vecs[i].iov_base;
 		size_t bytes = min_c(bufferSize,
 			size_t(vecs[i].iov_len - pageOffset));
@@ -757,6 +895,11 @@ file_cache_control(const char *subsystem, uint32 function, void *buffer,
 extern "C" void
 cache_prefetch_vnode(struct vnode *vnode, off_t offset, size_t size)
 {
+	if (low_resource_state(B_KERNEL_RESOURCE_PAGES) != B_NO_LOW_RESOURCE) {
+		// don't do anything if we don't have the resources left
+		return;
+	}
+
 	vm_cache *cache;
 	if (vfs_get_vnode_cache(vnode, &cache, false) != B_OK)
 		return;
@@ -764,16 +907,56 @@ cache_prefetch_vnode(struct vnode *vnode, off_t offset, size_t size)
 	file_cache_ref *ref = ((VMVnodeCache*)cache)->FileCacheRef();
 	off_t fileSize = cache->virtual_end;
 
-	if (size > fileSize)
+	if (offset >= fileSize) {
-		size = fileSize;
+		cache->ReleaseRef();
+		return;
+	}
+	if (offset + size > fileSize)
+		size = offset - fileSize;
 
-	// we never fetch more than 4 MB at once
+	// "offset" and "size" are always aligned to B_PAGE_SIZE,
-	if (size > 4 * 1024 * 1024)
+	offset &= ~(B_PAGE_SIZE - 1);
-		size = 4 * 1024 * 1024;
+	size = ROUNDUP(size, B_PAGE_SIZE);
 
-	cache_io(ref, NULL, offset, 0, &size, false);
+	size_t bytesToRead = 0;
-	cache->Lock();
+	off_t lastOffset = offset;
-	cache->ReleaseRefAndUnlock();
+
+	AutoLocker<VMCache> locker(cache);
+
+	while (true) {
+		// check if this page is already in memory
+		if (size > 0) {
+			vm_page* page = cache->LookupPage(offset);
+
+			offset += B_PAGE_SIZE;
+			size -= B_PAGE_SIZE;
+
+			if (page == NULL) {
+				bytesToRead += B_PAGE_SIZE;
+				continue;
+			}
+		}
+		if (bytesToRead != 0) {
+			// read the part before the current page (or the end of the request)
+			PrecacheIO* io
+				= new(std::nothrow) PrecacheIO(ref, lastOffset, bytesToRead);
+			if (io == NULL || io->Init() != B_OK || io->Start() != B_OK) {
+				delete io;
+				return;
+			}
+
+			bytesToRead = 0;
+		}
+
+		if (size == 0) {
+			// we have reached the end of the request
+			break;
+		}
+
+		lastOffset = offset + B_PAGE_SIZE;
+	}
+
+	cache->ReleaseRefLocked();
 }
 
 

src/system/kernel/fs/vfs_request_io.cpp

@@ -426,6 +426,32 @@ vfs_synchronous_io(io_request* request,
 }
 
 
+status_t
+vfs_asynchronous_read_pages(struct vnode* vnode, void* cookie, off_t pos,
+	const iovec* vecs, size_t count, size_t numBytes, uint32 flags,
+	AsyncIOCallback* callback)
+{
+	IORequest* request = IORequest::Create((flags & B_VIP_IO_REQUEST) != 0);
+	if (request == NULL) {
+		callback->IOFinished(B_NO_MEMORY, true, 0);
+		return B_NO_MEMORY;
+	}
+
+	status_t status = request->Init(pos, vecs, count, numBytes, false,
+		flags | B_DELETE_IO_REQUEST);
+	if (status != B_OK) {
+		delete request;
+		callback->IOFinished(status, true, 0);
+		return status;
+	}
+
+	request->SetFinishedCallback(&AsyncIOCallback::IORequestCallback,
+		callback);
+
+	return vfs_vnode_io(vnode, cookie, request);
+}
+
+
 status_t
 vfs_asynchronous_write_pages(struct vnode* vnode, void* cookie, off_t pos,
 	const iovec* vecs, size_t count, size_t numBytes, uint32 flags,

src/system/kernel/vm/vm.cpp

@@ -2256,9 +2256,9 @@ pre_map_area_pages(vm_area* area, VMCache* cache)
 	\a offset and \a size arguments have to be page aligned.
 */
 static area_id
-_vm_map_file(team_id team, const char* name, void** _address, uint32 addressSpec,
+_vm_map_file(team_id team, const char* name, void** _address,
-	size_t size, uint32 protection, uint32 mapping, int fd, off_t offset,
+	uint32 addressSpec, size_t size, uint32 protection, uint32 mapping, int fd,
-	bool kernel)
+	off_t offset, bool kernel)
 {
 	// TODO: for binary files, we want to make sure that they get the
 	//	copy of a file at a given time, ie. later changes should not
@@ -2352,7 +2352,7 @@ _vm_map_file(team_id team, const char* name, void** _address, uint32 addressSpec
 		offset, size, addressSpec, 0, protection, mapping, &area, name,
 		addressSpec == B_EXACT_ADDRESS, kernel);
 
-	if (status < B_OK || mapping == REGION_PRIVATE_MAP) {
+	if (status != B_OK || mapping == REGION_PRIVATE_MAP) {
 		// map_backing_store() cannot know we no longer need the ref
 		cache->ReleaseRefLocked();
 	}
@@ -2362,7 +2362,14 @@ _vm_map_file(team_id team, const char* name, void** _address, uint32 addressSpec
 
 	cache->Unlock();
 
-	if (status < B_OK)
+	if (status == B_OK) {
+		// TODO: this probably deserves a smarter solution, ie. don't always
+		// prefetch stuff
+		cache_prefetch_vnode(vnode, offset, min_c(size, 10LL * 1024 * 1024));
+			// prefetches at max 10 MB starting from "offset"
+	}
+
+	if (status != B_OK)
 		return status;
 
 	area->cache_type = CACHE_TYPE_VNODE;