Implemented the basic I/O scheduler architecture - doesn't schedule anything

yet, though (instead, it directly performs all requests, so there is no
functional difference to the previous mechanism).
devfs and the file cache will directly access the I/O scheduler. There is
one scheduler per raw disk device; devfs detects that automatically, and
all I/O will go through the scheduler, then.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@8683 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kernel/core/fs/IOScheduler.cpp

@@ -0,0 +1,116 @@
+/* 
+** Copyright 2004, Axel Dörfler, [email protected]. All rights reserved.
+** Distributed under the terms of the Haiku License.
+*/
+
+
+#include "IOScheduler.h"
+
+#include <KernelExport.h>
+
+#include <khash.h>
+#include <lock.h>
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+IORequest::IORequest(void *_cookie, off_t _offset, void *_buffer, size_t _size, bool _writeMode)
+	:
+	cookie(_cookie),
+	virtual_address(addr_t(_buffer)),
+	offset(_offset),
+	size(_size),
+	write(_writeMode)
+{
+}
+
+
+IORequest::IORequest(void *_cookie, off_t _offset, const void *_buffer, size_t _size, bool _writeMode)
+	:
+	cookie(_cookie),
+	virtual_address(addr_t(const_cast<void *>(_buffer))),
+	offset(_offset),
+	size(_size),
+	write(_writeMode)
+{
+}
+
+
+//	#pragma mark -
+
+
+IOScheduler::IOScheduler(const char *name, device_hooks *hooks)
+	:
+	fDeviceHooks(hooks)
+{
+	mutex_init(&fLock, "I/O scheduler queue");
+
+	// start thread for device
+	fThread = spawn_kernel_thread(&IOScheduler::scheduler, name, B_NORMAL_PRIORITY, (void *)this);
+#if 0
+	if (fThread >= B_OK)
+		resume_thread(fThread);
+#endif
+}
+
+
+IOScheduler::~IOScheduler()
+{
+	kill_thread(fThread);
+	mutex_destroy(&fLock);
+}
+
+
+status_t
+IOScheduler::InitCheck() const
+{
+	if (fLock.sem < B_OK)
+		return fLock.sem;
+
+	if (fThread < B_OK)
+		return fThread;
+
+	return B_OK;
+}
+
+
+status_t
+IOScheduler::Process(IORequest &request)
+{
+	// ToDo: put the request into the queue, and wait until it got processed by the scheduler
+	// ToDo: translate addresses into physical locations
+	// ToDo: connect to the DPC mechanism in the SCSI/IDE bus manager?
+	// ToDo: assume locked memory?
+
+	if (request.write)
+		return fDeviceHooks->write(request.cookie, request.offset, (const void *)request.virtual_address, &request.size);
+
+	return fDeviceHooks->read(request.cookie, request.offset, (void *)request.virtual_address, &request.size);
+}
+
+
+#if 0
+IOScheduler *
+IOScheduler::GetScheduler()
+{
+	return NULL;
+}
+#endif
+
+
+int32
+IOScheduler::Scheduler()
+{
+	// main loop
+}
+
+
+int32
+IOScheduler::scheduler(void *_self)
+{
+	IOScheduler *self = (IOScheduler *)_self;
+	return self->Scheduler();
+}
+

src/kernel/core/fs/IOScheduler.h

@@ -0,0 +1,59 @@
+/*
+** Copyright 2004, Axel Dörfler, [email protected]. All rights reserved.
+** Distributed under the terms of the Haiku License.
+*/
+#ifndef IO_SCHEDULER_H
+#define IO_SCHEDULER_H
+
+
+#include <OS.h>
+#include <Drivers.h>
+
+#include <util/DoublyLinkedList.h>
+#include <lock.h>
+
+
+class IORequest {
+	public:
+		IORequest(void *cookie, off_t offset, void *buffer, size_t size, bool write = false);
+		IORequest(void *cookie, off_t offset, const void *buffer, size_t size, bool write = true);
+			// ToDo: iovecs version?
+
+		size_t Size() const { return size; }
+
+		DoublyLinked::Link link;
+
+		void		*cookie;
+		addr_t		physical_address;
+		addr_t		virtual_address;
+		off_t		offset;
+		size_t		size;
+		bool		write;
+		thread_id	thread;
+};
+
+
+class IOScheduler {
+	public:
+		IOScheduler(const char *name, device_hooks *hooks);
+		~IOScheduler();
+
+		status_t InitCheck() const;
+		status_t Process(IORequest &request);
+
+#if 0
+		static IOScheduler *GetScheduler();
+#endif
+
+	private:
+		int32 Scheduler();
+		static int32 scheduler(void *);
+
+	private:
+		device_hooks	*fDeviceHooks;
+		mutex			fLock;
+		thread_id		fThread;
+		DoublyLinked::List<IORequest, &IORequest::link> fRequests;
+};
+
+#endif	/* IO_SCHEDULER_H */