Windows® Internals, Sixth Edition, Part 1

One of the key issues with multiprocessor systems is scalability. To run correctly on an SMP system, operating system code must adhere to strict guidelines and rules. Resource contention and other performance issues are more complicated in multiprocessing systems than in uniprocessor systems and must be accounted for in the system’s design. Windows incorporates several features that are crucial to its success as a multiprocessor operating system:

The ability to run operating system code on any available processor and on multiple processors at the same time

Multiple threads of execution within a single process, each of which can execute simultaneously on different processors

Fine-grained synchronization within the kernel (such as spinlocks, queued spinlocks, and pushlocks, described in Chapter 3) as well as within device drivers and server processes, which allows more components to run concurrently on multiple processors

Programming mechanisms such as I/O completion ports (described in Chapter 8, “I/O System,” in Part 2) that facilitate the efficient implementation of multithreaded server processes that can scale well on multiprocessor systems

The scalability of the Windows kernel has evolved over time. For example, Windows Server 2003 introduced per-CPU scheduling queues, which permit thread scheduling decisions to occur in parallel on multiple processors. Windows 7 and Windows Server 2008 R2 eliminated global locking on the scheduling database. This step-wise improvement of the granularity of locking has also occurred in other areas, such as the memory manager. Further details on multiprocessor synchronization can be found in Chapter 3.

Differences Between Client and Server Versions

Windows ships in both client and server retail packages. As of this writing, there are six client versions of Windows 7: Windows 7 Home Basic, Windows 7 Home Premium, Windows 7 Professional, Windows 7 Ultimate, Windows 7 Enterprise, and Windows 7 Starter.

There are seven different versions of Windows Server 2008 R2: Windows Server 2008 R2 Foundation, Windows Server 2008 R2 Standard, Windows Server 2008 R2 Enterprise, Windows Server 2008 R2 Datacenter, Windows Web Server 2008 R2, Windows HPC Server 2008 R2, and Windows Server 2008 R2 for Itanium-Based Systems (which is the last release of Windows to support the Intel Itanium processor).

Additionally, there are “N” versions of the client that do not include Windows Media Player. Finally, the Standard, Enterprise, and Datacenter editions of Windows Server 2008 R2 also include “with Hyper-V” editions, which include Hyper-V. (Hyper-V virtualization is discussed in Chapter 3.)

These versions differ by

The number of processors supported (in terms of sockets, not cores or threads)

The amount of physical memory supported (actually highest physical address usable for RAM—see Chapter 10 in Part 2 for more information on physical memory limits)

The number of concurrent network connections supported (For example, a maximum of 10 concurrent connections are allowed to the file and print services in the client version.)

Support for Media Center

Support for Multi-Touch, Aero, and Desktop Compositing

Support for features such as BitLocker, VHD Booting, AppLocker, Windows XP Compatibility Mode, and more than 100 other configurable licensing policy values

Layered services that come with Windows Server editions that don’t come with the client editions (for example, directory services and clustering)

Table 2-2 lists the differences in memory and processor support for Windows 7 and Windows Server 2008 R2. For a detailed comparison chart of the different editions of Windows Server 2008 R2, see www.microsoft.com/windowsserver2008/en/us/r2-compare-specs.aspx.

Table 2-2. Differences Between Windows 7 and Windows Server 2008 R2

 

Number of Sockets Supported (32-Bit Edition)

Physical Memory Supported (32-Bit Edition)

Number of Sockets Supported (64-Bit Edition)

Physical Memory Supported (Itanium Editions)

Physical Memory Supported (x64 Editions)

Windows 7 Starter

1

2 GB

Not available

Not available

2 GB

Windows 7 Home Basic

1

4 GB

1

Not available

8 GB

Windows 7 Home Premium

1

4 GB

1

Not available

16 GB

Windows 7 Professional

2

4 GB

2

Not available

192 GB

Windows 7 Enterprise

2

4 GB

2

Not available

192 GB

Windows 7 Ultimate

2

4 GB

2

Not available

192 GB

Windows Server 2008 R2 Foundation

Not available

Not available

1

Not available

8 GB

Windows Web Server 2008 R2

Not available

Not available

4

Not available

32 GB

Windows Server 2008 R2 Standard

Not available

Not available

4

Not available

32 GB

Windows HPC Server 2008 R2

Not available

Not available

4

Not available

128 GB

Windows Server 2008 R2 Enterprise