Sunday, 25 November 2012

Under the hood of Windows 8, or why desktop users should upgrade from Windows 7


Windows 8 has been out for a while — the result of more than three years of work by one of the world’s largest cross-disciplinary software and hardware engineering teams, and undoubtedly the largest, most daring, and most vital project the Redmond, Washington company has ever attempted.
Under the hood of Windows 8, or why desktop users should upgrade from Windows 7
At this point, if you’re a desktop or laptop user, you are probably laughing in my face. “Microsoft spent three years killing the Start menu and introducing a new tablet interface,” you say. “Windows 8 is Windows 7 with a cross-paradigm UI/UX trainwreck,” you bellow — and to an extent, you are correct. Windows 8 is undoubtedly a tablet-oriented operating system. Microsoft has tried to pass it off as a “touch-first OS,” but that’s just euphemistic swill from the PR department.
Given the way Microsoft seems to be spending most of its $1.5 billion Windows 8 marketing budget on the Surface tablet and the Metro Start screen, you would be forgiven for thinking that the Desktop (Explorer) side of things has simply been swept under the rug. You would be even be forgiven for thinking that Microsoft has abandoned the existing two billion users of the Windows Desktop, opting instead to recklessly chase the shiny, happy, and unproven tablet market.
Thankfully, though, Windows 7 isn’t the end of the Desktop line. Windows 8 does actually include a ton of tweaks and upgrades that Desktop users will very much enjoy. I’ve been using Windows 8 for a year now, and I can definitely say that the Desktop experience is faster, and generally better than Windows 7. Enough talking, though; let’s actually dive on in and take a closer look at the Windows 8 underbelly.
Core upgrades
By designing Windows 8 for tablets, Microsoft was forced to put a lot of effort into streamlining the entire OS for battery-powered, wimpy (Atom and ARM) mobile devices. As a result, Windows 8 boots up faster, and the OS itself consumes less RAM and CPU cycles than Windows 7. For mobile users this means more battery life and snappier performance — but for Desktop users, this means Windows 8 is simply faster than Windows 7.
Let’s break it down.
Startup
The very first thing you’ll notice with Windows 8 is that it boots a lot faster than Windows 7 (or Vista or XP, if you’re still part of the significant minority hanging onto either). This is partly because of the shift to UEFI (from BIOS), but primarily because of a clever tweak to the boot process. If you’re still using a mechanical hard drive, your boot time will probably go from around 30 seconds to 15-20 seconds. If you’re using an SSD, boot generally takes less than 10 seconds.
Basically, when you shut down a Windows 7 (or any other kind of PC), the slate is wiped clean. When you shut down Windows 8, the low-level system state (kernel/session 0) is saved to your hard drive, just like hibernation. Then, when you boot, only drivers need to be reinitialized — which is a lot faster than loading up the entire operating system. It’s kind of a cheat, but it works very well.
Incidentally, if you want to perform a full “cold” boot (without the kernel being hibernated), simply select Restart from the shutdown menu or run shutdown /s /full /t 0.
Security
While exact details of the Windows 8 kernel are fairly hard to come by, we do know that a lot of changes were made to ruggedize Windows 8 against malware and rootkits. For the most part, these protections take the form of memory allocation safeguards (see below).
Many hackers have already gone on the record to say that Windows 8 is (and will be) very hard to break into.
Due to the inclusion of UEFI (which is basically like a very light-weight operating system that then loads Windows), there is also a boot-level malware scanner that will prevent your computer from booting if a USB thumb drive is infected. There’s also Secure Boot, which stops the system from loading if any core system files have been altered.
Power management
Improved power management in Windows 8 takes a three-pronged approach: The introduction of the Metro app model; idle hygiene; and runtime device power management.
In Windows 8, Metro apps run on top of a new application architecture called WinRT, which is a low-level set of APIs that run just above the Windows kernel. WinRT is the Metro equivalent of Win32, which is the API that Desktop apps use. WinRT, because it is ultimately targeted towards tablet (and eventually smartphone) apps, is designed from the outset to be power efficient. In general, Metro apps are very good at only running when they need to run — otherwise, they are very quickly shifted to a suspended state, to minimize their CPU use, and thus power use. To cater for apps that need to periodically update for freshness, such as news or email apps, WinRT also includes functions for doing this efficiently (called Background Tasks).
Idle hygiene and runtime device power management will both result in slightly better battery life (and performance) for Windows 8 laptop and desktop users, though. Idle hygiene is basically what it sounds like: It’s the trick of getting the CPU back to an idle, low-power state as soon as possible. In recent years, most chip makers (x86 and ARM) have made big strides towards CPUs that shut down unused parts of the chip. In simple terms, an Intel chip might have four cores — but a lot of power can be saved if three of those are fully turned off when they’re not needed. In Windows 8, improved idle hygiene should result in less power usage, and also more CPU time for apps that need it.
Runtime device power management is basically the same thing as idle hygiene, but for other hardware — such as hard drives, wireless radios, and so on. Without active power management, these devices can consume huge amounts of power.
Higher level
Combined, Windows 8′s low-level changes should result in an OS that is faster, more secure, and lasts longer on battery power. Moving up the stack, though, the desktop side of Windows 8 has a ton of upgrades and much-needed tweaks, too. Out of the box, Windows 8 will be a lot more functional than Windows 7.

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