This isn't a bad article. The most interesting part for me was the following comment ""The top compatibility issue when a new version of Windows comes out is drivers checking for a very specific version."

In other words, many drivers say "if this doesn't equal Windows XP, then don't install", even though they might work perfectly well on later releases. Angiulo recommends ignoring those kinds of checks: "Trust us to do that compatibility." "


How does Windows 7 improve performance?

"We believe we can get below 1% idle CPU utilisation with Windows 7." What technical tricks is Microsoft using to try and get the next release of Windows to those levels?

Early reviews of the Windows 7 M3 release have generally agreed on one point: the speed is surprisingly good. It turns out Windows 7 runs quite healthily, especially given that it is still a pre-beta release and that it's largely based on Vista, which doesn't have much of a reputation for efficiency.

Some of that improved performance is probably due to what's missing. The M3 code is API-complete but doesn't include many of the user interface elements that will appear in the final release. M3 doesn't do any serious checking on whether the product is official or not (a situation which has led to extensive torrent exchanges of the code), something that's bound to be addressed with some cycle-hogging Windows Genuine Advantage tweaking before the official commercial release.

But despite those potential roadblocks, improved performance and power efficiency remains a major goal for Windows 7. Indeed, getting the system to not consume resources when no major tasks are being performed is just as much a focus as running existing applications efficiently. "We believe we can get below 1% idle CPU utilisation with Windows 7," Microsoft windows PC ecosystem and planning team lead Mike Angiulo remarked at last week's WinHEC conference in Los Angeles. But just how can that be done?
Startup tweaks

One of Microsoft's specific goals for Windows 7 was to improve on Vista's sluggish boot times. A big part of that improvement comes from the way in which drivers are handled. Rather than loading device drivers one after another, which was the approach for Vista, Windows 7 loads device drivers in parallel, which can potentially make a huge difference. (The assumption here is that drivers are well-coded — a poorly-written driver could easily bring the whole start-up process to its knees.)

A second major improvement is that rather than pre-loading a large number of services which may or may not be needed (depending on your specific configuration), Windows 7 only loads a small core group of services, and then accesses others only when needed. By lowering the number of services that start, we can deliver a superior start-up experience," Angiulo said.

A similar approach is being used with the Windows shutdown experience. The all-too-familiar experience of Vista sitting on the shutdown screen for minutes at a time, or not even exiting it at all, can usually be traced to a single service which has failed to exit gracefully, Angiulo said. "It tells us there's some kind of an untied shoelace that we can go in and fix."

For all that, Microsoft continues to measure boot times not by the real-world measure of when you can actually get anything done, but by the slightly more artificial number of when the initial loading screen appears. In part, that's because there's no accurate way of knowing what other programs might be loaded at startup (though some sort of security software could presumably be a given). Angiulo is the first to admit that the final figure will depend on other ISVs as well as the core code: "This is an important scenario that we're really all working on together."

The same argument applies to reducing idle performance, which helps extend battery life and reduce overall power consumption. While Windows 7 can try to minimise consumption in those areas, badlyt-written drivers can easily consume unneeded cycles.
Hardware and horrors

Another major emphasis in Windows 7 is on making use of the high-powered hardware that's increasingly common on all but the cheapest of PCs. During WinHEC's opening, Angiulo ran a demo showing how Windows 7 could handle many more simultaneous application windows being opened than Vista, because memory management is now independent of the window count, and the graphical detail is handled by graphics cards rather than entirely by the OS.

Again, though, such tweaks are largely dependent on hardware manufacturers coming to the party and writing well-behaved drivers. (Documents which emerged during the post-Vista 'compatible' debacle suggested that a large percentage of crashes could be blamed on poor Nvidia drivers.) Angiulo identified one particular problem: "The top compatibility issue when a new version of Windows comes out is drivers checking for a very specific version."

In other words, many drivers say "if this doesn't equal Windows XP, then don't install", even though they might work perfectly well on later releases. Angiulo recommends ignoring those kinds of checks: "Trust us to do that compatibility." "

http://apcmag.com/how_does_windows_7...erformance.htm

Posted By: NormCameron
12 Nov 2008