Newsgroup: it.comp.os.win.xp
Titolo: Il sistema si raddrizza col tempo?

Ho notato una cosa curiosa, da quando ho Windows XP.
All'inizio, tre mesi fa, osservavo due bug abbastanza gravi.
Uno in chiusura: Explorer rimaneva bloccato e compariva la finestra che mi
dava la possibilita' di terminarne forzatamente l'esecuzione (roba da
Windows 95!).
L'altro, invece, era dovuto al servizio svchost.exe che ogni tanto, in
seguito a non precisate condizioni, arrivava ad occupare il 100% della CPU.
Ora questi bug mi sono spariti... un fenomeno davvero curioso, in genere un
sistema operativo tende a deteriorarsi a forza di "pasticciamenti", non il
contrario...
Delle due l'una:
1) Windows XP ha sofisticati fattori di auto-correzione, che portano il
sistema a perfezionarsi nel tempo "imparando" dai bug avvenuti
2) Quegli innumerevoli aggiornamenti di Windowsupdate servono davvero a
qualcosa
...delle 2 non so quale sia la piu' assurda! :)

La terza di sicuro:
si autoformatterà reinstallando il sistema senza bisogno dell'utente! :-P

La seconda che hai detto... sono le patch è l'assuefazione dell'hardware a
winzozz!
--
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
 Per rispondermi togliete -NOSPAM- !!!!
  => 
anghelio...@virgilio.it
 <=
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
  La ragione e la sapienza parlano,
      il torto e l'ignoranza urlano. (Graf)
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

      Microsoft® Windows XP offers excellent overall performance-in part
because it dynamically adjusts itself based upon individual use.
      This article addresses some of the dynamic tuning capabilities of
Windows XP, and outlines steps you should take in order to get consistent
benchmark results. It provides information on how to avoid System Restore
checkpoint activity during benchmark runs.
      Introduction
      The Windows XP operating system achieves excellent performance in part
by dynamic adjustments that it makes in response to how a system is
utilized. In particular, many adjustments are made when the system first
runs following setup and when newly installed applications are used for the
first time. These adjustments greatly influence the performance of the
system. Unfortunately, the dynamic nature of Windows XP can make
benchmarking more of challenge than with previous Windows versions.
      The purpose of this article is to familiarize the reader with the
dynamic tuning done on Windows XP, to explain why performance on Day 3 after
installing the system and applications may be better than on Day 1, and to
outline a testing methodology that is both representative of what real
customers will experience and capable of producing consistent results from
benchmark run to benchmark run.
      General Concepts: The Dynamic Nature of Windows XP
      Windows XP is a dynamic, self-tuning operating system, and has
built-in features that support this both at setup and during continued use.
As a consequence, the system's performance after having the opportunity to
tune itself will be different from its performance when it boots up for the
first time or when it executes a particular application for the first time.
      Operating System Setup
      There are two types of dynamic adjustments made during the setup of
Windows XP: RAM-based adjustments and video-based adjustments. The RAM-based
adjustments are simple; if the system has 64MB of physical memory during
setup, then:
        a.. No background bit map will used by default
        b.. Fast user switching will be off by default
      The video-based adjustments are determined by running a variety of
atomic tests after the video resolution and color depth have been
automatically determined. If a specific atomic test takes too long to
complete, then the corresponding visual effect is turned off by default.
Microsoft added the visual-based adjustments to ensure a responsive user
experience with the new user interface and visuals. The majority of systems
will have all of the visuals on by default; a few systems with video driver
or video adapter performance issues will be configured with the effects off
by default.
      The following effects are dynamically configured during setup:
        a.. Slide taskbar buttons
        b.. Use drop shadows for icon labels on the desktop
        c.. Smooth edges of screen fonts
        d.. Fade or slide menus into view
        e.. Fade out menu items after clicking
        f.. Fade or slide ToolTips into view
        g.. Show shadows under menus
        h.. Show translucent selection rectangle
        i.. These visual effects and others can have dramatic impact on
benchmark scores.
      Although Microsoft strongly recommends using the defaults because that
is what most users will use, the configuring of visual effects settings can
be done quite easily on Windows XP. To display the full list of easily
configurable visual effects settings, right-click My Computer, select
Properties, select the Advanced tab, and select the Settings button under
Performance. The Performance Options dialog box is shown below in Figure 1.
      Figure 1: Performance Options dialog box used to manually configure
visual effects.
      Click to view full-size image.
      Return...
      Disk Efficiency Optimizations
      The physical placement, or layout, of files on the disk can have a
considerable effect on performance, up to 10% for normal use. Windows XP
observes file usage patterns as the system is used. If deemed necessary,
Windows XP will adjust the file layout at three day intervals. By placing
files that are referenced together near each other on the disk, and towards
the more dense outer edge of the disk, seek distances are reduced which
results in shorter seek times and improved performance. The performance
benefit of placing files becomes increasing important as the size of the
disk increases.
      The files moved for more efficient layout are also kept contiguous.
Windows XP does not intentionally fragment files as was done by some earlier
versions of Windows.
      Even though the disk layout optimization does insure some files will
be defragmented, it is not a complete substitute for fully defragmenting the
disk. Users should still defragment their drives regularly. The built-in
Windows XP defragmentation program understands the file layout directives
and will position the files if they aren't already placed properly. However,
it will not update the layout file with new information gathered in the last
three days. Without manual intervention, the layout file,
%windir%\Prefetch\Layout.ini, will only be updated once every three days.
The contents of the Layout.ini file can be viewed with Notepad.
      Boot Prefetching
      Windows XP speeds up system boot by observing the code and data needed
each time the system is booted and prefetching the necessary file contents
early in the boot process. This prefetching is not done until the third boot
of the system, when sufficient information is available to make the
prefetching most effective. The files observed during system boot will be
used in the disk layout process mentioned above. Additional information on
the prefetcher and the Windows XP boot process can be found at Fast
Boot/Fast Resume for the Windows Platform.
      Application-Launch Prefetching
      Windows XP also uses prefetching when launching applications. The
files and the contents of the files accessed by each new process are
observed and recorded. No prefetching can be done for the first launch of an
application, so first launches are often considerably slower than subsequent
launches. About 85% to 90% of the improvement is realized after just one
launch of an application, with the remaining speed improvement coming after
the system has had an opportunity to adjust the disk layout with information
specific to this application.
      Benchmarking on a Dynamic and Self-Tuning Windows XP
      Benchmarking an operating system that is attempting to improve itself
over time based upon observed usage patterns can be difficult. It becomes
ever more difficult to benchmark if the operating system is also attempting
to create dynamic system restore points when large amounts of applications
are installed. Fortunately, there is a methodology that provides consistent
results, accurately reflects the performance that Windows XP systems will
achieve, and is fairly easy to follow.
      The basics of the methodology are:
        a.. Install
        Install the OS and benchmark as normal.
        b.. Use
        Run the benchmark one or more times.
        OR
        Use the applications in the benchmark as real users would.
        c.. Let Idle Tasks Run
        Leave the system for a bit after using it, (up to three days for
disk layout optimizations).
        OR
        Call the ProcessIdleTask API from advapi32.dll.
        d.. Test
        Run the benchmark as usual.
      Idle Task Scheduling: The ProcessIdleTask API
      The file placement optimization, which is done no more often than once
every three days, is an example of a task that is carried out when the
system is deemed to be idle. System Restore and other features of Windows XP
also attempt to defer some work until the system is deemed to be idle. There
are also some done-once-after-setup work items that also operate under the
Idle Task Scheduling mechanisms.
      All of these "idle tasks" are controllable by a system API in
advapi32.dll, ProcessIdleTasks. The API's sole purpose is to allow
benchmarks a simple way to force any pending idle tasks to be executed
immediately, without having to wait a lengthy period of time.
      The API ProcessIdleTasks can be called in one of two ways, from the
command line or synchronously from a program.  To call ProcessIdleTasks from
the command line, use this syntax:
Rundll32.exe advapi32.dll,ProcessIdleTasks
      When called from the command line, the ProcessIdleTasks work is done
in the background asynchronously. It can take 10 to 15 minutes for idle
tasks to complete. Task Manager will report processes running, and the disk
will likely be active during this time.
      The ProcessIdleTasks API takes no arguments and returns a standard
Win32 error code. The definition is:
DWORD
ProcessIdleTasks()
      The API itself is synchronous, so it won't return until the idle tasks
have completed.
      Other Testing Issues
      Clean Installation Preferred
      When benchmarking Windows XP, Microsoft strongly recommends a clean
installation using NTFS. There are several reasons why performance for a
clean installation will tend to be superior to that for upgraded systems. An
upgraded system will constrain the placement of files and file system data.
The old disk format may not use an optimal file system cluster size. In a
clean installation, the placement of file system data on the disk and the
internal organization of that data can be optimized, resulting in a smaller
system footprint and fewer and faster I/Os when using the system.
      When performing a clean install, Microsoft recommends that NTFS be
used and that the system be installed in a single partition on each disk.
Under Windows XP, big partitions are better managed than in previous
versions of Windows. Forcing installed software into several partitions on
the disk necessitates longer seeks when running the system and software.
      If you do choose an upgrade from Windows 2000 or Windows 9x, you may
be working with a FAT32 file system. Performance will generally be better if
the file system is left as it is, rather than converted to NTFS. A partition
converted from FAT32 to NTFS may have to use 512-byte clusters, rather than
4096-byte or 8192-byte clusters, which can result in a higher number of
fragmented files.
      Installation in 64 MB Differs from Installation in 128 MB
      Windows XP determines at setup time which, if any, operating system
features will be turned off by default. In 64 MB there will be no background
bitmap on the desktop and Fast User Switching will be disabled by default.
Thus, an installation in 128 MB or more which is then restricted to using 64
MB of memory (for example by setting the MAXMEM option in boot.ini) will
behave differently than would a proper installation in 64 MB.
      First and Second Boots Following Installation
      As noted in the previous section, Windows XP fast boot only begins to
operate on the third boot following installation. For the first boot there
is simply no information available that would indicate what code or data
needs to be prefetched. The first boot, moreover, must perform a large
number of initialization and other one-time-only tasks. Consequently, using
information about this boot as a template for subsequent boots would be a
mistake. It is this second boot, therefore, that is observed and information
about this boot is used for subsequent prefetching and disk layout
optimizations. By the third boot, appropriate information is available that
will greatly improve boot speed. Microsoft has found that about 90% of the
speed improvement in boot will occur for the third boot, with the remaining
10% coming after the system has had a chance to lay out the files to improve
disk efficiency.
      Windows Activation and Windows Update
      Microsoft recommends that you activate your Windows XP installation
before using it to measure performance, because the activation detection
will impose a slight cost on the system at some times and no cost at other
times. The variability is the issue. Also, because users need to activate
within a short period of time after installation, the vast majority of
system use will be done after activation, which makes measurements taken
after activation more realistic.
      Note that you can still create master images that have indefinite
shelf life using standard RTM product keys (but not for MSDN keys or
evaluation keys/media). This is accomplished by installing the image master
with any standard retail key. The master should not be activated. As the
final step prior to shutdown, run sysprep (available on the distribution
media from the Support\Tools folder in Deploy.cab). This will reset the
activation logic to provide indefinite storage prior to imaging and the full
30-day activation grace period for clones. Sysprep will reset the activation
grace period on any master or derivative up to three times.
      Because activating large numbers of machines can be undesirable, you
might want to run most of your benchmarks on unactivated systems and reserve
your activation tests for the final round, or in cases where you are
concerned that activation might be a problem. If you must activate large
numbers of machines, the draft WPA Deployment white paper available on the
Windows Beta web site might provide some useful advice.
      Similarly, Windows Updates should either be applied or disabled so
that the system will not try to check whether updates are available in the
middle of benchmark runs. Microsoft believes most consumers will apply the
updates so it is best to apply the updates before testing.
      Video Resolution
      The video resolution chosen for the system will have a strong impact
upon the sizes of bitmaps and other data structure in the kernel. If the
graphics subsystem can support it, the default pixel color depth for Windows
XP is 32 bits per pixel. If you are comparing Windows XP with a different
version of Windows, it is important to ensure that the color depth for the
two systems is matched. It is also best to try to use the same drivers for
both, using the most recent versions of drivers from the web, or to take the
default, inbox drivers for each system and compare default to default.
      Summary
      Windows XP can deliver excellent performance, but because it is more
sophisticated than previous versions of Windows, care must be taken to
obtain valid results. Understanding the issues described in this article can
help you arrive at better benchmarking practices and save time and effort
      For More Information
      For the latest information on Windows XP, check out the Windows XP
home page.
      To learn more about how Microsoft and its OEM partners are working to
improve boot and resume times, see Fast Boot/Fast Resume for the Windows
Platform.
      About this Paper   Printer Version
      Last Updated: December 4, 2001