Difference between pages "Windows Registry" and "SuperFetch"

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==File Locations==
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{{Expand}}
The Windows Registry is stored in multiple files.
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===Windows NT 4 ===
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SuperFetch is a performance enhancement introduced in [[Microsoft]] [[Windows|Windows Vista]] to reduce the time necessary to launch applications. SuperFetch works with the memory manager service in Windows to analyze memory usage patterns over time to determine the optimal memory content for a given user for a date or time of day. This differs from the [[Prefetch]] technique used in Microsoft Windows XP, which preloads data into memory without analyzing usage patterns.
In Windows NT 4 (and later) the Registry is stored in the [[Windows NT Registry File (REGF)]] format.
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Basically the following Registry hives are stored in the corresponding files:
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From [http://msdn.microsoft.com/en-us/library/windows/hardware/dn653317(v=vs.85).aspx]: SuperFetch prioritizes the following kinds of pages to remain in memory:
* HKEY_USERS: \Documents and Setting\User Profile\NTUSER.DAT
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* Pages of applications that are used most frequently overall.  
* HKEY_USERS\DEFAULT: C:\Windows\system32\config\default
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* Pages of applications that are commonly used when resuming:  
* HKEY_LOCAL_MACHINE\SAM: C:\Windows\system32\config\SAM
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** After extensive hibernation (for example, first thing in the morning).
* HKEY_LOCAL_MACHINE\SECURITY: C:\Windows\system32\config\SECURITY
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** After shorter periods of sleep or hibernation (for example, after lunch).
* HKEY_LOCAL_MACHINE\SOFTWARE: C:\Windows\system32\config\software
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* HKEY_LOCAL_MACHINE\SYSTEM: C:\Windows\system32\config\system
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===Windows 98/ME===
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If SuperFetch detects that the system drive is a fast SSD (as measured by Windows Experience Index Disk score), then SuperFetch turns off [[ReadyBoot]], [[ReadyBoost]], and the SuperFetch service itself.
* \Windows\user.dat
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* \Windows\system.dat
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* \Windows\profiles\user profile\user.dat
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== Keys ==
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== Components ==
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=== Robust performance ===
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Robust performance (or robustness) is a component of SuperFetch to watch for specific file I/O access that might harm system performance by populating the standby lists with unneeded data.
  
=== Run/RunOnce ===
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== Scenarios ==
System-wide:
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SuperFetch distinguishes between different scenarios to accurately measure performance.
<pre>
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HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
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HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
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</pre>
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Per user:
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=== Cold scenario ===
<pre>
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In a cold scenario, the test applications are not already in memory when the test begins. Cold scenarios measure performance either after a state transition, such as boot or resume from hibernation, or after another application claims most of the available memory, such as after launching and quitting a game.
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
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HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
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</pre>
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== Special cases ==
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=== Warm scenario ===
The Windows Registry has several special case scenarios, mainly concerning key and value name, that are easy to fail to account for:
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In a warm scenario, some or all the scenario contents are in memory before measurement. This usually means that the test has run at least once during this logon session.
* special characters key and value names
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* duplicate key and value names
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* the names when stored in extended ASCII (ANSI string) use a codepage that is dependent on the system settings
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=== special characters key and value names ===
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== Configuration ==
Both key and values names are case insensitive. The \ character is used as the key separator. Note
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that the \ character can be used in value names. The / character is used in both key and value names.
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Some examples of which are:
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<pre>
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Key: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services\NetBT\Parameters\
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Value: Size/Small/Medium/Large
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</pre>
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Because SuperFetch appears to leave a system with no available memory, some users turn it off to create the appearance of having more free memory. The feature can be configured by changing the [[Registry]] value [http://www.codinghorror.com/blog/archives/000688.html]:
 
<pre>
 
<pre>
Key: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Terminal Server\VIDEO\disc\
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Key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters
Value: \Device\Video0
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Value: EnableSuperfetch
 
</pre>
 
</pre>
  
<pre>
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A value of zero disables SuperFetch, one enables it for booting only, two for applications, and three for both applications and boot. This setting can also be changed using the Services console, <tt>services.msc</tt> [http://tiredblogger.wordpress.com/2007/03/27/superfetch-not-so-super-for-gaming/].
Key:
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HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\services\xmlprov\Parameters\SchemaGroups\User\http://www.microsoft.com/provisioning/eaptlsuserpropertiesv1\
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Value: SchemaFile
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</pre>
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=== codepaged ASCII strings ===
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Value with name "ëigenaardig" created on Windows XP codepage 1252.
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<pre>
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value key data:
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00000000: 76 6b 0b 00 46 00 00 00  20 98 1a 00 01 00 00 00  vk..F...  .......
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00000010: 01 00 69 6e eb 69 67 65  6e 61 61 72 64 69 67 00  ..in.ige naardig.
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00000020: 55 4e 49 43                                        UNIC
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value key signature                    : vk
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value key value name size              : 11
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value key data size                    : 0x00000046 (70)
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value key data offset                  : 0x001a9820
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value key data type                    : 1 (REG_SZ) String
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value key flags                        : 0x0001
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        Value name is an ASCII string
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value key unknown1                      : 0x6e69 (28265)
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value key value name                    : ëigenaardig
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value key value name hash              : 0xb78835ee
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value key padding:
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00000000: 00 55 4e 49 43                                    .UNIC
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</pre>
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As you can see the name is stored in extended ASCII (ANSI) using codepage 1252.
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==Tools==
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===Open Source===
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* [https://www.pinguin.lu/index.php Forensic Registry EDitor (fred)] - "Forensic Registry EDitor (fred) is a cross-platform M$ registry hive editor" by [[Daniel Gillen]]
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* [http://projects.sentinelchicken.org/data/doc/reglookup/regfi/ libregfi] - The regfi library is a read-only NT registry library which serves as the main engine behind the reglookup tool
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* [http://projects.sentinelchicken.org/reglookup/ reglookup] — "small command line utility for reading and querying Windows NT-based registries."
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* [http://sourceforge.net/projects/regviewer/ regviewer] — a tool for looking at the registry.
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* [[Regripper|RegRipper]] — "the fastest, easiest, and best tool for registry analysis in forensics examinations."
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* [http://search.cpan.org/~jmacfarla/Parse-Win32Registry-0.51/lib/Parse/Win32Registry.pm Parse::Win32Registry] Perl module.
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* [http://www.williballenthin.com/registry/index.html python-registry] Python module.
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* [http://code.google.com/p/registrydecoder/ Registry Decoder] offline analysis component, by [[Andrew Case]]
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* [http://code.google.com/p/registrydecoder/ RegDecoderLive] live hive acquisition component, by [[Andrew Case]]
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* [[libregf]] - Library and tools to access the Windows NT Registry File (REGF) format
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* [[Registryasxml]] - Tool to import/export registry sections as XML
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===Freeware===
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* [http://www.tzworks.net/prototype_page.php?proto_id=3 Yet Another Registry Utility (yaru)] Free tool that can be run on Windows, Linux or Mac OS-X. If run in admin mode, allows viewing of registry hives on live system.
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* [http://www.tzworks.net/prototype_page.php?proto_id=14 Windows ShellBag Parser] Free tool that can be run on Windows, Linux or Mac OS-X.
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* [http://tzworks.net/prototype_page.php?proto_id=19 ''cafae''] - Computer Account Forensic Artifact Extractor.  Free tool that can be run on Windows, Linux or Mac OS-X to parse ntuser.dat hives.
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===Commercial===
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== File Formats ==
* [http://www.abexo.com/free-registry-cleaner.htm Abexo Free Regisry Cleaner]
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* [http://www.auslogics.com/registry-defrag Auslogics Registry Defrag]
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* [http://lastbit.com/arv/ Alien Registry Viewer]
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* [http://www.larshederer.homepage.t-online.de/erunt/index.htm NT Registry Optimizer]
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* [http://www.registry-clean.net/free-registry-defrag.htm iExpert Software-Free Registry Defrag]
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* [http://arsenalrecon.com/apps Registry Recon]
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* [http://paullee.ru/regundel Registry Undelete (russian)]
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* [http://mitec.cz/wrr.html Windows Registry Recovery]
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* [http://registrytool.com/ Registry Tool]
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==Bibliography==
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Data for SuperFetch is gathered by the <tt>%SystemRoot%\System32\Sysmain.dll</tt>, part of the Service Host process, <tt>%SystemRoot%\System32\Svchost.exe</tt>, and stored in a series of files in the <tt>%SystemRoot%\Prefetch</tt> directory [http://www.microsoft.com/technet/technetmag/issues/2007/03/VistaKernel/]. These files appear to start with the prefix <tt>Ag</tt> and have a <tt>.db</tt> extension. Note that there are likely more SuperFetch database files named differently, presumably all using the .db extension.
* [http://www.dfrws.org/2009/proceedings/p69-zhu.pdf Using ShellBag Information to Reconstruct User Activities], by Yuandong Zhu*, Pavel Gladyshev, Joshua James, DFRWS 2009
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* [http://www.dfrws.org/2008/proceedings/p33-morgan.pdf Recovering Deleted Data From the Windows Registry] and [http://www.dfrws.org/2008/proceedings/p33-morgan_pres.pdf slides], by [[Timothy Morgan]], DFRWS 2008
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* [http://dfrws.org/2008/proceedings/p26-dolan-gavitt.pdf Forensic Analysis of the Windows Registry in Memory] and [http://dfrws.org/2008/proceedings/p26-dolan-gavitt_pres.pdf slides], by Brendan Dolan-Gavitt, DFRWS 2008
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* [http://eptuners.com/forensics/A%20Windows%20Registry%20Quick%20Reference.pdf A Windows Registry Quick-Reference], by Derrick Farmer, Burlington, VT.
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* [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CW4-4GX1J3B-1&_user=3326500&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000060280&_version=1&_urlVersion=0&_userid=3326500&md5=ab887593e7be6d5257696707886978f1 The Windows Registry as a forensic resource], Digital Investigation, Volume 2, Issue 3, September 2005, Pages 201--205.
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The format of the SuperFetch database files is not fully known, there is available unofficial partial specification [http://blog.rewolf.pl/blog/?p=214] and open source (GPL) dumper for .db files [http://code.google.com/p/rewolf-superfetch-dumper/]. For more information see [[Windows SuperFetch Format|SuperFetch Format]].
  
* [http://www.forensicfocus.com/downloads/forensic-analysis-windows-registry.pdf Forensic Analysis of the Windows Registry], by Lih Wern Wong , School of Computer and Information Science, Edith Cowan University
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The SuperFetch feature is seeded with some basic usage patterns when the operating system is installed [http://channel9.msdn.com/showpost.aspx?postid=242429].
  
* [http://www.sentinelchicken.com/research/registry_format/ The Windows NT Registry File Format], by [[Timothy Morgan]]
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The SuperFetch service is managed by the File Information FS MiniFilter service. It appears that most of the SuperFetch database files are updated (written) when the service is shut down. AgAppLaunch.db is also written when the service starts.
  
==See Also==
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== See Also ==
* [http://windowsir.blogspot.com/search/label/Registry Windows Incident Response Articles on Registry]
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* [[Prefetch]]
* [http://www.answers.com/topic/win-registry Windows Registry Information]
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* [[ReadyBoost]]
* [http://en.wikipedia.org/wiki/Windows_Registry Wikipedia Article on Windows Registry]
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* [[ReadyBoot]]
[[Category:Bibliographies]]
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* [[Windows SuperFetch Format|SuperFetch Format]]
* [http://moyix.blogspot.com/search/label/registry Push the Red Button] — Articles on Registry
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* [[Windows]]
* [http://tech.groups.yahoo.com/group/win4n6/ Windows Forensics Mailing List]
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* [http://samba.org/~jelmer/kregedit/ kregedit] - a KDE utility for viewing and editing registry files.
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* [http://www.bindview.com/Services/RAZOR/Utilities/Unix_Linux/ntreg_readme.cfm ntreg] a file system driver for linux, which understands the NT registry file format.
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* [http://www.beginningtoseethelight.org/ntsecurity/ Security Accounts Manager]
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* http://www.opensourceforensics.org/tools/unix.html - Open Source Forensic Tools on Brian Carrier's website.
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== External Links ==
 +
* [http://technet.microsoft.com/en-us/magazine/2007.03.vistakernel.aspx Inside the Windows Vista Kernel: Part 2], by [[Mark Russinovich]], March 2007
 +
* [http://download.microsoft.com/download/7/E/7/7E7662CF-CBEA-470B-A97E-CE7CE0D98DC2/Win7Perf.docx Performance Testing Guide for Windows], by [[Microsoft]], August 18, 2009 
 +
* [http://en.wikipedia.org/wiki/Windows_Vista_I/O_technologies#SuperFetch Wikipedia: Windows Vista I/O technologies - SuperFetch]
 +
* [http://channel9.msdn.com/showpost.aspx?postid=242429 Channel 9 Interview with Michael Fortin of Microsoft on SuperFetch]
 +
* [http://www.informationweek.com/news/showArticle.jhtml?articleID=196902178 Microsoft Predicts The Future With Vista's SuperFetch] from Information Week
 +
* [http://jessekornblum.com/presentations/dodcc08-2.pdf DC3 Presentation: My You Look SuperFetching], by Jesse Kornblum
  
=== Windows 32-bit on Windows 64-bit (WoW64) ===
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== Tools ==
* [http://msdn.microsoft.com/en-us/library/aa384253(v=vs.85).aspx Registry Keys Affected by WOW64], by [[Microsoft]]
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=== Open Source ===
* [http://msdn.microsoft.com/en-us/library/aa384232(VS.85).aspx Registry Redirector], by [[Microsoft]]
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* [https://code.google.com/p/rewolf-superfetch-dumper/ rewolf-superfetch-dumper]
  
[[Category:Windows Analysis]]
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[[Category:Windows]]

Revision as of 06:10, 28 June 2014

Information icon.png

Please help to improve this article by expanding it.
Further information might be found on the discussion page.

SuperFetch is a performance enhancement introduced in Microsoft Windows Vista to reduce the time necessary to launch applications. SuperFetch works with the memory manager service in Windows to analyze memory usage patterns over time to determine the optimal memory content for a given user for a date or time of day. This differs from the Prefetch technique used in Microsoft Windows XP, which preloads data into memory without analyzing usage patterns.

From [1]: SuperFetch prioritizes the following kinds of pages to remain in memory:

  • Pages of applications that are used most frequently overall.
  • Pages of applications that are commonly used when resuming:
    • After extensive hibernation (for example, first thing in the morning).
    • After shorter periods of sleep or hibernation (for example, after lunch).

If SuperFetch detects that the system drive is a fast SSD (as measured by Windows Experience Index Disk score), then SuperFetch turns off ReadyBoot, ReadyBoost, and the SuperFetch service itself.

Components

Robust performance

Robust performance (or robustness) is a component of SuperFetch to watch for specific file I/O access that might harm system performance by populating the standby lists with unneeded data.

Scenarios

SuperFetch distinguishes between different scenarios to accurately measure performance.

Cold scenario

In a cold scenario, the test applications are not already in memory when the test begins. Cold scenarios measure performance either after a state transition, such as boot or resume from hibernation, or after another application claims most of the available memory, such as after launching and quitting a game.

Warm scenario

In a warm scenario, some or all the scenario contents are in memory before measurement. This usually means that the test has run at least once during this logon session.

Configuration

Because SuperFetch appears to leave a system with no available memory, some users turn it off to create the appearance of having more free memory. The feature can be configured by changing the Registry value [2]:

Key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters
Value: EnableSuperfetch

A value of zero disables SuperFetch, one enables it for booting only, two for applications, and three for both applications and boot. This setting can also be changed using the Services console, services.msc [3].

File Formats

Data for SuperFetch is gathered by the %SystemRoot%\System32\Sysmain.dll, part of the Service Host process, %SystemRoot%\System32\Svchost.exe, and stored in a series of files in the %SystemRoot%\Prefetch directory [4]. These files appear to start with the prefix Ag and have a .db extension. Note that there are likely more SuperFetch database files named differently, presumably all using the .db extension.

The format of the SuperFetch database files is not fully known, there is available unofficial partial specification [5] and open source (GPL) dumper for .db files [6]. For more information see SuperFetch Format.

The SuperFetch feature is seeded with some basic usage patterns when the operating system is installed [7].

The SuperFetch service is managed by the File Information FS MiniFilter service. It appears that most of the SuperFetch database files are updated (written) when the service is shut down. AgAppLaunch.db is also written when the service starts.

See Also

External Links

Tools

Open Source