Understanding Superfetch in Windows 7

[ToneKnee]

Word 2007 takes ~2 seconds to load on my Raid 0 setup without superfetch. As I said long time ago, if you even have good Raid 0 (with standard HDDs) setup Superfetch is useless.

Superfetch is still beneficial, any ways, this topic has served it's purpose, no more Superfetch bashing.

[jamesVault]

SuperFetch also includes specific scenario support for hibernation, standby, Fast User Switching (FUS), and application launch. When the system hibernates, for example, SuperFetch stores data and code in the hibernation file that it expects (based on previous hibernations) will be accessed during the subsequent resume. In contrast, when you resume Windows XP, previously cached data must be reread from the disk when it is referenced.

http://technet.microsoft.com/en-us/magazin...istakernel.aspx

[HawkMan]

Word 2007 takes ~2 seconds to load on my Raid 0 setup without superfetch. As I said long time ago, if you even have good Raid 0 (with standard HDDs) setup Superfetch is useless.

Maybe you should measure on a more demanding app than Word... like Softimage, Maya, 3DSMAX, Photoshop, Lightroom, Games....

[PNutts]

This thread is mostly opionion (and much of it misinformed) so I skipped reading all of it. Sorry if this was already posted:

Here's a link to the Engineering Windows 7 blog that describes Windows 7 behavior on SSD disks. What's interesting that Windows 7 changes it's behavior depending on the speed of your drive(s). A slow SSD disk will be treated the same as a slow HDD and a fast SSD will be treated the same as a fast hard drive. If a drive is fast enough all the "helpers" (superfetch, etc.) are turned off. It's an assessment of your hard drive's performance.

Support and Q&A for Solid-State Drives

http://blogs.msdn.com/e7/archive/2009/05/0...drives-and.aspx

[soulburner]

I would consider this normal behaviour, because the .vdi file needs to be saved by VirtualBox. This disk activity is caused by VirtualBox.

No, because if the file would be saved by VirtualBox you would see virtualbox.exe - not svchost.exe with Background IO priority - and it would be written, not read ;)

[morphen]

Why don't we just delay this discussion until some idiot puts out an tweak-guide where he/her tells us to disable superfetch "because it eats up all your ram" ?

And I bet he/she is going to suggest we should set "number of processors" to 2/4/6/8 whatever we have, so windows ACTUALLY uses them, so then we will have a bonus discussion.

bah :p I'm already getting agitated.

[jamesVault]

if the file would be saved by VirtualBox you would see virtualbox.exe - not svchost.exe

VirtualBox's low level components are services hosted in svchost.exe

Edited June 10, 2009 by jamesVault

[gshapiro]

Might be of interest:

http://bink.nu/news/atm-the-cache-machine.aspx

[Defcon]

I haven't had any time to run tests or even check stuff out using process explorer, but I use Visual Studio all day and that is a pig of a program, it can slow down the fastest of pc's. My workstation is a dual Xeon 2.4Ghz with 4Gb (out of which I use 3 since I'm still on Win32).

With Win7 7100, I don't see any subjective difference with superfetch on or off. I know VS does a ton of disk Io and the pagefile is frequently being hit, so IMO even after weeks of superfetch being on, its not good enough at predicting disk access and avoiding a cache miss.

[flip_guest]

Sorry to revive this thread but i caught it on google

Superfetch should be disabled with SSD's since it can cause additional stress on the drives.

SSD's are only worn when using a write I/O. Reading causes no wear on a SSD. Superfetch uses read I/O to cache data into your RAM. It may cause some write but nothing significant.

On another note, Superfetch on Vista really is terrible especially for notebooks. It will eat up your battery because of over using your HD to cache stuff in your RAM. If you have 6gb of RAM, your HD will be thrash about 4-5mins straight trying to fill up your RAM. Yes it will fill your RAM with stuff your going to use but ALOT more of crap your not going to use. Basically not worth that HD/power usage seeing as disabling it makes no difference in performance, HD's these days are fast enough to load a ton of stuff. Also It doesnt just prefetch stuff at startup, it will repopulate every time your memory is free.

If you disable it, you will notice that login time will be faster and more responsive, reverting to an XP style memory management.

I havent tried Windows 7 but i hope they made some adjustments. I also believe unused RAM is wasted ram, but not at the cost of my HD's resources. To be honest i think its just as bad as "ReadyBoost"

Cheers.

[ToneKnee]

Sorry to revive this thread but i caught it on google

SSD's are only worn when using a write I/O. Reading causes no wear on a SSD. Superfetch uses read I/O to cache data into your RAM. It may cause some write but nothing significant.

On another note, Superfetch on Vista really is terrible especially for notebooks. It will eat up your battery because of over using your HD to cache stuff in your RAM. If you have 6gb of RAM, your HD will be thrash about 4-5mins straight trying to fill up your RAM. Yes it will fill your RAM with stuff your going to use but ALOT more of crap your not going to use. Basically not worth that HD/power usage seeing as disabling it makes no difference in performance, HD's these days are fast enough to load a ton of stuff. Also It doesnt just prefetch stuff at startup, it will repopulate every time your memory is free.

If you disable it, you will notice that login time will be faster and more responsive, reverting to an XP style memory management.

I havent tried Windows 7 but i hope they made some adjustments. I also believe unused RAM is wasted ram, but not at the cost of my HD's resources. To be honest i think its just as bad as "ReadyBoost"

Cheers.

Superfetch is disabled when you use a SSD on Windows 7. And Microsoft disabled it for a good reason, not to mention that Superfetch isn't really needed with an SSD.

[ViperAFK]

Sorry to revive this thread but i caught it on google

SSD's are only worn when using a write I/O. Reading causes no wear on a SSD. Superfetch uses read I/O to cache data into your RAM. It may cause some write but nothing significant.

On another note, Superfetch on Vista really is terrible especially for notebooks. It will eat up your battery because of over using your HD to cache stuff in your RAM. If you have 6gb of RAM, your HD will be thrash about 4-5mins straight trying to fill up your RAM. Yes it will fill your RAM with stuff your going to use but ALOT more of crap your not going to use. Basically not worth that HD/power usage seeing as disabling it makes no difference in performance, HD's these days are fast enough to load a ton of stuff. Also It doesnt just prefetch stuff at startup, it will repopulate every time your memory is free.

If you disable it, you will notice that login time will be faster and more responsive, reverting to an XP style memory management.

I havent tried Windows 7 but i hope they made some adjustments. I also believe unused RAM is wasted ram, but not at the cost of my HD's resources. To be honest i think its just as bad as "ReadyBoost"

Cheers.

Login on my pc's with superfetch is just as fast as it is with it off, that's nonsense. And I use sleep mode on my laptop so I open it and superfetch already ahs everything loaded, imagine that!

[ToneKnee]

Login on my pc's with superfetch is just as fast as it is with it off, that's nonsense. And I use sleep mode on my laptop so I open it and superfetch already ahs everything loaded, imagine that!

Are you using Windows Vista or Windows 7? Windows Vista caused boot slowdowns because it was trying to cache everything to the memory while at the same time trying to load up other start up items. Windows 7 doesn't do this and caching only starts when your computer is idle or shortly after the system is fully started up and it only caches only what you need and not everything like in Vista.

[franzon]

Windows Vista caused boot slowdowns because it was trying to cache everything to the memory while at the same time trying to load up other start up items.

that's completely false!!!!

[ViperAFK]

Are you using Windows Vista or Windows 7? Windows Vista caused boot slowdowns because it was trying to cache everything to the memory while at the same time trying to load up other start up items. Windows 7 doesn't do this and caching only starts when your computer is idle or shortly after the system is fully started up and it only caches only what you need and not everything like in Vista.

My pc boots in 35 seconds to a usable desktop... with both vista and 7, xp actually booted a bit slower.

And this pc is nothing special, no ub3r fast drives or SSD's.

[Orien]

W7 delays the start of Superfetch a little while after boot and isn't as aggressive.

[Dumeowin]

Well on Win7x64, Superfetch crashes too much for me for some reason after a few weeks period of no problem, so finally disabled and won't enable it again until SP1. lol