The Impact of SuperFetch on Vista Memory Usage and Performance
As we've already explained, the premise behind SuperFetch is simple - it's an intelligent software mechanism that monitors frequently used pages and does its best to keep them in memory. In other words if you run Photoshop a lot, SuperFetch will take notice and try to keep Photoshop.exe and its associated libraries in main memory so long as you don't need that memory for anything else. The real world impact of SuperFetch is tremendous: the more memory you have, the more your frequently used applications will load very quickly.
SuperFetch works like this: Vista will load anything it needs to load in memory first, and any applications you manually run will also be loaded into memory. Any memory left over is fair game to be used by SuperFetch as a cache of frequently used pages. Vista keeps track of what memory pages are frequently requested and what files they are tied to, and based on that data SuperFetch will populate as much free memory as it can with pages it believes you will need in the future. This data contains both frequency and temporal history, so not only how often but when you run these applications will influence what SuperFetch does at any given time.
SuperFetch has a number of counters and data structures that have to be loaded into main memory to make this whole process work. The end result is that SuperFetch is part of what makes Vista's memory requirements greater than XP's, but if you've got the memory to spare the payoff is huge.
While it's very difficult to benchmark the impact of SuperFetch well, in our usage of Vista if you have enough memory it is a tremendous ally. Honestly SuperFetch is the biggest reason, in our opinion, to move to the x64 version of Vista so you can use even more memory. Although we found that 2GB of memory is still quite passable under Vista, the new sweet spot if you happen to multitask a lot is 4GB - in no small part due to how well SuperFetch utilizes the additional memory. Do keep in mind that you'll need to make sure your motherboard has proper BIOS support for 4GB and also make sure Vista x64 has driver support for all of your peripherals before committing to the move.
In an ideal world, you'd have more than enough memory for SuperFetch to go out and pull all of your regularly used pages into main memory so that all applications would load without waiting on your hard drive. In reality however, the vast majority of computers have less than 2GB of memory, and when multitasking there's simply not that much room in memory to keep other large applications cached. SuperFetch wouldn't be a very useful technology if it kept cached pages active in memory even when you needed that memory for other applications, and thus if you run out of memory SuperFetch will begin swapping its cached pages out to disk from main memory.
SuperFetch is intelligent however; as soon as you are done with the application that evicted cached data from main memory, SuperFetch will bring those frequently used pages back into main memory.
Repopulating the SuperFetch buffer is a time and disk intensive process; think about how long it takes to copy 1GB of data off of your disk and you'll have a good idea of how long it will take for SuperFetch to recover evicted data. With a good amount of historical data, SuperFetch will often take a couple of minutes after Vista starts up to begin pulling data into memory from the disk, which means you'll be hearing quite a bit of disk activity as it does this. This also means that a faster disk will help SuperFetch behave more seamlessly, although you're still better off spending money on more memory to keep SuperFetch from having to page back to disk.
Quick Recommendations
How much RAM do you really need for Windows Vista? We recommend a bare minimum of 1GB of memory for all Vista users, 2GB if you're a power user but don't have a lot running at the same time, and 4GB if you hate the sound of swapping to disk. While SuperFetch definitely makes applications load faster when it works, it's still difficult to say for sure how effective it is without more testing time. Routines can sometimes change, so it will be interesting to see how fast SuperFetch can adapt to new usage patterns. We're also not sure how frequent gaming (which can easily use several GB of data in a session) will affect SuperFetch, so that's something that we will have to assess more as time passes.
As we've already explained, the premise behind SuperFetch is simple - it's an intelligent software mechanism that monitors frequently used pages and does its best to keep them in memory. In other words if you run Photoshop a lot, SuperFetch will take notice and try to keep Photoshop.exe and its associated libraries in main memory so long as you don't need that memory for anything else. The real world impact of SuperFetch is tremendous: the more memory you have, the more your frequently used applications will load very quickly.
SuperFetch works like this: Vista will load anything it needs to load in memory first, and any applications you manually run will also be loaded into memory. Any memory left over is fair game to be used by SuperFetch as a cache of frequently used pages. Vista keeps track of what memory pages are frequently requested and what files they are tied to, and based on that data SuperFetch will populate as much free memory as it can with pages it believes you will need in the future. This data contains both frequency and temporal history, so not only how often but when you run these applications will influence what SuperFetch does at any given time.
SuperFetch has a number of counters and data structures that have to be loaded into main memory to make this whole process work. The end result is that SuperFetch is part of what makes Vista's memory requirements greater than XP's, but if you've got the memory to spare the payoff is huge.
While it's very difficult to benchmark the impact of SuperFetch well, in our usage of Vista if you have enough memory it is a tremendous ally. Honestly SuperFetch is the biggest reason, in our opinion, to move to the x64 version of Vista so you can use even more memory. Although we found that 2GB of memory is still quite passable under Vista, the new sweet spot if you happen to multitask a lot is 4GB - in no small part due to how well SuperFetch utilizes the additional memory. Do keep in mind that you'll need to make sure your motherboard has proper BIOS support for 4GB and also make sure Vista x64 has driver support for all of your peripherals before committing to the move.
In an ideal world, you'd have more than enough memory for SuperFetch to go out and pull all of your regularly used pages into main memory so that all applications would load without waiting on your hard drive. In reality however, the vast majority of computers have less than 2GB of memory, and when multitasking there's simply not that much room in memory to keep other large applications cached. SuperFetch wouldn't be a very useful technology if it kept cached pages active in memory even when you needed that memory for other applications, and thus if you run out of memory SuperFetch will begin swapping its cached pages out to disk from main memory.
SuperFetch is intelligent however; as soon as you are done with the application that evicted cached data from main memory, SuperFetch will bring those frequently used pages back into main memory.
Repopulating the SuperFetch buffer is a time and disk intensive process; think about how long it takes to copy 1GB of data off of your disk and you'll have a good idea of how long it will take for SuperFetch to recover evicted data. With a good amount of historical data, SuperFetch will often take a couple of minutes after Vista starts up to begin pulling data into memory from the disk, which means you'll be hearing quite a bit of disk activity as it does this. This also means that a faster disk will help SuperFetch behave more seamlessly, although you're still better off spending money on more memory to keep SuperFetch from having to page back to disk.
Quick Recommendations
How much RAM do you really need for Windows Vista? We recommend a bare minimum of 1GB of memory for all Vista users, 2GB if you're a power user but don't have a lot running at the same time, and 4GB if you hate the sound of swapping to disk. While SuperFetch definitely makes applications load faster when it works, it's still difficult to say for sure how effective it is without more testing time. Routines can sometimes change, so it will be interesting to see how fast SuperFetch can adapt to new usage patterns. We're also not sure how frequent gaming (which can easily use several GB of data in a session) will affect SuperFetch, so that's something that we will have to assess more as time passes.
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Zebo - Thursday, February 1, 2007 - link
I'm still on 2k pro which I think is faster and more power-user friendly than XP. Is this true in general? I've never noticed a security issue in the first place so these security features and especially those silly "do you really want to run this program" dialog boxes drove me crazy on XP when I tried it. Does vista have a lot of those? Stupid OS I wouldn't have clicked it if I didn't want to run/install/throw it away etc.Aikouka - Thursday, February 1, 2007 - link
Zebo, it sounds like if you run Vista and don't disable UAC (User Account Control), you will drive yourself crazy. UAC almost literally warns you about every executable opening (I believe certain ones are allowed automatically, like Windows Explorer. I can't remember since I turned it off :P).Other than that, I don't see anything really different from XP in terms of user warnings and such. There's still the balloons from the system tray and such.
One interesting change that I haven't seen anyone mention is how Windows Update is now an application instead of a website. It seems a bit nicer having it that way as the website with the ActiveX controls always felt so slow to figure out what needed to upgraded. This new WU also includes Ultimate Extras and direct program links to adjust your WU settings (which is handier I think).
Zebo - Thursday, February 1, 2007 - link
I guess thats a good idea if you use windows update. I don't update just for updates sake subscribing to the "if it aint broke don't fix it" axiom...probably why I still use w2k:)
Zebo - Thursday, February 1, 2007 - link
Oh that's maddening. I literally offered $100 to anyone in a forum thread who could turn those yellow balloons off completely when i tried XP. No one could do it. You can't turn certain ones off despite tens of registry tweaks we tired.
Zorba - Friday, February 2, 2007 - link
The balloons are easy to get rid of. http://www.microsoft.com/windowsxp/downloads/power...">TweakUI - FTWNot sure if it will be in Vista or not, but works great in XP, never seen a balloon except right after I install XP. PM me and I'll let you know where you can send me my check ;).
Zebo - Friday, February 2, 2007 - link
BS doesn't work. Been there done that! Show me a SS with you holding mouse over Start button and it doesn't say "click here to begin" I'll gladly pay you $100 for the fix. You can't do it. BTW this drives me fusken crazy! I've been using MS start buttons for eight years like I don't WTF Start means and designates ..ArrrZorba - Friday, February 2, 2007 - link
Ah I thought you were talking about the system tray balloons like that one that always pops up for no reason that always says "now connected to wireless network." That one drives me crazy when I use someone else's lappy.I never even notice the ones over the start button, I guess I never hold my mouse over it long enough. I could see how you would find them annoying though.
Zorba - Friday, February 2, 2007 - link
BTW: I just checked and Win 98 has those boxes over if hold your mouse over the start button, etc too. So it isn't just an XP thing. (Yes I still have 98 on a box at home)stash - Thursday, February 1, 2007 - link
Not even close. UAC will prompt you for things that require elevated rights, which besides installing apps or making changes to the system, should be very infrequent.
Which is why I want to know specifically which common 3rd-party apps the author is referring to on the first page.
Aikouka - Friday, February 2, 2007 - link
Well, I guess my statement may've been a bit zealous, but you can't forget that literally every application that I ran while UAC on was an install or a system executable to install software that I needed or change settings. The changing the settings may've seemed the worst, as trying to open the system menu from another menu required your authorization. It was a bit crazy sometimes...