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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haplo602 - Monday, February 5, 2007 - link
Yes I am biased. I am fed up with MS. All the delay was for what purpose ?Yes please, point me to the documentation, I'd be glad to learn something.
vailr - Thursday, February 1, 2007 - link
A quick look on Newegg shows the least expensive DX 10 cards (all NVIDIA 8800 based) are priced around $400. When can we expect to see DX 10 cards costing: <$200?Brazos - Friday, February 2, 2007 - link
I believe that Nvidia is releasing a broader range of directx 10 gpu's in March. They're supposed to be for the low - mid range video cards.PrinceGaz - Thursday, February 1, 2007 - link
Vista Enterprise/VLK also includes BitLocker, it is not a feature unique to Ultimate Edition, but like you say it requires a TPM to be used and if I had a TPM on my mobo, I certainly wouldn't have the hateful chip enabled.
Before you say that Vista Enterprise is not a copy that any of us are likely to personally choose, because unlike XP it still requires activation, bear in mind that Enterprise edition activation is rather different from other versions and likely to be the first that is cracked indefinitely. Given that you also recommended Vista Business as the preferred version of Vista for experienced users unwilling to pay the extra for Ultimate, that makes Enterprise even more viable as it includes a superset of Vista Business features and the only things it is missing from Ultimate are a few entertainment oriented apps that no one will miss. That's not to say I condone unlicensed use of Vista Enterprise, I'd never say anything like that here, but I think the use of it may be a lot more prelavent than the article suggests.
stash - Friday, February 2, 2007 - link
BitLocker does NOT require a TPM chip. It can also use a usb flash drive to store the key material.
Ryan Smith - Saturday, February 3, 2007 - link
BitLocker requires a TPM chip. This confused us at first too when we were working on the article, but the documentation in Vista for BitLocker clearly states a TPM chip is required. If it's a 1.2 chip or higher the key is stored on the chip, otherwise it's stored on the flash drive.If it was possible to use BitLocker without a TPM chip, we would have more than likely thrown in some BitLocker benchmarks.
mlambert890 - Saturday, February 3, 2007 - link
You're wrong Ryan. BitLocker does NOT require TPM chip. You can store the decrypt AND recovery keys on a USB FOB. Just go here and read scenario 3:http://technet2.microsoft.com/WindowsVista/en/libr...">http://technet2.microsoft.com/WindowsVi...57-b031-...
Ryan Smith - Saturday, February 3, 2007 - link
Interesting; we looked for something like this when we were doing the prep for this article and came up empty-handed. It's nice to see it's there, though I'm not sure for the reason on why MS would go out of their way to disable this option and not leave any instructions in the Vista help on how to enable it. Thanks for the link.stash - Saturday, February 3, 2007 - link
Couple of reasons:First, it is a hell of a lot more secure to use a TPM to store key material than a USB flash drive. A TPM is essentially a smartcard soldered directly to your motherboard. It is physically and logically tamper-resistant.
Secondly, BitLocker will only do repudiation checks of the system files with a TPM. When using a TPM. the hashes of certain system files are stored in the TPM. On boot, they are compared and if they have been changed, the user will be notified.
So, are you going to answer my question about which common 3rd party apps require admin rights to work properly? Cause right now, my impression of that comment is that it is pure FUD.
LoneWolf15 - Friday, February 2, 2007 - link
I was concerned about this too, but my new issue of MaximumPC shows how to use Vista's BitLocker without a TPM.Instead of the TPM holding the security key, you need a thumbdrive to do it instead. Doesn't require a high-capacity one, so any cheapie should do (though I'd choose one with a somewhat bulletproof casing to ensure you never break it and end up screwed).