New I/O Features

One set of features we have held off on discussing in-depth until now have been the I/O related features in Vista, including ReadyBoost, ReadyDrive, SuperFetch, and the new networking stack. We'll get to the new networking stack in a bit, but first the Ready features and SuperFetch merit a bit of discussion.

SuperFetch

Depending on the scenario, a great deal of computing time is spent waiting for data retrieval due to processors being significantly faster than the mass storage devices. To that extent modern computers have a hierarchy of several levels of data caches to store and manipulate data, ranging from registers and L1 cache down to hard drives and their own cache. This system of cache layers works very well in hiding the speed differences between various layers, but there are still large gaps between places such as the CPU and RAM, and RAM and hard drives. One possible improvement - and certainly the most effective solution that Microsoft has implemented in Vista - is to try to move up required data to a higher layer, in this case by keeping more data in RAM than just the bare minimum.

The result of this is the first I/O improving technology, SuperFetch, a new technology designed to cache as much data as RAM space allows. Previously, Windows XP had a more basic implementation of this idea called prefetch, which used trace logs of programs loading in order to help XP optimize the loading sequence. SuperFetch in turn takes things a step further by not only figuring out what data is required to launch an application, but it actually loads this data into memory as space allows so that if it's needed at a later point the data is already in RAM instead of still residing on the hard drive.

In practice, SuperFetch depends a great deal on how predictable a user is and how much extra RAM a computer has. Veteran computer users will be slightly dismayed at first to find that Vista is actively attempting to use the entirety of a computer's RAM (down to 0MB of free memory remaining), which is effectively the opposite of how XP attempted to conserve as much memory as possible. This looks worse than it actually is, as cached data can immediately be thrown away to make space for an application as required, but Microsoft has nonetheless attempted to clarify things since Beta 2 where the Task Manager would only show total memory usage. Now the Task Manager makes it clear how much RAM is being used for program execution and how much is being used for cache, but this will still inevitably spark a few debates on if full RAM usage is really a good thing. Given that RAM tends to be a low power device operating at near full power all the time (especially on desktop machines), we feel RAM is the ideal underutilized component to try to fully exploit, as it doesn't incur the extra power costs of running at full load like a CPU/GPU do.


However as we mentioned previously, the total benefit is dependent in predictability and excess RAM. As SuperFetch is designed to predict what applications a user may load next and then pre-load them into cache (i.e., a user loads Outlook at 10am every day), it works better for users with routines than those without. Similarly, as Vista attempts to use all RAM for the cache, it can always benefit from more RAM to keep more things cached (a behavior similar to MacOS X).

Index How Much RAM?
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  • nishzone - Saturday, May 24, 2008 - link

    Hi,

    I'm glad tnat your memory usage is similar to mine and therefore I might finally understand this. You have 2 gig of Ram...I understand that superfetch is the reason free ram is 0 (cache increases as free memory decreases). But why is the memory usage 45%? so around 1 gig?

    I also have 50% usage on startup. Is vista using 1 gig memory? There is something I don't understand here because you recommended 1 gig for general users.

    Regards,
    Nishzone
  • Dataland - Wednesday, November 28, 2007 - link

    I think Microsoft needs a performance reset. As I've said in some previous posts, I think software in general, and Microsoft software in particular, is getting slower at faster rate than hardware is getting faster. And this problem acutely affects Vista. I think Microsoft needs... (Pingback)

    Performance Reset
    http://dataland.wordpress.com/2007/11/28/performan...">http://dataland.wordpress.com/2007/11/28/performan...
  • Kondado - Saturday, February 10, 2007 - link

    I've done my own tests. I sent the same amount of data (51 files, 2,5 GB) once from XP to Samba, then from Vista to Samba (OpenBSD). Then I did the same from XP to XP, and from Vista to XP. XP was always a LOT faster.

    I would really know if it's the drivers or the stack...
  • jonp - Monday, February 5, 2007 - link

    It seems like the budget system area was a little overlooked in this review of Vista. So I have some questions:

    "Memory in Vista..." - It appears that acceptable multitasking performance is found somewhere in the 3GB to 4GB memory size area. Many budget systems have only two memory slots and many new ones support dual memory access. This will force budget systems to 4GB which is fairly pricey now and probably will be for some time.

    "CPU Performance..." - Your love for anything Core2 Duo shines here. But what about the dual core Pentium Ds? Like the D915 2.8GHz processor. Yes it is Netburst, but also easier on the budget than a Core 2 Duo processor. We need something more specific here in terms of benchmarks/guidelines.

    Video adapters - I didn't see anything that talked about integrated video adapters vs. VGA/PCIe video adapters. Are any of the integrated graphic engines, like Intel 950GMA provide acceptable performance for VISTA? How about older video cards? Minimum graphics memory? Graphics engine speed? Again we need more specific guidance here.

    Hard drive - You addressed hard drive performance, in a way, in the "Vista Search for Fast Drives Only" section. But again no specific device selection guidelines like: RPM, cache size, average access, size, data transfer rate, ...

    Virtualization - It appears that MS forbids the use of virtualization products with Vista Home Basic and Home Premium editions forcing budget users to more costly editions of Vista.

    Upgrade or "clean" install? - Not strictly a budget system issue; the web if full of warnings about NOT trying to upgrade to Vista --- that it should only be a "clean" install situation. That upgrading is fraught with too many pitfalls that it isn't even worth trying. And not all editions of Vista are allowed to do in-place upgrades of the XP editions; oh, and you can't do an in-place upgrade of anything prior to XP. See http://tinyurl.com/36ljxv">http://tinyurl.com/36ljxv for some upgrade details.
  • JarredWalton - Monday, February 5, 2007 - link

    quote:

    Even with a lengthy preview article, there is still a lot of ground to cover when taking a close look at the final release version of Windows Vista. We have attempted to create a comprehensive look at the new operating system, but even then there are still plenty of items that will have to wait for another day before we can truly evaluate them.


    Basically, a lot of that falls into areas we are going to look at in future articles. Given that we don't really recommend most people upgrade to Vista yet, the lower-end your system is the less we would consider Vista. Pretty much all of the DX9 NVIDIA and AMD cards do fine with the Vista Aero Glass UI, but IGP solutions are slower. Individual tolerance for the UI will vary; I'm sure plenty will be okay with GMA950 and Glass, while others won't want anything less than a $100 discrete GPU. Oh, and GPU drivers for Vista are still flaky, IMO. :)

    HDD, anything 7200 RPM should be fine. CPU, really with a decent GPU the requirements aren't all that much higher than XP. RAM is more important - don't even think about Vista with less than 1GB - but HDD and CPU most people with anything made in the past two years will be fine. Just my opinion there - individual usage and preferences will again play a role.

    I wouldn't say 3-4GB of RAM is even remotely necessary for most people. A few will like it, but 2GB is still sufficient for about 99% of people.

    Virtualization and Upgrades... I'll have to defer to others there. Again, I recommend discretion, so I would tend towards doing a full backup (Ghost or similar) of any system before doing a Vista upgrade. I believe Gary is about to revert his system for the time being, as Vista has just had a few too many glitches. The number of people that worry about virtualization - really intending to use it, not just for test purposes - is again very small. I think mostly we're seeing the vocal minority complaining. Still, I find it odd that MS even worries about whether or not people run the OS via virtualization - unless the glitches are aggravated by such an environment, which is entirely possible.
  • jonp - Tuesday, February 6, 2007 - link

    Thanks Jarred...you insights are always very helpful and I am glad that these topics will get more focus in the future. Jon
  • jonp - Monday, February 5, 2007 - link

    Both of the charts in the Compound TCP section for Windows Vista say "Compact" and not "Compound".
  • duploxxx - Sunday, February 4, 2007 - link

    Its probably me that's missing a page or so but could you guys explain what system you used for these tests?
  • funk3y - Saturday, February 3, 2007 - link

    Hello

    I also spent some time testing the network part of windows vista, and I discovered some quite interesting things:

    Windows Vista is reducing the network I/O when an application using the audio interface is launched, I discovered this when copying large files over my network.

    When I copy large file through the network the average speed is 40 mb/sec and the taskmanager whow 30-50% of network use, as soon as I start an application playing sound (WMP, Skype, Warcraft III, ....) the rate drop to 8 mb/sec and the network use in the taskmanager never go beyond 12.5%

    I achieved those test on different hardware, with differents drivers and the results are always the same; it is just impossible to get further then 12.5% of network use while playing a sound.

    My guesses are that microsoft voluntary did this, in order to avoid sound crackling. Because of the new driver scheme, bad written drivers having to do many I/O could lead to sound degradation (I had this issue while using my raptors RAID on a NF4 board; making a lot of I/O on the disk just killed the sound quality).

    As you where streaming a film while benchmarking, you may have been in this situation. It could be nice if you could rerun some benchmark taking into account all what I have written.

    As I am already posting, here are some other consideration about DOS and vista:
    -It is just impossible to launch a DOS application in fullscreen mode! This functionnality lack can be really painfull in environnement where DOS application are still well used; I just don't understand microsoft's choice
    -I don't think that vista x64 is still able to launch 16 bit apps anymore (keep this in mind before upgrading to x64!)
  • ministerchief - Saturday, February 3, 2007 - link

    I have a "Corsair Flash Voyager 4Gb" usb stick and I can't use it to "BOOST" my system.

    So, how anandtech could use it ?

    Can someone tell me how to use this flash drive with the "READY BOOST" feature.


    THX

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