TweakHound - Tweaking Windows 7
The Page File, SuperFetch, and ReadyBoost
The Page File
1. The average user is best served by LEAVING THE PAGE FILE
ALONE. Windows 7 does an excellent job of managing the page
file settings for most people.
2. For 99.999% of the configurations on the planet you need
a page file. Windows 7 itself wants one and a number of
programs out there do too. If you think you can run your
machine optimally without a page file you do not understand
how Windows 7 (or any NT based OS works).
(Please don't email me to argue this, I won't respond. Find
a forum to argue about it.)
3. The recommendations below are not designed to give you
the highest scores on a synthetic benchmark but to give you
the best overall performance for your system (including
stability). The size of hard drives today are huge and
making the page file a little larger than it "needs" to be
hurts nothing and you're covered if you're ever doing
something that requires more.
"Page file size equal to RAM: Prior
to Windows 7 the default paging file size was determined
differently on different versions of Windows. But in general
terms, when the paging file size was configured as
“system-managed” its size would typically be calculated
as RAM x (some number greater than 1) or RAM + (some
In Windows 7 and Server 2008 R2 the default size is
equal to the amount of memory installed in the machine. Your
gut reaction to this is probably the same as mine was – to
get a successful complete memory dump the paging file needs
to be a little larger than RAM. How much larger probably
goes back to what version of Windows you are running and
other factors, but 300 MB is generally considered plenty of
padding for the purposes of getting a complete dump.
Not to worry. A default installation of Windows 7 or
Server 2008 R2 is configured to generate a kernel memory
dump and also with a system-managed paging file size. So a
paging file equal to RAM is plenty. If you decide
that you want to capture a complete memory dump, simply
change the dump option to “Complete memory dump” and
restart (be sure to leave the paging file size as
system-managed). After the restart the paging file
should be RAM + 300 MB. This applies to both client and
ASKPERF - Windows 7 / Windows Server 2008 R2: Upgrade Paths,
Registry Enhancements, Crash Dumps and Page File Sizing
One hard drive:
If you only have one hard drive or your other drives are
significantly slower than your OS drive. Leave it alone.
Two hard drives:
The second drive should be near as fast or faster than the
OS drive or there is no reason to do this.
Make 2 page files, one on the OS drive, one on the first
partition of the second drive. The page file on the OS drive
should be at least 300MB. The second page file should be
equal to the amount of RAM (physical memory) or
System managed size
***Author's note - Based on emails I've received I do not
seem to be making myself clear. If you have one hard drive
DO NOT MOVE OR MAKE A SECOND PAGE FILE. If you have 2 drives
and you make a second page file you should leave at least a
small page file on the OS partition. The second page file
should be on the FIRST PARTITION of the second drive.
To adjust page file settings:
Press the Windows
+ Pause Break
keys > in the left pane click on Advanced system
> click on the Advanced
tab > in the
section click the Settings...
click on the Advanced
tab . click on the
button. Highlight the drive you wish to work with.
Below are some examples from a system with 2GB of RAM.
2GB of RAM, 300MB pagefile on OS drive, System managed
pagefile on 2nd drive.
My recommendation: Unless you have a fast RAID setup or SSD
then don't mess with it.
"In Windows 7, SuperFetch is
enabled for disks that have a low Windows Experience Disk Score and
disabled for disks that have a high score. During
performance testing, you should use the default SuperFetch
setting because it represents actual end-user experience.
SuperFetch adds the prefetched pages to the system’s
standby page list, which has been reorganized and redesigned
to retain useful data in memory over longer periods of time.
Both Windows 7 and Windows Vista set priorities for pages on
the standby list so that historically important pages remain
in memory and less frequently used pages do not. For
example, the prefetched pages of a frequently used program
have a higher priority than those of a recently copied file
that might not be used again."
Performance Testing Guide for Windows
"If the system disk is an SSD, and the SSD performs
adequately on random reads and doesn’t have glaring
performance issues with random writes or flushes, then
Superfetch, boot prefetching, application launch
prefetching, ReadyBoost and ReadDrive will all be disabled."
Engineering Windows 7 - Support and Q&A for Solid-State
One problem with the above 2 statements . I have an SSD disk
(specifically the Intel X25-M Generation 2). My Windows
Experience score for Primary hard disk is 7.7 (out a
possible 7.9). Windows 7 did not disable the service nor
adjust the registry settings. It is visible via Task Manager
(SysMain) and actively using system resources. I'm
interested if anyone has had Windows 7 disable this as they
claim. I would also like to know what qualifies as a high
"Windows Experience Disk Score" according to Microsoft.
Superfetch Improvements For Windows 7
"During Windows7 development, we made a number of
improvements to how Superfetch manages memory. Many of these
changes were directly in response to customer comments. At a
high level, some of these improvements are as follows:
(1) Be quieter: Even though Superfetch always utilizes
low-priority I/O for its memory population in order to avoid
interfering with foreground activity, we found that many
users get annoyed at hearing the disk activity and seeing
the disk light blink. In Windows7, Superfetch is a lot more
respectful of user presence.
(2) Be more selective: In Windows7, Superfetch still
populates the OS cache with frequently-accessed data from
the disk and prioritizes RAM contents, but the underlying
algorithms have been improved over Vista. As a result,
Superfetch now typically prefetches a smaller, but more
relevant volume of data from the disk and prioritizes memory
Overall, our results (from a number of users over weeks)
indicate that disk activity due to Superfetch is
significantly lower in Windows7 compared to Vista while
system responsiveness is much improved due to fewer hard
page faults from the pagefile and other files."
Mehmet Iyigun - Principal Development Lead at Microsoft
To Disable Superfetch simply disable the service:
Press the Windows
keys > type services.msc
> double-click on
service > set Startup type
then Stop the service or
You need more physical memory
Not needed if you have enough memory
- a quick way to add additional memory to your system by
using an external USB flash drive or flash card.
ReadyBoost is not:
- a replacement for an adequate amount of system memory.
- a replacement for the page file (it works in tandem with
Windows 7 features - ReadyBoost
How Do You Use It?
Plug in a USB flash drive of flash card > Open up Computer >
right-click on the drive that you want to use and choose
> click the ReadyBoos
t tab > click
Use this device
> optionally choose how much of the
device to use.
*tip - Use a USB port in the back of your computer. Yep, I
broke a drive sticking out of the front when I bumped into
Microsoft - Turn ReadyBoost on or off for a storage device
(with instructional video)