Just D. said:
Hello,
Whatever I set it uses around 300MB of swap with a medium to hard load
now.
Hi "Just D.",
Mine is currently 224MB with a light load of 27 processes. (I'm writing this
offline.) I have 1GB RAM, with a 3Ghz Pentium 4 CPU. (WinXP-pro-SP3.) Out of
the box, the pagefile was set to Minimum 1524MB, and Maximum 3048MB. The
highest that it has ever gone is about 343MB. The minimum was apparently
based on the standard rule of thumb of making your pagefile 1.5 times larger
than the physical RAM. The maximum is double the minimum, but the actual
pagefile.sys file itself was set up with the minimum size in continguous
clusters. (It is normal for "pagefile.sys" to have 1 fragment.)
I was playing with that many years ago. If I disable swap having enough
memory at the same time some apps simply refuse to start. For example
Adobe Photoshop Elements can't work without virtual memory. That's studid
because even if one has a lot of memory he's stuck here.
First, disabling the paging file does not eliminate virtual memory, since
there will still be a hidden (minimum) 2MB file on the system drive.
Technically, according to the Windows XP Help (Glossary: Paging File) Topic:
"The paging file and physical memory, or RAM, comprise virtual memory."
Of course when most people use the term Virtual Memory, they only mean the
disk-based part. I assume that graphics programs need a lot more virtual
memory than is obvious because of the need to store complete information to
"Undo" editing changes and such like things. (I undo a lot!
Almost always do when possible. It's on its own now, NTFS, 64KB clusters
to provide a better speed. Can't use a separate controller because it's
laptop with obviously limited hardware.
The "speed" may be an illusion. Yes, with 64KB clusters there would be fewer
clusters for both Windows and the MFT (Master File Table) to keep track of,
and therefore electronic transfer of information would be quicker. (And less
possibility of fragmentation with large clusters.) However, the drive still
has to read or write to the individual 512-byte sectors, with a fixed RPM
rotation rate and fixed seek time for the mechanical read/write arm.
Depending where the page file partition is physically located, relative to
the location of the primary system and program files, you may end up with
slower performance while multi-tasking with a lot of page swaps swinging the
head between two widely separated locations in partitions on the same
physical drive. A pagefile on a separate physical drive that was not in
competition with action on the system drive could be faster, (if it is not
on an older slower drive.
Another wrinkle is the way Windows sets up the location of the pagefile on
the volume in the first place, placing it widely separated from the initial
system files. The outermost tracks have the highest number of sectors per
track and therefore the fastest access times, and Windows XP is better than
previous versions because it will move frequently used files closer to the
beginning of the drive to improve access speed, (and it uses prefetch to
speed things up also,) but it does not position the pagefile all that close
to the beginning of the drive near the fastest outermost track.
Another problem I noticed with another computer here, (WinXP-home-SP3,)
with an 83.2GB drive, with a hidden recovery partition, is that the 2.01GB
recovery partition is the first on the drive, so the beginning of the main
80GB partition does not start at the outermost track to begin with. That
computer has 256MB RAM, but the (right-click on My Computer) System
Properties shows it as only 224MB RAM. Both minimum and maximum custom
pagefile were pre-set to 672MB (~3 times RAM size) and elsewhere I noticed
that the reserved (contiguous clusters) pagefile space was 879.66MB.
Another interesting thing with that computer was after installing Avast!
antivirus, I pressed alt+ctrl+del to activate Task Manager with the
Performance tab with the CPU usage and PF usage graphs, and then activated
the full antivirus scan. The CPU usage immediately max'd out at 100% for
more than a minute with occasional downward spikes a few percent less. The
most amazing thing was the PF usage graph, which is ordinarily flat-lined
near the bottom, it became frantic and started jumping up and down like
wild. (Peak 532MB) I assume Avast! was examining every little process in
memory, aggressively swapping pages to see if any viruses or other malware
were active. ("There's a new Sheriff in town!"
The most important thing to remember is that, although the word "disk" in
the term Hard Disk Drive is singular, most desktop computer drives actually
have from 1 to 4 platters inside with 2 heads per platter. That previously
mentioned 83.2GB drive has 1 platter with 2 heads, so there is a 2nd
outermost track area on the 2nd side of the platter where a small pagefile
partition could be set up on the fast track - simply position the partition
slightly past the mid point of the whole drive space. (You would not want
part of the pagefile on the slow inner track of the first side, and part on
the outer track of the 2nd side. Talk about disk chatter thrashing!
Keep in mind also that with NTFS format, the MFT is the first file put on
the partition, and there is a 12.5% space reserved for the MFT Zone on the
partition, so allow maybe an extra 20% more than the maximum pagefile size
for the partition size. The computer I'm currently using to post this
message has a 250GB drive with 2 platters and 4 heads, so it has 4 surfaces
with outermost fast tracks. The drives in both computers are 3.5 inch form
factor (with 3.74 inch platters) and the circumference of the outermost
track is more than 2 times longer, with more than 2 times as many sectors as
the innermost track. That means disk read speeds are generally more than
twice as fast on the outer tracks than the inner ones.
I'm guessing that your laptop probably has a low profile 2.5 inch HDD, so it
would have a shorter distance for the read/write head to move between the
innermost and outermost tracks. Using the 1.5x rule, with 3.24GB RAM, you
would need a minimum (initial) pagefile of 4.86GB, in at least a 6GB
partition. You should be able to set the maximum the same as the minimum
initial size. How big is your internal drive anyway?
BTW: You appear to be using Outlook Express with Avast! antivirus checking
your outgoing messages. Outlook Express sometimes malfunctions when a/v
scans messages. You might want to drop over to the OutlookExpress newsgroup
and learn more about OE quirks, and check out these other links here:
news://msnews.microsoft.com/microsoft.public.outlookexpress.general
http://www.oehelp.com/OETips.aspx
Why you don't need your anti-virus to scan your email
http://thundercloud.net/infoave/tutorials/email-scanning/index.htm
(Be happy! Be VERY happy!
--Richard
- - -
BONUS SECTION: Virtual Memory FAQtoids
For those who don't know where Virtual Memory settings are located:
Right-click My Computer and choose Properties for "System Properties".
(Or hold Windows-Logo key down and press Pause/Break)
Click "Advanced" tab. - In Performance section, click "Settings" button.
Click "Advanced" tab. - In Virtual memory section, click "Change" button.
(Right-click on various items and click "What's This" for help info.)
Virtual Memory Best Practices:
• For best performance, set the initial size to not less than the
recommended size under Total paging file size for all drives. The
recommended size is equivalent to 1.5 times the amount of RAM on your
system.
• If you decrease the size of either the minimum or maximum page file
settings, you must restart your computer to see the effects of those
changes. Increases generally do not require a restart.
• Usually, you should leave the paging file at its recommended size,
although you might increase its size if you routinely use programs that
require a lot of memory.
• To delete a paging file, set both initial size and maximum size to zero.
("Microsoft strongly recommends that you do not disable the paging file.")
Managing computer memory:
When your computer is running low on random access memory (RAM) and more is
needed to complete your current task, Windows uses hard drive space to
simulate system RAM. In Windows, this is known as virtual memory, and often
called the pagefile. This is similar to the UNIX swapfile. The default size
of the virtual memory pagefile (appropriately named Pagefile.sys) created
during installation is 1.5 times the amount of RAM on your computer.
You can optimize virtual memory use by dividing the space between multiple
drives and by removing it from slower or heavily accessed drives. To best
optimize your virtual memory space, divide it across as many physical hard
drives as possible.
When selecting drives, keep the following guidelines in mind:
• Try to avoid having a pagefile on the same drive as the system files.
• Avoid putting a pagefile on a fault-tolerant drive, such as a mirrored
volume or a RAID-5 volume. Pagefiles do not need fault-tolerance, and some
fault-tolerant systems are slow because they write data to multiple
locations.
• Do not place multiple pagefiles on different partitions on the same
physical disk drive.
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