J
Jaap Telschouw
I have Windows XP Pro and two gigs of RAM. Do I still need a page file?
Thanks for your reply
Thanks for your reply
G
GT
Jaap Telschouw said:
You never actually 'need' a page file, it just prevents applications /
windows from crashing / hanging when windows runs out of RAM.
I have 1.5GB RAM and I have my page file turned off. This makes things run
faster as everything loaded is in RAM and never swapped out to hard disk.
Beware, though if you use memory intensive applications and the RAM becomes
full, either the application or Windows will crash.
R
Rod Speed
Jaap Telschouw said:
Yes, its safer to have one which doesnt get used much at all.
XP can be a little stupid with no page file at all.
K
kony
It depends on your specific use of the system. Typically
applications allocate memory they won't ever use, only some
portion of it is ever needed, but must be able to allocate
it anyway. If what you run (total of all apps/etc), never
had need to allocate more than the physical memory installed
in the system then you could run without a pagefile.
If the system use/jobs are non-critical you can just turn it
off and see how it goes, but the moment you have an out of
memory related error, it's time to re-enable pagefile and
check that the problem went away in the same scenario.
Some apps make more efficient use of memory than others too
(for same tasks), so if the goal was improving performance
there are more ways to get there than just disabling
pagefile.
Since most people buy large(r) amounts of memory in
anticipation of running larger jobs rather than to be able
to disable the pagefile, most people would not be able to
disable pagefile without some issues... but it is possible
to run fine without one, given sufficient physical memory.
A
Alex Mizrahi
(message (Hello 'GT)
(you :wrote
n '(Thu, 18 Jan 2007 17:37:39 -0000))
(
G> I have 1.5GB RAM and I have my page file turned off. This makes things
G> run faster as everything loaded is in RAM and never swapped out to hard
G> disk.
this is not really true..
there are pages in memory that are loaded from EXE and DLL files, windows in
some cases can forget about them -- replace those pages by file cache, for
example, and they will be read back later.
if you're using file system very intensively, you can still see some page
faults (and delays) of applications loading back..
you can see this in task manager, if you enabled 'page faults' column, does
it say 0 for all columns?
page file is for pages that are allocated in memory and not backed by some
file. actually, i think there are pages that are allocated, but never used,
so some small amount of paging files can speedup things -- there will be
more place for caches..
i have 2 GB of RAM and have some small page files. i believe it's more
optimal, but i can't be sure..
G> Beware, though if you use memory intensive applications and the RAM
G> becomes full, either the application or Windows will crash.
it's very unlinkely for windows to crash. memory allocation just fails, and
actually application can handle this gracefully.
btw there's one more reason to keep page file size at minimum -- some
applications erroneosly allocate tons of RAM, and with large pagefile
swapping make system non-responsible. with less or no pagefile, those
application will simply honestly report failure..
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
(you :wrote
n '(Thu, 18 Jan 2007 17:37:39 -0000))(
G> I have 1.5GB RAM and I have my page file turned off. This makes things
G> run faster as everything loaded is in RAM and never swapped out to hard
G> disk.
this is not really true..
there are pages in memory that are loaded from EXE and DLL files, windows in
some cases can forget about them -- replace those pages by file cache, for
example, and they will be read back later.
if you're using file system very intensively, you can still see some page
faults (and delays) of applications loading back..
you can see this in task manager, if you enabled 'page faults' column, does
it say 0 for all columns?
page file is for pages that are allocated in memory and not backed by some
file. actually, i think there are pages that are allocated, but never used,
so some small amount of paging files can speedup things -- there will be
more place for caches..
i have 2 GB of RAM and have some small page files. i believe it's more
optimal, but i can't be sure..
G> Beware, though if you use memory intensive applications and the RAM
G> becomes full, either the application or Windows will crash.
it's very unlinkely for windows to crash. memory allocation just fails, and
actually application can handle this gracefully.
btw there's one more reason to keep page file size at minimum -- some
applications erroneosly allocate tons of RAM, and with large pagefile
swapping make system non-responsible. with less or no pagefile, those
application will simply honestly report failure..
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
K
kony
(message (Hello 'GT)
(you :wrote
(
G> I have 1.5GB RAM and I have my page file turned off. This makes things
G> run faster as everything loaded is in RAM and never swapped out to hard
G> disk.
this is not really true..
there are pages in memory that are loaded from EXE and DLL files, windows in
some cases can forget about them -- replace those pages by file cache, for
example, and they will be read back later.
if you're using file system very intensively, you can still see some page
faults (and delays) of applications loading back..
you can see this in task manager, if you enabled 'page faults' column, does
it say 0 for all columns?
page file is for pages that are allocated in memory and not backed by some
file. actually, i think there are pages that are allocated, but never used,
so some small amount of paging files can speedup things -- there will be
more place for caches..
No, pages allocated but never used will not matter, a small
amount of paging does NOT speedup anything. The system
either has enough (real) memory that it doesn't have to page
out (which is ALWAYS faster "IF" the use allows, if it
doesn't require too much memory), or it doesn't have enough
memory, in which case you may have faults, errors, but we
can ignore the error conditions with the simple concept of
"don't configure a system such that it has them".
If the total amount of allocated memory is beyond 2GB, yes
it is more optimal. If the total amount is below 2GB, it
may depend on how much of a benefit you would see from
having a larger filecache (IF you adjust Windows memory
management to have one, this is not a default installation
condition), it is quite possible the larger filecache
reduces rereads from HDD, more than the I/O to HDD from
slight pagefile use. In the end, the goal is still the
same- based on the specific uses of the system, to minimize
access to the HDD.
If you're going to have a pagefile active, it should be
large enough to handle the entire memory allocation from
applications. Allocated memory that isn't used is not
going to be so much of an undue burden on the system, but I
suppose it does depend on exactly what the app is trying to
do, if it is excessively buggy then the solution is to
replace the app.
A
Alex Mizrahi
(message (Hello 'kony)
(you :wroten '(Thu, 18 Jan 2007 16:23:14 -0500))
(
k> No, pages allocated but never used will not matter, a small
k> amount of paging does NOT speedup anything. The system
k> either has enough (real) memory that it doesn't have to page
k> out (which is ALWAYS faster "IF" the use allows, if it
k> doesn't require too much memory),
it might be true if i run a single application cosuming gigabytes of RAM,
but usage patterns on modern desktop computers are not like that.
i have lots of applications running (74 processes for 2 users), and i don't
need all the processes all the time, certainly. i'm even running two OSes
simultaneously -- Linux in vmware, but i'm working with that Linux from time
to time.
so, i think they'll better be swapped out. as i've said, if some active
process will need more RAM, or if some file operations will need be cached,
Windows will swap out that processes anyway -- but it will swap out it's DLL
and EXE pages if it cannot swap allocated memory to pagefile.
RAM is just a cache for data -- some data is backed by files (executable or
filemappings), some is backed by pagefiles, and some will be not backed by
anything. OS might optimize better when it has flexibility to swap out some
allocated memory that is not used to pagefile. certainly, OS might be wrong
in it's optimizations, so it's questionable..
if you disable pagefile, you give priority to data that is explicitly
allocated by applications that is not backed by anything -- so it's not
swapped even if it's not used because there's no place for it. at same time
some data that is more-or-less actively used -- for example, file cache that
caches filesystem structure MFT -- can be swapped out.
??>> i have 2 GB of RAM and have some small page files. i believe it's more
??>> optimal, but i can't be sure..
k> If the total amount of allocated memory is beyond 2GB, yes
k> it is more optimal. If the total amount is below 2GB, it
k> may depend on how much of a benefit you would see from
k> having a larger filecache (IF you adjust Windows memory
k> management to have one, this is not a default installation
k> condition), it is quite possible the larger filecache
k> reduces rereads from HDD, more than the I/O to HDD from
k> slight pagefile use. In the end, the goal is still the
k> same- based on the specific uses of the system, to minimize
k> access to the HDD.
??>> it's very unlinkely for windows to crash. memory allocation just
??>> fails, and actually application can handle this gracefully. btw
??>> there's one more reason to keep page file size at minimum -- some
??>> applications erroneosly allocate tons of RAM, and with large pagefile
??>> swapping make system non-responsible. with less or no pagefile, those
??>> application will simply honestly report failure..
k> If you're going to have a pagefile active, it should be
k> large enough to handle the entire memory allocation from
k> applications.
why?
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
(you :wrote
n '(Thu, 18 Jan 2007 16:23:14 -0500))(
k> No, pages allocated but never used will not matter, a small
k> amount of paging does NOT speedup anything. The system
k> either has enough (real) memory that it doesn't have to page
k> out (which is ALWAYS faster "IF" the use allows, if it
k> doesn't require too much memory),
it might be true if i run a single application cosuming gigabytes of RAM,
but usage patterns on modern desktop computers are not like that.
i have lots of applications running (74 processes for 2 users), and i don't
need all the processes all the time, certainly. i'm even running two OSes
simultaneously -- Linux in vmware, but i'm working with that Linux from time
to time.
so, i think they'll better be swapped out. as i've said, if some active
process will need more RAM, or if some file operations will need be cached,
Windows will swap out that processes anyway -- but it will swap out it's DLL
and EXE pages if it cannot swap allocated memory to pagefile.
RAM is just a cache for data -- some data is backed by files (executable or
filemappings), some is backed by pagefiles, and some will be not backed by
anything. OS might optimize better when it has flexibility to swap out some
allocated memory that is not used to pagefile. certainly, OS might be wrong
in it's optimizations, so it's questionable..
if you disable pagefile, you give priority to data that is explicitly
allocated by applications that is not backed by anything -- so it's not
swapped even if it's not used because there's no place for it. at same time
some data that is more-or-less actively used -- for example, file cache that
caches filesystem structure MFT -- can be swapped out.
??>> i have 2 GB of RAM and have some small page files. i believe it's more
??>> optimal, but i can't be sure..
k> If the total amount of allocated memory is beyond 2GB, yes
k> it is more optimal. If the total amount is below 2GB, it
k> may depend on how much of a benefit you would see from
k> having a larger filecache (IF you adjust Windows memory
k> management to have one, this is not a default installation
k> condition), it is quite possible the larger filecache
k> reduces rereads from HDD, more than the I/O to HDD from
k> slight pagefile use. In the end, the goal is still the
k> same- based on the specific uses of the system, to minimize
k> access to the HDD.
??>> it's very unlinkely for windows to crash. memory allocation just
??>> fails, and actually application can handle this gracefully. btw
??>> there's one more reason to keep page file size at minimum -- some
??>> applications erroneosly allocate tons of RAM, and with large pagefile
??>> swapping make system non-responsible. with less or no pagefile, those
??>> application will simply honestly report failure..
k> If you're going to have a pagefile active, it should be
k> large enough to handle the entire memory allocation from
k> applications.
why?
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
K
kony
(message (Hello 'kony)
(you :wrote
(
k> No, pages allocated but never used will not matter, a small
k> amount of paging does NOT speedup anything. The system
k> either has enough (real) memory that it doesn't have to page
k> out (which is ALWAYS faster "IF" the use allows, if it
k> doesn't require too much memory),
it might be true if i run a single application cosuming gigabytes of RAM,
but usage patterns on modern desktop computers are not like that.
Wrong. Usage patterns do not change it and multiple apps
merely have additive memory load which is still weighed
against what the physical memory can support, or can't.
If there is enough physical memory, enabling a pagefile will
ALWAYS, no matter what other variable, be slower. For the
(nonspecific and thus unprovable) "usage patterns on modern
desktop", it could easily be that there is not enough
physical memory - hence why a pagefile is enabled by
default. Only the user can determine that it isn't needed.
IF you don't have enough physical memory to accomdate all
the rest without swapping, yes. That's not same as having
enough and paging it out for no good reason.
It is true that some data is needed later, or more
frequently, and some isn't. That does not change the fact
that swapping out data is going to be slower if there was no
other use for remaining physical memory. You are
arbitrarily presuming there would be, and indeed sometimes
there is, but that is not the same as a random idea about it
being faster to page out without the specific situation of
having insufficient physical memory to hold it all.
Because that's the whole point of a pagefile, to virtually
provide memory that's not there, not to cause the app to not
have enough even WITH it. Allocation that isn't used is not
a bad thing, it was that it used the HDD at all that causes
the significant performance penalty, even worse when the
system has only one HDD in it as many do.
R
Rod Speed
Wrong with an OS that has enough of a clue to not use it
unless its necessary because there isnt enough physical memory.
And even with one that isnt smart enough to always do that,
you havent established that what minimal use of the pagefile
it does do when there is enough physical memory does slow
things down any anyway, most obviously when what minimal
use it does make of the page file is in the background etc.
Wrong, the OS obviously can.
Pity about when the pagefile is just used to provide
faster access to the read only files on the hard drive.
Not if that is done in the background and its never used from the file.
You are arbitrarily presuming that an OS which does minimally
use a page file when there is enough physical ram, that that
minimal use of the page file has any effect on the speed of ops.
You dont know that.
It isnt the ENTIRE MEMORY ALLOCATION FROM THE APPS
that matters, its the excess over the physical memory that matters.
It can be speed wise if that page file space has to be allocated and is never used.
In spades when you have chosen to run without a page file.
ONLY if that allocated memory is ever actually used.
In spades.
A
Alex Mizrahi
(message (Hello 'kony)
(you :wroten '(Thu, 18 Jan 2007 19:51:03 -0500))
(
k> If there is enough physical memory, enabling a pagefile will
k> ALWAYS, no matter what other variable, be slower.
how do you measure 'enough' or 'not enough' memory?
i've already said you, that RAM is used as cache for files and filesystem
structures.
thus, it's not possible to say if it's enough or not -- just, with more RAM
it would be faster, with less it would be slower.
if i'm doing some intensive file operations, (for example, compilation of
large C++ project), i'd like as much file cache be used as possible. at same
time, i don't care about other applications being in RAM -- i'd prefer them
to be swapped out, to give more RAM to file cache. compilation can go for 10
minutes, in some cases of extra large project for hours. additional file
cache might significantly improve performance.
yes, IDE, firefox and other stuff will need to be swapped back after that,
but i think i won't mind some three-second delay, if that helped to speed up
thing. (i'd say that this delay is inevitable -- windows can 'forget' about
EXEs and DLLs being loaded in favour of file cache).
yes, certainly getting more RAM would help. but if 1 GB RAM + swap will give
me aprox same performace as 2 GB RAM -- why should i pay more?
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
(you :wrote
n '(Thu, 18 Jan 2007 19:51:03 -0500))(
k> If there is enough physical memory, enabling a pagefile will
k> ALWAYS, no matter what other variable, be slower.
how do you measure 'enough' or 'not enough' memory?
i've already said you, that RAM is used as cache for files and filesystem
structures.
thus, it's not possible to say if it's enough or not -- just, with more RAM
it would be faster, with less it would be slower.
if i'm doing some intensive file operations, (for example, compilation of
large C++ project), i'd like as much file cache be used as possible. at same
time, i don't care about other applications being in RAM -- i'd prefer them
to be swapped out, to give more RAM to file cache. compilation can go for 10
minutes, in some cases of extra large project for hours. additional file
cache might significantly improve performance.
yes, IDE, firefox and other stuff will need to be swapped back after that,
but i think i won't mind some three-second delay, if that helped to speed up
thing. (i'd say that this delay is inevitable -- windows can 'forget' about
EXEs and DLLs being loaded in favour of file cache).
yes, certainly getting more RAM would help. but if 1 GB RAM + swap will give
me aprox same performace as 2 GB RAM -- why should i pay more?
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
G
GT
Rod Speed said:
True, but windows does not fall in the category you describe - it
automatically loads itself into RAM, then swaps out parts to the swap file
without question.
In the control panel you can set the minimum and maximum size for the
swapfile. These settings do indicate to windows the smallest amount to use
if the RAM is not full, it simply says the minimum size that the file will
be. This avoids the swapfile becoming fragmented across the disk. Before
setting the virtual memory size, I would recommend turning off virtual
memory completely, rebooting, defragmenting the hard disk, then setting the
minimum and maximum values to the same amount, so that the swapfile is
configured in one large contiguous block on the disk and will never grow and
shrink and therefore cannot become defragmented. Of course, this is my
advice to someone with less RAM than the applications they use can ever
need. If you have enough RAM - turn it off and things will be faster,
quieter and more responsive.
Wrong, some OS's can, but windows doesn't.
Who told you that gem?!?
But loading from virtual memory IS using something from a file - its just
not in the original place on the hard disk!
No, we are stating a fact - swapping files between physical RAM and the
slower hard disk (virtual memory) has a performance impact on the system.
Also, like I said above - the minimum setting for the swapfile is not an
indication of how much windows will use as a minimum, just the smallest size
the swapfile is allowed to be.
Yes we do.
Perhaps you could stretch to more than 1 word in your reasoning here - the
standard is for virtual memory to be 100%-150% the size of the RAM
You proove our point - it is used all the time by Windows, whether it needs
it or not!
G
GT
Alex Mizrahi said:(message (Hello 'kony)
(you :wrote
(
k> If there is enough physical memory, enabling a pagefile will
k> ALWAYS, no matter what other variable, be slower.
how do you measure 'enough' or 'not enough' memory?
I would recommend opening all the applications you will ever use one at a
time and in typical configurations and load a few files, use things for a
while, then check with the of task manager to see what percentage of total
memory you managed to use. If this is anywhere near the physical amount of
RAM, then leave a swapfile in place. If nowhere near the amount of physical
RAM (less than 75% perfaps) then turn off the swapfile.
I work from home as a C++ developer! I have my swapfile turned off in order
to improve performance. If I am in a position to not care about other
applications, then I close them, but typically I have Explorer, Outlook, MS
Visual Studio (x2), IE, Word and Excel open in my 1.5GB RAM and my memory
useage rarely goes above 0.5GB even at peak times. When I compile our large
project (23 different project solutions which compile over 15 minutes in
batch mode), the hard disk never stops thrashing as it loads small class
files from disk, compiles them and saves them as object files, which are
then reloaded and linked to form 23 EXEs and DLLs. With the added
complication of swapping files to and from a virtual memory file at the same
time as all this other disk activity, performance would be hit
significantly.
And how long does it take to press the button on your shortcut bar to open
these applications again - given that they have been cached by windows -
probably somewhere in the region of 2 - 3 seconds!!
Fair question, but based on a false premise - the answer is that 2GB of RAM
will potentially give you much better performance than 1GB RAM + swapfile.
The performance increase will however depend greatly on what you are doing
and how much more than 1GB of RAM your day-to-day use requires and I suspect
that you probably don't use much more than 1GB RAM.
Turn the update speed to low on your task manager and occasionally make the
performance tab full screen and check the page file useage history - this is
actually memory usage, not pagefile usage!
G
GT
kony said:
Interesting - how do I turn up the cache size for windows please? This would
be very useful for my work.
G
GT
Alex Mizrahi said:(message (Hello 'GT)
(you :wrote
(
G> I have 1.5GB RAM and I have my page file turned off. This makes things
G> run faster as everything loaded is in RAM and never swapped out to hard
G> disk.
this is not really true..
there are pages in memory that are loaded from EXE and DLL files, windows
in some cases can forget about them -- replace those pages by file cache,
for example, and they will be read back later.
if you're using file system very intensively, you can still see some page
faults (and delays) of applications loading back..
you can see this in task manager, if you enabled 'page faults' column,
does it say 0 for all columns?
38 processes at the moment. Been running system for 1.5 hours. I'm using MS
Visual Studio, Word, Excel, Outlook and Outlook express, notepad. 0 page
faults across the board.
G
GT
Rod Speed said:
Agreed - it is safer, but unfortunately windows will use it if it is there,
whether it needs it or not, so your system will see a performance
reduction,. I suspect that any PC with 2GB of RAM is probably powerful
enough to absorb the performance hit and the user won't even notice in day
to day use. Its only noticable if you use some application that requires
disk access and is impeeded by virtual memory activity.
Not in my experience over the last 2 years - XP works much faster and more
efficiently with it turned off.
G
GT
[snip]
Addendum - I've just remembered the data at the bottom of task manager -
bottom left box (commit charge). The Peak figure is the highest amount of
memory that has been required since you opened task manager.
Addendum - I've just remembered the data at the bottom of task manager -
bottom left box (commit charge). The Peak figure is the highest amount of
memory that has been required since you opened task manager.
G
GT
GT said:
OOPS - I missed a word out above. Second sentence should read - "These
settings do NOT indicate to windows..."
K
kony
I take it you either never used WINDOWS or never bothered
to monitor pagefile activity.
That's wrong enough I don't know where to start.
Pagefile isn't necessarily any faster than rest of HDD, the
only gain there is if paging unneeded things left more
memory available for a (larger) filecache in physical
memory.
Never suggested it wasn't. The fact remains that it is
possible a use(s) won't have any excess over physical memory
but windows will still have pagefile activity.
K
kony
(message (Hello 'kony)
(you :wrote
(
k> If there is enough physical memory, enabling a pagefile will
k> ALWAYS, no matter what other variable, be slower.
how do you measure 'enough' or 'not enough' memory?
i've already said you, that RAM is used as cache for files and filesystem
structures.
thus, it's not possible to say if it's enough or not -- just, with more RAM
it would be faster, with less it would be slower.
Well windows does monitor this. Hardly impossible.