Re: Debian's recommendation for the size of the swap.

[Kenneth Scharf]

For now I probably don't need that much.  But my plans include setting my 
system up as a server for two windows machines, that should increase the 
demands on virtual memory.


Attached is a free run.  (with X, Netscape (reported to need 64M available), 
xterm fvwm95, xconsole running.





---shaul <[EMAIL PROTECTED]> wrote:
>
> > If anyone is taking a survery...
> > My machine also has 64M or ram, and I am using 128M of swap space (I
> > figured with a 5.4GB drive I'd max out the swap partition.)
> > 
> I am curious if that size of swap is realy needed: could you email the 
> results 
> of a free command ?
> 
>   Thank you. 
> 
> 
> 
> 
> 
> 

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foofree
Description: foofree

Partition size technicalities. Re: Debian's recommendation for the size of the swap.

[Christopher Barry]

Pierfrancesco Caci wrote:
[...]
> I've a machine with 64 MB ram, 1 swap partition of about 32 MB (made
> like that when I only had 32 MB ram) 1 swap file of 127 MB (it doesn't
> take 128 MB, you must put something less).
[...]

If you really want to know why this is (probably not), partition sizes
are actually specified in cylinders. It is possible to define partition
boundaries that do not lie on cylinder boundaries, but this can be very
dangerous and most partitioning software only lets you do this with the
'expert options' or something similar.

Most disks have a geometry that is something like  x 255
heads x 16 sectors x 512 bytes per sector. So the size of one cylinder
is going to be 255x16x512, which is 2,088,960 bytes. Thus all of your
partition sizes are going to be multiples of that, and the closest
multiple to 128MB is 127,426,560 bytes.

While not as important with ext2fs Linux and FAT32/Win, it's a good idea
to size your partitions to the closest cylinder that resides under the
power of 2 mark (<31MB, <63MB, <511MB, etc) for minimal cluster sizes
and minimal disk space wastage. Even though newer filesystems like
ext2fs and FAT32 typically use 4k inodes or clusters, if you have 8GB
partitions then there's going to be an incredible amount of clusters or
accounting information and this will lower performance so it's good to
use multiple, smaller partitions anyways for this reason and all the
other reasons for using seperate /var, /tmp, etc. partitions.

Christopher

Re: Debian's recommendation for the size of the swap.

[shaul]

> On Wed, Oct 14, 1998 at 11:34:16PM +0300, shaul wrote:
> > (1) Linux accept up to 128MB for a single swap partition (2) There is (was) 
> > a 
> > rule of thumb to have a swap size as twice as the RAM the machine has (3) 
> > Having more RAM reduces the needs for swap.
> 
> ya konw, i'm a little confused. people say more RAM reduce the needs for swap
> while swap is recommended for double size of RAM ? yeah, newbia i am :-P
> 

[01:30:15 shaul]$ grep -A18 "Your swap partition" /cdrom/install.txt 
  Your swap partition will be used to  provide virtual memory for
  the system and should be between 16 and  128 megabytes in size,
  depending on how  much disk space you  have and how  many large

  programs you want to run.   The old rule of thumb is  that swap
  should be  twice as big  as the amount  of physical memory  you
  have available.  Once  you get past the  32MB of RAM  mark, you
  shouldn't make your  swap partition more  than 1.5 bigger  than
  the amount of RAM.  Linux will not use more than  128 megabytes
  of swap  on a single  swap partition, so  there's no reason  to
  make your  swap partition  larger than that.  However, you  can
  make multiple swap partitions  by hand and edit  /etc/fstab af-
  ter you've installed  to get more  than 128 megabytes  of swap.
  A swap partition is strongly recommended, but  you can do with-

  out one  if you insist,  and if  your system  has more than  16
  megabytes of RAM. If you wish to do this,  please select the Do
  Without a Swap Partition item from the menu.

[01:30:27 shaul]$ 


> > Does all this make sense ?
> > Perhaps Debian should make a small survey among its users about the size of 
> > the swap size they are using ?
> 
> i'm currently use 12M swap with 64M RAM, is it too few ?

Well, IMHO it is too small. 
I wonder, could you send what free reports when your machine runs your "usual" 
apps?

> i feel ugly when open *guash*, and xemacs and netscape opened very slowly. i
> only have 2G hd, and 750M among it is spared for win98 'cause i need its
> support for chinese stuff.

Will it get quicker if you'll create a swap file ?  
> 
> --zhaoway
> 
> >the exactly 9th registerd linux user in counter.li.org<
> 
> 
> -- 
> Unsubscribe?  mail -s unsubscribe [EMAIL PROTECTED] < /dev/null
> 

Re: Debian's recommendation for the size of the swap.

[shaul]

> If anyone is taking a survery...
> My machine also has 64M or ram, and I am using 128M of swap space (I
> figured with a 5.4GB drive I'd max out the swap partition.)
> 
I am curious if that size of swap is realy needed: could you email the results 
of a free command ?

Thank you. 

Re: Debian's recommendation for the size of the swap.

[Kenneth Scharf]

If anyone is taking a survery...
My machine also has 64M or ram, and I am using 128M of swap space (I
figured with a 5.4GB drive I'd max out the swap partition.)



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RE: Debian's recommendation for the size of the swap.

[Person, Rod]

Hey all,

I have to admit to ignorance on this subject, never spent much time
worrying about swap file and VM. Never much interested me. 

But, for reading this discussion I have a question. I have 12M of Ram
and 12M of Swap (could afford more only have 250M). Now if I have a
program that requires 20M of Ram to run, then With my specs it should
run? I'm I right on this one?

Rod.

> --
> From: [EMAIL PROTECTED]:[EMAIL PROTECTED]
> Sent: Thursday, October 15, 1998 1:51 AM
> To:   debian-user@lists.debian.org
> Subject:  Re: Debian's recommendation for the size of the swap.
> 
> [EMAIL PROTECTED] wrote:
> > On Wed, Oct 14, 1998 at 11:34:16PM +0300, shaul wrote:
> >> (1) Linux accept up to 128MB for a single swap partition (2) There
> is
> >> (was) a rule of thumb to have a swap size as twice as the RAM the
> >> machine has (3) Having more RAM reduces the needs for swap.
> > 
> > ya konw, i'm a little confused. people say more RAM reduce the needs
> for
> > swap while swap is recommended for double size of RAM ? yeah, newbia
> i
> > am :-P
> 
> That swap must be >= 2*RAM is a common misconception in the Linux
> world.
> On BSD's this is a good rule of thumb, due to a different VM[1]
> subsystem
> design but on Linux only the RAM+swap figure matters.
> 
> The only general rule for swap size is that you should have enough.
> That
> means that RAM+swap should be large enough to run the programs you are
> likely to run at any given time.
> 
> Note, however, that you should always have *some* swap, even if all
> your
> programs will fit in RAM, to allow the kernel to swap out unused pages
> and
> make room for more buffers.  Similarly, you should always have some
> unused
> VM to allow for extraordinary memory requirements and to make room for
> buffers.  Did I mention that buffers are a good thing? :-)
> 
> It is, of course, better to have too much swap space than too little.
> Horrible things will happen if you run out of VM: processes will be
> randomly killed off, the system may crash, etc.
>  
> > i'm currently use 12M swap with 64M RAM, is it too few ? i feel ugly
> > when open *guash*, and xemacs and netscape opened very slowly. i
> only
> > have 2G hd, and 750M among it is spared for win98 'cause i need its
> > support for chinese stuff.
> 
> I would probably add some some swap space, but as I outlined above,
> this
> is a very individual thing.  My box has 64MB RAM + 96MB swap and it
> seems
> quite happy with that configuration.  However, I probably use more VM
> than
> most people...
> 
> [1]  VM = Virtual Memory
> -- 
>/'"`\  zzzZ  | My PGP Public Key is available at:
>   ( - - )   | <http://home1.inet.tele.dk/renehl/>
> --oooO--(_)--Oooo-- 
>  Don't ya just hate it when there's not enough room to fin 
> 

Re: Debian's recommendation for the size of the swap.

[Peter S Galbraith]

> i'm currently use 12M swap with 64M RAM, is it too few ?

Here's what you do:

$ free
 total   used   free sharedbuffers cached
Mem:127660 120980   6680  21636  44904  35608
-/+ buffers/cache:  40468  87192
Swap:25580240  25340

I have 128 MB of RAM.  I'm using all of it but 6.6MB, but I only really
need 40MB for my applications, the rest of the 128MB is caching files
that I have used recently.  The next time I read them, they will already in
RAM and Linux won't access the disk, thus the process will be 10 times
faster.  

I'm  hardly using my swap, and almost never do.
-- 
Peter Galbraith, research scientist  <[EMAIL PROTECTED]>
Maurice Lamontagne Institute, Department of Fisheries and Oceans Canada
P.O. Box 1000, Mont-Joli Qc, G5H 3Z4 Canada. 418-775-0852 FAX: 775-0546
6623'rd GNU/Linux user at the Counter - http://counter.li.org/ 

Re: Debian's recommendation for the size of the swap.

[Helge Hafting]

In <[EMAIL PROTECTED]>, on 10/14/98 
   at 11:34 PM, [EMAIL PROTECTED] (shaul) said:
>that iconifying most of these windows  has little effect on the memory
>usage.
Yes, minimizing a program does not magically make it use less memory. Your
screen may repaint faster though, when there's less to repaint.

>Does all this make sense ?
>Perhaps Debian should make a small survey among its users about the size
>of  the swap size they are using ?
I have 32M ram and 64M of swap on the home machine.
I have seen it use 1.8M of swap when
both running X games and compiling a kernel.  I believe this
will increase when I start using netscape and staroffice. :-)

Helge Hafting












-- 
---
[EMAIL PROTECTED]
---

Re: Debian's recommendation for the size of the swap.

[Rene Hojbjerg Larsen]

[EMAIL PROTECTED] wrote:
> On Wed, Oct 14, 1998 at 11:34:16PM +0300, shaul wrote:
>> (1) Linux accept up to 128MB for a single swap partition (2) There is
>> (was) a rule of thumb to have a swap size as twice as the RAM the
>> machine has (3) Having more RAM reduces the needs for swap.
> 
> ya konw, i'm a little confused. people say more RAM reduce the needs for
> swap while swap is recommended for double size of RAM ? yeah, newbia i
> am :-P

That swap must be >= 2*RAM is a common misconception in the Linux world.
On BSD's this is a good rule of thumb, due to a different VM[1] subsystem
design but on Linux only the RAM+swap figure matters.

The only general rule for swap size is that you should have enough.  That
means that RAM+swap should be large enough to run the programs you are
likely to run at any given time.

Note, however, that you should always have *some* swap, even if all your
programs will fit in RAM, to allow the kernel to swap out unused pages and
make room for more buffers.  Similarly, you should always have some unused
VM to allow for extraordinary memory requirements and to make room for
buffers.  Did I mention that buffers are a good thing? :-)

It is, of course, better to have too much swap space than too little.
Horrible things will happen if you run out of VM: processes will be
randomly killed off, the system may crash, etc.
 
> i'm currently use 12M swap with 64M RAM, is it too few ? i feel ugly
> when open *guash*, and xemacs and netscape opened very slowly. i only
> have 2G hd, and 750M among it is spared for win98 'cause i need its
> support for chinese stuff.

I would probably add some some swap space, but as I outlined above, this
is a very individual thing.  My box has 64MB RAM + 96MB swap and it seems
quite happy with that configuration.  However, I probably use more VM than
most people...

[1]  VM = Virtual Memory
-- 
   /'"`\  zzzZ  | My PGP Public Key is available at:
  ( - - )   | 
--oooO--(_)--Oooo-- 
 Don't ya just hate it when there's not enough room to fin 

Re: Debian's recommendation for the size of the swap.

[zhaoway]

On Wed, Oct 14, 1998 at 11:34:16PM +0300, shaul wrote:
> (1) Linux accept up to 128MB for a single swap partition (2) There is (was) a 
> rule of thumb to have a swap size as twice as the RAM the machine has (3) 
> Having more RAM reduces the needs for swap.

ya konw, i'm a little confused. people say more RAM reduce the needs for swap
while swap is recommended for double size of RAM ? yeah, newbia i am :-P

> Does all this make sense ?
> Perhaps Debian should make a small survey among its users about the size of 
> the swap size they are using ?

i'm currently use 12M swap with 64M RAM, is it too few ?
i feel ugly when open *guash*, and xemacs and netscape opened very slowly. i
only have 2G hd, and 750M among it is spared for win98 'cause i need its
support for chinese stuff.

--zhaoway

>the exactly 9th registerd linux user in counter.li.org<

Re: Debian's recommendation for the size of the swap.

[Pierfrancesco Caci]

[EMAIL PROTECTED] (shaul) writes:

> 3) Resizing disks partitions when someone needs more swap is a problmatic 
> process, and using swap files are not recommended.

why do you say that swap files are not recommended ? I know the're
slower than swap partitions, but I can't see what other problems can exist.



> Perhaps Debian should make a small survey among its users about the size of 
> the swap size they are using ?
> 

I've a machine with 64 MB ram, 1 swap partition of about 32 MB (made
like that when I only had 32 MB ram) 1 swap file of 127 MB (it doesn't
take 128 MB, you must put something less). 
On another machine with only 16 MB ram I have a 127 MB partition and a
127 MB file. The file gets seldom used.

Pf

-- 

---
 Pierfrancesco Caci  | mailto:[EMAIL PROTECTED] - http://gusp.infogroup.it
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 Linux penny 2.1.122 #7 Thu Sep 17 13:56:01 CEST 1998 i586 unknown