devil-linux-develop

[Devil-linux-develop] thinking about ramdisk size as a function of installed ram

[Friedrich L. <fl...@fl...>]

Hi!

I was just thinking about making the size of the ramdisk 
a function of the amount of installed ram. See 
  http://www.fl.priv.at/devil-linux/ramdisk-usage.html
about which numbers came to my mind.

What do you think about that? 

Just don't forget that we use shmfs now so the size of the
ramdisk is always as big as much as devil-linux copied in into 
it. The ramdisk size I'm talking about is the max. size the 
ramdisk can get - a hard limit so to speak. So if you've got 
64 MB of ram and the limit is 40 MB but the actuall used space 
in your ramdisk is 32 MB then you've the other 32 MB for your 
programs.

So the numbers in the graphic are a hard limit for the ramdisk
and a minimum for the amount of available memory.

PS: The StarOffice sheet for this report can be found at
 http://www.fl.priv.at/devil-linux/ramdisk-usage.sdc

Greetings
Friedl

Re: [Devil-linux-develop] thinking about ramdisk size as a function of installed ram

[Heiko Z. <he...@zu...>]

Friedrich Lobenstock wrote:
> Hi!
> 
> I was just thinking about making the size of the ramdisk 
> a function of the amount of installed ram. See 
>   http://www.fl.priv.at/devil-linux/ramdisk-usage.html
> about which numbers came to my mind.
> 
> What do you think about that? 

Good idea, but we should make this a bit more comfortable and intelligent.

Here my 2 cents:

** parameter in /etc/sysconfig/config:
CONFIG_RAMDISK_SIZE=auto | size in MB
So you could specify the maximum size manually or use our script to 
calculate it.
Per default it should be set to "auto".

** more intelligent
The script should also take care about swap space, but should print out 
a warning when he thinks that the system will start swapping.
With this warning, the user would know that he looses performance but 
the system will still function as expected

** RAM usage of programs
We don't only need the size of the programs, we would also need to know 
their ram usage when the program is running.
But I think that's a bit hard, because it really depends on the 
environment and what the user is doing.



-- 

cu
   Heiko

We are Penguin, Resistance is futile!

http://www.devil-linux.org

Re: [Devil-linux-develop] thinking about ramdisk size as a function of installed ram

[Friedrich L. <fl...@fl...>]

On Sat, 23 Mar 2002 09:43, Heiko Zuerker wrote:

> ** parameter in /etc/sysconfig/config:
> CONFIG_RAMDISK_SIZE=auto | size in MB
>
> So you could specify the maximum size manually or use our script to
> calculate it. Per default it should be set to "auto".

Hmmm...don't know how to resize a shmfs. There's no option for that.
Why that, you might ask. The ramdisk get's created and then the config
disk gets read and extracted into it. But what I could think of is
that save_config extracts the CONFIG_RAMDISK_SIZE from
/etc/sysconfig/config and creates a file on the floppy disk eg.
initrd.conf. BTW with this file we could also tell the linuxrc script
in the initrd which scsi driver it should load.


> ** more intelligent
> The script should also take care about swap space, but should print
> out a warning when he thinks that the system will start swapping.
> With this warning, the user would know that he looses performance
> but the system will still function as expected

As a start I would just calculate the ramdisk usage of the base system
and each package, create files PACKAGE-NAME.size with the size value
in it. So the initrd can calculate when it has to stop extracting
packages to the ramdisk because the ramdisk would overflow. With this
method we can leave some space for temp files so the user can at least
change his config files. Because with a ramdisk that has 0 bytes free
the user could destroy his config. Happend to me once, so a simple
passwd command destroyed the /etc/passwd file - not much fun if the
machine is 250 miles away and if you drop the ssh connection.


> ** RAM usage of programs
> We don't only need the size of the programs, we would also need to
> know their ram usage when the program is running. But I think that's
> a bit hard, because it really depends on the environment and what
> the user is doing.

I would leave this task to a eg. php script on the webpage where the
user selects what he want's to use and then the script outputs our
recommendations for his system. (BTW is PHP on www.devil-linux.org
possible?)


-- 
MfG / Regards
Friedrich Lobenstock
____________________________________________________________________
Friedrich Lobenstock         FL226-RIPE             Internetservices
URL: http://www.fl.priv.at/                     Email: fl...@fl...
____________________________________________________________________

Re: [Devil-linux-develop] thinking about ramdisk size as a function of installed ram

[Heiko Z. <he...@zu...>]

Friedrich Lobenstock wrote:
> On Sat, 23 Mar 2002 09:43, Heiko Zuerker wrote:
> 
> 
>>** parameter in /etc/sysconfig/config:
>>CONFIG_RAMDISK_SIZE=auto | size in MB
>>
>>So you could specify the maximum size manually or use our script to
>>calculate it. Per default it should be set to "auto".
>>
> 
> Hmmm...don't know how to resize a shmfs. There's no option for that.
> Why that, you might ask. The ramdisk get's created and then the config
> disk gets read and extracted into it. But what I could think of is
> that save_config extracts the CONFIG_RAMDISK_SIZE from
> /etc/sysconfig/config and creates a file on the floppy disk eg.
> initrd.conf. BTW with this file we could also tell the linuxrc script
> in the initrd which scsi driver it should load.

Yes you would have to extract the file.
I hope that the Linux file cache is good enough, that he doesn't read 
the tar file again, when we unpack the configuration. Otherwise we would 
have to find a better solution, because it takes to long.
We could also go ahead and copy the tar file into the tmp directory and 
work from there.

CONFIG_INITRD_MODULES="list of modules"
I like that idea, this would be an easy and good solution.

>>** more intelligent
>>The script should also take care about swap space, but should print
>>out a warning when he thinks that the system will start swapping.
>>With this warning, the user would know that he looses performance
>>but the system will still function as expected
>>
> 
> As a start I would just calculate the ramdisk usage of the base system
> and each package, create files PACKAGE-NAME.size with the size value
> in it. So the initrd can calculate when it has to stop extracting
> packages to the ramdisk because the ramdisk would overflow. With this
> method we can leave some space for temp files so the user can at least
> change his config files. Because with a ramdisk that has 0 bytes free
> the user could destroy his config. Happend to me once, so a simple
> passwd command destroyed the /etc/passwd file - not much fun if the
> machine is 250 miles away and if you drop the ssh connection

That's ok, we can't have a 100% solution immediately.
The scripts will be improved over time.

> I would leave this task to a eg. php script on the webpage where the
> user selects what he want's to use and then the script outputs our
> recommendations for his system. (BTW is PHP on www.devil-linux.org
> possible?)

Yes, PHP4 with MySQL

-- 

cu
   Heiko

We are Penguin, Resistance is futile!

http://www.devil-linux.org