How does memory management work?

[naf456]

Hello, Nathan here.

Totally in love with TC at the mo. Have my graphics all set up and my sound working.

I'm curious to how TC manages memory , if the root FS is loaded in RAM does that mean all files saved to root FS is loaded in the ram also?

for example I have got xonotic up and running , however chrome saved it to downloads initially - and thats when my RAM usage went through the roof.
I have moved it to the disk I have got TC installed now , and so the ram is much less.

[tinypoodle]

tmpfs (using RAM + swap) is mounted over /.
Any other filesystem can be accessed through its mount point.

[naf456]

Yeah - but the core filesystem is "Virtual" - meaning that it only exists in ram , because on HDD it's actually an archive.

How can you save something to "~/Downloads" on the HDD when it doesn't exist - only in the RAM.
Download Xonotic to RAM lol.

Or does it - is "~/" inflated at boot? ie is it on the HDD? erh... so confused. too early in the morning ^_^

[althalus]

Options:
1. Download everything to an external drive, instead of ~/
2. Use TC's built in backup features
3. Set up a persistent home

Spend some time reading the information on the tinycore website, and on the wiki to find out more. TC is different enough from most other linuxes that the wiki and the website should probably be treated as required reading before getting started.

[tinypoodle]

The content of the initrd cpio archive gets extracted into initramfs (a special instance of tmpfs in case of TC - using shared mem as storage space) at boot time.

[Rich]

Hi naf456
The file system is basically all in RAM, however, not everything that gets attached to the file system has to be RAM
based. For example:
/mnt refers to RAM
/mnt/sda1 refers to RAM
If I execute:

Code: [Select]

mount /mnt/sda1/mnt/sda1 now refers to drive sda1 and anything copied to /mnt/sda1 goes to the root directory of that drive.
If I now execute:

Code: [Select]

umount /mnt/sda1/mnt/sda1 now refers to RAM again and anything copied to /mnt/sda1 goes to RAM.
If you don't wish to setup a persistent home, you could setup a persistent downloads directory instead and have
Chrome default to that directory.

[tinypoodle]

Options:
1. Download everything to an external drive, instead of ~/

Besides from that, it is also a good idea to configure web browsers so they couldn't use huge amounts of tmpfs space for cache etc.
Also, having generous swap space available whenever possible.

[vinnie]

I also have a question of this type:
As is explained in canonically informatic courses the programs before they are executed by the processor are loaded in ram in a load phase.
in tinycore the programs are already installed in ram, then what happens? are loaded again in ram 2 times or not?

[gerald_clark]

The programs are not installed in RAM.  The extensions are loop mounted into the filesystem.  They are then loaded from from disk/flash-drive to RAM for execution.
They may also reside in cache for a while, but that could be flushed at any time.

If you use copy2fs flag or list,  there will be a copy of the extension in the RAM based filesystem, but it will still need to be loaded into RAM for execution.  In this case, there will be 2 copies of a progam in RAM, and temporarily a third temporary copy in cache.  This is a good reason not to use copy2fs on systems without a lot of RAM.

[curaga]

IIRC tmpfs doesn't cause that kind of double copy: http://lkml.indiana.edu/hypermail/linux/kernel/0705.0/0940.html

[gerald_clark]

Thanks.
Corrected:  there will not be a 3rd temporary copy in cache.

[vinnie]

Thanks gerald, concise and comprehensive as usual.
I use the flag copy2fs so I have 2 copies.
A question yet, but copy2fs also has effect on the scm packages?

[naf456]

So to clarify - every program/library/resource loaded into the operating system is loaded into the RAM - so TC is kinda crippled if you want to run something like Photoshop (if it were possible) or some other large program?

I tried to run TCX in a virtual machine with 400MHz CPU cap with 64MB or RAM (simulating that of an old laptop) - it pretty much crashed - which was to be expected - yet with 512MB - Even 256MB of ram it ran fairly stable, albeit slow.

What is also blurry is how the applications get extracted from there squash file system? where are they extracted to, in RAM or on disk?

I'm still researching and learning about Linux and Unices, but I still have tons to learn still.

tonight I'll look through some of the scripts and check out how things tick.

still find it pretty cool playing Xonotic on ultra with no considerable frame rate drops like I get in windows or ubuntu XD

 

[vinnie]

No, they are all copied completely in ram only if you use the flag copy2fs.flg or the command tce-load -ic or a file to specify programs to be copied entirely in RAM.
Otherwise, access is from a mass storage memory.
The main advantage is that you can umount the mass storage memory  if you copied all the extensions in ram (with the flag).

[Rich]

Hi naf456
Maybe some pictures will help?
http://tinycorelinux.net/architecture.html  and  http://tinycorelinux.net/arch_copymode.html