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thebigslide
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Joined: 23 Dec 2004
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Location: under a car or on top of a keyboard
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 Posted: Fri Feb 18, 2005 5:16 am Post subject: HOWTO: Mount / in RAM and load apps instantly |
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I figured this out based on this post:
So you want to mount / in RAM for a super-speedy system?
Here's what you need to make your gentoo FLY
/usr must be on it's own partition
/home must be on it's own partition if it's large or you use it for storage
/root must be on it's own partition if you're putting anything big in it
/var on it's own partition (so we don't fill up the RAM drive with logs/portage cache)
an empty directory called /newroot
You must have a partition to store the tarballs on (I use the same partition that ends up being /root) and it can't be /usr.
Maybe use the partition that was / during the install
computer must have a spare 176MB of RAM or so.
(Depends how much you want to load into RAM)
You need to have ramdisk, initial ramdisk, loopback device support in the kernel, not as modules.
These choices can be found under block devices, which is under device drivers.
The amount of performance boost in order of magnitude, by which is loaded into RAM seems to be
/usr/lib
/lib
/usr/bin
/bin
/usr/sbin & /sbin
Step 1
Install as normal
Step 2
generate the tarballs that will populate our RAM drives
put this in /sbin so you can run it should you update your system (make sure STORE is mounted first if applicable!):
| Code: |
echo /sbin/update-balls >> /etc/conf.d/local.stop
chmod +x /sbin/update-balls
cat /sbin/update-balls
##############
#!/bin/sh
CURRDIR=`/bin/pwd`
STORE="root"
cd /
#Exclude anything that's on it's own partition here
tar cfp ${STORE}/fs.tar * --exclude=usr/* --exclude=root/* --exclude=home/* \
--exclude=proc/* --exclude=sys/* --exclude=tmp/* --exclude=var/* \
--exclude=opt/*
cd /usr/
# rm -fr /usr/bin /usr/sbin /usr/lib
# cp -a /usr/.bin /usr/bin
# cp -a /usr/.sbin /usr/sbin
# cp -a /usr/.lib /usr/lib
cd bin && tar cfp /${STORE}/usr_bin.tar *
cd ../sbin && tar cfp /${STORE}/usr_sbin.tar *
cd ../lib && tar cfp /${STORE}/usr_lib.tar *
# rm -fr /usr/bin /usr/sbin /usr/lib
# mkdir /usr/bin /usr/sbin /usr/lib
cd $CURRDIR
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Step 3
Now we have to make an initrd to perform the population of our RAM drive before we load init:
| Code: |
mount /boot #If necessary
touch /boot/initrd
dd if=/dev/zero of=/boot/initrd bs=1024k count=8
losetup /dev/loop0 /boot/initrd
mke2fs /dev/loop0
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Now we have loop0 mounted as the initrd. Time to populate it:
| Code: |
mkdir /mnt/initrd
mount /dev/loop0 /mnt/initrd
cd /mnt/initrd
mkdir etc dev lib bin proc new store
touch linuxrc etc/mtab etc/fstab
chmod +x linuxrc
for I in sh cat mount umount mkdir chroot tar; do cp /bin/$I bin/; done
cp /sbin/pivot_root bin/
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We need a /newroot directory to hold the initrd after the system's booted.
Now we have to copy the libraries that each of these binaries needs. You can determine this a la:
| Code: |
ldd /bin/sh
linux-gate.so.1 => (0xffffe000)
libdl.so.2 => /lib/libdl.so.2 (0xb7fe2000)
libc.so.6 => /lib/tls/libc.so.6 (0xb7eca000)
/lib/ld-linux.so.2 (0xb7feb000)
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means we need /lib/libdl.so.2 /lib/tls/libc.so.6, lib/ld-linux.so.2
Here's what I needed in total:
| Code: |
ls -R lib
lib:
ld-linux.so.2 libblkid.so.1 libdl.so.2 libuuid.so.1 tls
lib/tls:
libc.so.6 libpthread.so.0 librt.so.1
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Please check each of your binaries in case you need something I don't. Then we need to write the linuxrc script that does the dirty work:
| Code: |
cat /mnt/initrd/linuxrc
################
#!/bin/sh
export PATH=/bin
STOREDEV=/dev/hda10
STORE=/store
ROOTSIZE=128m
# Get kernel CMDLINE
mount -t proc none /proc
CMDLINE=`cat /proc/cmdline`
umount /proc
mount $STOREDEV $STORE
# Mount root and create read-write directories
mount -t tmpfs -o size=$ROOTSIZE none /new/ > /dev/null 2>&1
cd /new/ && tar xpf $STORE/fs.tar > /dev/null 2>&1
umount $STOREDEV
# Pivot root and start real init
cd /new
pivot_root . newroot
exec chroot . /bin/sh <<- EOF >dev/console 2>&1
exec /sbin/init ${CMDLINE}
EOF
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Once that's done, we need to make the device nodes that this will use:
| Code: |
mknod /mnt/initrd/dev/console c 5 1
mknod /mnt/initrd/dev/null c 1 3
mknod /mnt/initrd/dev/hda b 3 0
mknod /mnt/initrd/dev/hda4 b 3 4
mknod /mnt/initrd/dev/hda10 b 3 10
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You only need the nodes for the mounts that the linuxrc script uses (see /usr/src/linux/Documentation/devices.txt)
And that's it for the initrd
Step 4
Modify /etc/init.d/localmount | Code: | start() {
USRBINSIZE=32m
USRSBINSIZE=2m
USRLIBSIZE=256m
# Mount local filesystems in /etc/fstab.
ebegin "Mounting local filesystems"
mount -at nocoda,nonfs,noproc,noncpfs,nosmbfs,noshm >/dev/null
eend $? "Some local filesystem failed to mount"
ebegin "Mounting RAM filesystems"
mount -t tmpfs -o size=$USRBINSIZE none /usr/bin > /dev/null 2>&1
mount -t tmpfs -o size=$USRSBINSIZE none /usr/sbin > /dev/null 2>&1
mount -t tmpfs -o size=$USRLIBSIZE none /usr/lib > /dev/null 2>&1
cd /usr/bin && tar xpf /root/usr_bin.tar > /dev/null 2>&1
cd /usr/sbin && tar xpf /root/usr_sbin.tar > /dev/null 2>&1
cd /usr/lib && tar xpf /root/usr_lib.tar > /dev/null 2>&1
eend $? "Some RAM filesystems did not mount"
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Step 5
Modify the bootloader
| Code: |
cat /boot/grub/grub.conf
################
timeout 3
default 0
# For booting GNU/Linux from an existing install (rescue)
title Gentoo
root (hd0,0)
kernel /bzImage root=/dev/ram0 rw init=linuxrc video=vesafb:ywrap,pmipal,1024x768-16@70
initrd /initrd
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Step 6
If you find that /usr/lib is too big to make a reasonable RAM drive, perhaps move some things to /usr/local/lib/ and link them, eg:
| Code: |
cd /usr/lib
for I in perl5 python2.3 portage modules gcc gcc-lib; do
mv $I ../local/lib/
ln -s ../local/lib/$I $I
done
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Putting portage in the RAM drive sure is a nice speedup, tho.
| Code: | time /usr/bin/emerge -s mozilla
real 0m3.680s
user 0m2.978s
sys 0m0.131s |
Step 7
Finalizing
| Code: | mv /usr/sbin /usr/.sbin
mv /usr/bin /usr/.bin
mv /usr/lib /usr/.lib
reboot |
###########Aside##########
If you just want to load certain applications from a RAM disk, you can do something like the following
| Code: |
##do this in advance
tar cpf /root/preload.tar /usr/bin/firefox /lib/and /lib/all /usr/lib/of /usr/lib/the /lib/raries/ it's/dependent /lib/on
##replace all the original bins and libraries with links to /preload/whatever
##Then put this in /etc/conf.d/local.start
mount -t tmpfs -o size=128m none /preload > /dev/null 2>&1
cd /preload && tar xfp /root/preload.tar |
#########################
Last edited by thebigslide on Mon Mar 14, 2005 4:32 pm; edited 25 times in total |
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BlindSpy
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Joined: 20 Mar 2004
Posts: 263
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| Posted: Fri Feb 18, 2005 9:26 pm Post subject: |
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this is probably one of the coolest things i've ever seein! I should just buy like 5 gigs of ram and have as much ram as my laptop has hdd space.
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bet1m
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Posts: 631
Location: Kosova/Prishtine
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| Posted: Fri Feb 18, 2005 10:18 pm Post subject: |
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or only /lib and /usr/lib to put in ram, Firefox will load on 0.01 sec. 
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Need4Speed
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Joined: 06 Jun 2004
Posts: 497
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| Posted: Fri Feb 18, 2005 10:38 pm Post subject: |
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| bet1m wrote: | | or only /lib and /usr/lib to put in ram, Firefox will load on 0.01 sec. |
 :drool:
I got to get more ram!!  I know a guy who bought a dual opteron system with 16gigs of ram just so he could do this. |
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thebigslide
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Location: under a car or on top of a keyboard
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| Posted: Sat Feb 19, 2005 4:57 am Post subject: |
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Rewritten following a reinstall.
This should suite anyone with between 256MB and 1GB of RAM now.
Last edited by thebigslide on Sat Feb 19, 2005 7:33 am; edited 1 time in total |
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Jinidog
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Posts: 593
Location: Berlin
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| Posted: Sat Feb 19, 2005 7:24 am Post subject: |
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Oh, how sad that /usr/lib ist as big as my RAM (1 GB).
This all brings nothing when there is something swapped.
I would rely on the caching of the kernel.
If there is RAM free, diskspace is cached, if the applications need RAM, they use it.
There is now swapping (swapping costs time).
I don't think that this will speed up anything in real life.
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Sat Feb 19, 2005 7:35 am Post subject: |
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Maybe you should clean out your /usr/lib/? Mine is only 200MB and I have TONS of apps installed.
Adended howto and provided an example of precacheing 1 app. |
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stahlsau
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Joined: 09 Jan 2004
Posts: 584
Location: WildWestwoods
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| Posted: Sat Feb 19, 2005 9:26 am Post subject: |
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nice howto, thank you!
I´ll test it anyway, but do you notice some performance-boost? I´ve tried to put some files and libs on a ramdisk before, but it wasn´t faster than it was without... |
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Sat Feb 19, 2005 11:00 am Post subject: |
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I am going to try this on a 29 node ltsp server this weekend. right now, if everyone opens firefox, it sits and chugs for minutes before everyone has it open. We'll see if this makes a difference.
For me, my HD is damn fast anyways. It just replaced it with a 200GB seagate. It is definately faster with the libs running off RAM (I only have 512MB), but it was pretty fast to begin with.
I like the idea of doing this with a CD booting OS so the damn disk doesn't have to keep spinning up and down, tho. |
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Zuti
Tux's lil' helper
Joined: 09 Jul 2003
Posts: 123
Location: The Netherlands
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| Posted: Sat Feb 19, 2005 12:35 pm Post subject: |
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thebigslide, i see you often msg-ing the tweaks posts 
Dude, you are so cool.
Tnx. |
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COiN3D
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Joined: 02 Aug 2004
Posts: 543
Location: Munich, Germany
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| Posted: Sun Feb 20, 2005 10:29 am Post subject: |
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Hey there,
nice guide, but some parts are hard to understand I think.
| Quote: | /usr must be on it's own partition
/home must be on it's own partition if it's large or you use it for storage
/root must be on it's own partition if you're putting anything big in it
/var on it's own partition (so we don't fill up the RAM drive with logs/portage cache)
an empty directory called /newroot
You must have a partition to store the tarballs on (I use the same partition that ends up being /root) and it can't be /usr.
Maybe use the partition that was / during the install
computer must have a spare 176MB of RAM or so.
(Depends how much you want to load into RAM) |
Do you mean I should create more partitions and update my /etc/fstab, or is it okay to let these on my root-partition? Do I generally have to edit my fstab file?
Sorry if some of those questions sound stupid to you, but I'm really lookin forward to try it out
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paperp
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Posts: 544
Location: Toscana , Italy
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| Posted: Sun Feb 20, 2005 2:28 pm Post subject: |
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| Just an info for a non geek ; if i move lib e usr/lib on ram , usual apps like firefox , evolution and maybe X itself take a big advantage in term of speed?? |
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float-
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Joined: 31 Aug 2003
Posts: 174
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| Posted: Sun Feb 20, 2005 4:15 pm Post subject: |
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| really sweet howto |
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Tue Feb 22, 2005 12:52 pm Post subject: |
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| paperp wrote: | | Just an info for a non geek ; if i move lib e usr/lib on ram , usual apps like firefox , evolution and maybe X itself take a big advantage in term of speed?? |
Apps open instantly, but they don't run any faster. What this does is eliminate the bottleneck of loading the applications and their dependent libraries into RAM off the HD. Also, RAM seeks WAY faster than a HD, so if multiple instances of an app are called, the system doesn't sit and chug for 10 minutes while the hard-drive tries to do 100 things at once.
I set this up on an LTSP server with 1GB of RAM and it was quite fast with 4 clients connected. I then powered up the other 30 workstations and it ran out of RAM (because they have KDE on the silly thing) and ran horribly because it was swapping. 30 KDE desktops sure use a lot of RAM (about 40MB a piece). The RAMdisk was 512MB and had /bin, /sbin, /lib, openoffice firefox, AND most of /usr/lib on it. |
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odegard
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Posts: 324
Location: Trondheim, NO
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| Posted: Tue Feb 22, 2005 5:52 pm Post subject: |
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How much work would it be to make a script that let's you pick programs already installed, create the neccessary dir's and put everything into ram upon reboot?
It should be a simple option to move programs to and from memory...
Imagine what this would do for Linux! Next time you show some friend of yours Linux, just fire up firefox/whatever and *zip* it's there. Startuptimes alone makes a huge impression.
Bravo, great work!  |
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rcxAsh
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Posts: 457
Location: /etc/localtime
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| Posted: Tue Feb 22, 2005 10:48 pm Post subject: |
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| thebigslide wrote: | Maybe you should clean out your /usr/lib/? Mine is only 200MB and I have TONS of apps installed.
Adended howto and provided an example of precacheing 1 app. |
Wow, my /usr/lib is nearly 1GB as well... how would you suggest cleaning it out without breaking anything?
This RAM stuff sounds really cool.. I just wish I had more RAM to burn. Only 256MB here. Though, perhaps I may try it out with single applications later.
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madbiker
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Joined: 12 Oct 2003
Posts: 439
Location: Victoria, BC, Canada
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| Posted: Wed Feb 23, 2005 1:38 am Post subject: |
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Mine is also nearly 1 GB. It's looking like thebigslide might be the minority instead of the norm on this one.
I'll admit I have a fair number of programs installed, but I clean out old and unused packages regularily. I need everything that I have installed right now... too bad. |
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thebigslide
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| Posted: Wed Feb 23, 2005 5:18 am Post subject: |
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Hmm, you guys are missing a big plus to this. By putting critical things on a RAM drive and umounting the partition that holds the tarballs and the update script, you are preventing changes to those files except when you run the script to do so. If someone were to h@><0r your b0><0r, they'd be changing things in a RAM drive that is flushed as soon as you reboot! This is also awesome fun for a honey pot running SSH with a typical password or a service with a well known vulnerability. You can see how people go about exploiting these boxes by simply diffing the filesystems and learn how to better secure your _real_ servers (which are also packing a root RAM drive for security).
To those of you with large /usr/libs: did you look to see what was using the space? I'm just curious. If you use rox-filer, there's a nice count feature that tells you the total folder size for multiple selected folders. You can get a nice idea of where your disk-space is going.
Also, you can easily make a folder in /usr called preload (or whatever) and mount that in a RAM drive, link things back to /usr/lib and the silly symlinks that rely on .. to point to /usr will still work  The lets you pick and choose what is loaded and what isn't loaded into RAM very eaily and could be automated with a simple bash script.
odegard:
My buddy Cory is working on one of these right now that takes the binary name as an argument and copies it and all it's dependent libraries to a tmpfs mount and links back to the original after renaming the originals .whatever. The script will soon have start and stop functions and take a config file. Might make an interesting addition to some people's init scripts.
Also, btw, I have shown this to a hard core winblowz user who swore he'd never convert to using linux on his desktop because it appears slower (even though his HTPC I made him runs KDE on gentoo on a dual AMD 1800+ box  ) He was jealous.
People like me are working towards making linux easier for the windows transition crowd. Having apps startup fast is a big thing for those people (especially if they've spent a ton of $$ on a computer already so it will have acceptable performance under windows). Other projects this particular gentooer is working on include a GUI based livecd and various lightweight stage4 tarballs that can be rebuilt with -e world transparently after install, to allow people to install a working gentoo OS with under 5 minutes of interactivity (and that in a gui) along with post-stages that will add functionality in different areas as binaries and then be easily recompiled/optimized later. All use ebuild and portage. Look out for more howtos
I love Gentoo.
Last edited by thebigslide on Wed Feb 23, 2005 5:27 am; edited 3 times in total |
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Wed Feb 23, 2005 5:22 am Post subject: |
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| failcase wrote: | Hey there,
nice guide, but some parts are hard to understand I think.
| Quote: | /usr must be on it's own partition
/home must be on it's own partition if it's large or you use it for storage
/root must be on it's own partition if you're putting anything big in it
/var on it's own partition (so we don't fill up the RAM drive with logs/portage cache)
an empty directory called /newroot
You must have a partition to store the tarballs on (I use the same partition that ends up being /root) and it can't be /usr.
Maybe use the partition that was / during the install
computer must have a spare 176MB of RAM or so.
(Depends how much you want to load into RAM) |
Do you mean I should create more partitions and update my /etc/fstab, or is it okay to let these on my root-partition? Do I generally have to edit my fstab file?
Sorry if some of those questions sound stupid to you, but I'm really lookin forward to try it out |
Sorry I missed your post earlier.
You must have any large folder on it's own physical partition on the disk.
You will have to edit fstab if you'd like the partitions mounted by gentoo automatically.
/var especially must be on it's own partition or someone can DoS your logger and maybe other things by making it fill up the RAM drive. |
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stahlsau
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Joined: 09 Jan 2004
Posts: 584
Location: WildWestwoods
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| Posted: Wed Feb 23, 2005 7:12 am Post subject: |
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nah, i´ve tried to try it, but i´ve failed with the common "kernel panic: unable to find init. Try passing init= at the kernel line".
Initrd is found, kernel boots fine, then this error. But:
-i HAVE linuxrc
-i HAVE passed the option
dunno. I remember having this probling when i built my own stage4-livedvd, and i fixed it, but i can´t remember how.
And i´ve read almost any post on this forum that´s related to this.
K, some description:
-linuxrc is on / in my initrd
-line from grub: | Code: | | kernel /bzImage root=/dev/ram0 rw init=/linuxrc ramdisk=32768 |
-i also changed the init= to every path i could think of and copied the file everywhere, no go.
Any ideas anyone? |
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Wed Feb 23, 2005 9:41 am Post subject: |
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is linuxrc executable?
What are it's contents?
You can try setting init=/bin/sh in grub and then enter your initrd line by line, also. |
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asph
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Joined: 25 Aug 2003
Posts: 741
Location: Barcelona, Spain
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| Posted: Wed Feb 23, 2005 12:34 pm Post subject: |
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great idea and howto, thanks
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gentoo sex is updatedb; locate; talk; date; cd; strip; look; touch; finger; unzip; uptime; gawk; head; emerge --oneshot condom; mount; fsck; gasp; more; yes; yes; yes; more; umount; emerge -C condom; make clean; sleep |
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stahlsau
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Joined: 09 Jan 2004
Posts: 584
Location: WildWestwoods
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| Posted: Wed Feb 23, 2005 2:02 pm Post subject: |
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hi,
@thebigslide:
linuxrc is executable, works if i start it by hand, and if i set init=/bin/bash i get a shell and can do my job.
Only if i call linuxrc it doesn´t work, even if i copy it to /bin and call init=/bin/linuxrc from grub. Dunno.
Thanks for the help, maybe s/o has another answer for me
Another one:
if i call "pivot_root . newroot" it tells me "no such device...". It only works for me if i set newroot to some available directory.
Now a tip from me:
I don´t use your tar-solution for /bin, /sbin etc. Instead i use my old root-partition which i mount in /store. Then i copy over /bin, /etc, /sbin, ... to my root-ramdrive (~50mb), unmount /store and proceed. So i don´t need to modify localmount and don´t need to untar (takes too much time for me)
for backing up my files before reboot/halt, i use this lil script:
| Code: | #!/bin/sh
cd /
mount /dev/hda3 /hdd
rsync -auv --delete /bin /etc /sbin /lib /root /hdd/
echo "Backup complete."
umount /hdd |
just put it into /etc/conf.d/local.stop. |
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thebigslide
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Joined: 23 Dec 2004
Posts: 792
Location: under a car or on top of a keyboard
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| Posted: Wed Feb 23, 2005 4:37 pm Post subject: |
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| stahlsau wrote: |
Another one:
if i call "pivot_root . newroot" it tells me "no such device...". It only works for me if i set newroot to some available directory.
[/code]
j |
you need to mkdir /newroot on your root filesystem before tarring it up /newroot is the path that the initrd will reside at following the pivotroot so it must exist for the command to be executed. |
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stahlsau
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Joined: 09 Jan 2004
Posts: 584
Location: WildWestwoods
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| Posted: Wed Feb 23, 2005 7:01 pm Post subject: |
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| Quote: | | you need to mkdir /newroot on your root filesystem before tarring it up Wink /newroot is the path that the initrd will reside at following the pivotroot so it must exist for the command to be executed. |
yeah, i noticed this
Anyway, ´til now there´s no great speed gain. Not that i would notice it, at least. I´ll try moving some of the "most-wanted" libs to the ramdisk, maybe things´ll change then. All of ´em won´t work since my /lib is 1.5G...
Any ideas what else could help speeding things up? I´ve got ~550mb ram free |
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