Okay so when we first had apps to SD, we used an extended partition called EXT2. And then cyanogen and all the other devs decided that ext2 wasn't as good as ext3. Now I realize that there's an ext4. So my question is, is there an infinite list of ext filesystems and is it a coincidence that ext2<ext3<ext4?
The question relies on a bit of history.
ext - (extended file system) which was a file system used in minix and *nix.
ext2 (second extended file system) was a replacement for ext. Primarily this allowed for larger files and longer file names.
ext3 was the replacement for ext2... intuitively enough. the most important thing it added was journaling. There were quite a few other changes but the journal is the reason ext3 is favored for the G1. The short version is that an journaled file system is less likely to become corrupt if not powered off correctly.
ext4 extends ext3. From a G1 perspective the main things it provides is some performance improvements as well as journal checksumming. There are quite a few other changes but most will not be pertinent to an embedded environment. Check wikipedia if you want a complete list.
Ext2 to ext3 is completely backwards compatible - if you make a partition ext3 you can still mount it as ext2, you just lose the journal capability while doing so.
Ext3 to ext4 is not backwards compatible if extents are used. Truthfully, unless you map extents to a smaller multiple of block size of your flash card using extents on an SDHC would probably not be advisable. People enable it with the default 128MB extent size and 4KB block size none the less. It would be a long discussion as to why this is non optimal considering a flash block size of 128KB (page size 64KB I believe) but it is not worth having.... most people enable it and so ext4 in most cases will not be backwards compatible.
EDIT: As of this moment there is not an EXT5 on the horizon. Most next gen file system work on Linux is concentrating on BTRFS and a few others whose names escape me.
EDIT2: added block size to EXT4 extents to be clearer.
JanetPanic said:
The question relies on a bit of history.
ext - (extended file system) which was a file system used in minix and *nix.
ext2 (second extended file system) was a replacement for ext. Primarily this allowed for larger files and longer file names.
ext3 was the replacement for ext2... intuitively enough. the most important thing it added was journaling. There were quite a few other changes but the journal is the reason ext3 is favored for the G1. The short version is that an journaled file system is less likely to become corrupt if not powered off correctly.
ext4 extends ext3. From a G1 perspective the main things it provides is some performance improvements as well as journal checksumming. There are quite a few other changes but most will not be pertinent to an embedded environment. Check wikipedia if you want a complete list.
Ext2 to ext3 is completely backwards compatible - if you make a partition ext3 you can still mount it as ext2, you just lose the journal capability while doing so.
Ext3 to ext4 is not backwards compatible if extents are used. Truthfully, unless you map extents to a smaller multiple of block size of your flash card using extents on an SDHC would probably not be advisable. People enable it with the default 128MB extent size and 4KB page size none the less. It would be a long discussion as to why this is non optimal considering a flash block size of 128KB (page size 64KB I believe) but it is not worth having.... most people enable it and so ext4 in most cases will not be backwards compatible.
EDIT: As of this moment there is not an EXT5 on the horizon. Most next gen file system work on Linux is concentrating on BTRFS and a few others whose names escape me.
EDIT2: added page size to EXT4 extents to be clearer.
Click to expand...
Click to collapse
oo Awesome, THanks for the response. Cleared things up. Another thing...why didn't developers start with EXT4 then?
Ext4 support wasn't built into Android - Cyanogen (I think, don't mean to step on anyone's toes) added it in. And it is still a pretty new file system type, so after patching in support, Cyanogen still had to go back and bring in some newer patches to try and fix bugs.. It's very cutting edge still. Given time, it'll be the "standard" and we'll be poking at some other new file system and wondering why everyone doesn't use it.
The original kernel for android would not have supported ext4, since it was not available at the time of the G1 release.
I am going from memory but I think the cupcake release used a 2.6.27 kernel. This would have been before ext4 support was released for general consumption, though it might have been available under experimental.
Cyanogen and most of the custom ROMS out there are using a 2.6.29 kernel now, which has a general release of ext4. There are some known problems with the stock ext4 release in 29 but Cyanogen backported the fixes from 2.6.30. Since I believe most of the ROMS are "Cyanogized" you should be fine now with any of the current ROMS on a 29 kernel that supports ext4, which is not necessarily all of them. I pretty much stick to Cyanogen's ROMs so I can not say what the others do and do not have.
Saiboogu said:
Ext4 support wasn't built into Android - Cyanogen (I think, don't mean to step on anyone's toes) added it in. And it is still a pretty new file system type, so after patching in support, Cyanogen still had to go back and bring in some newer patches to try and fix bugs.. It's very cutting edge still. Given time, it'll be the "standard" and we'll be poking at some other new file system and wondering why everyone doesn't use it.
Click to expand...
Click to collapse
JanetPanic said:
The original kernel for android would not have supported ext4, since it was not available at the time of the G1 release.
I am going from memory but I think the cupcake release used a 2.6.27 kernel. This would have been before ext4 support was released for general consumption, though it might have been available under experimental.
Cyanogen and most of the custom ROMS out there are using a 2.6.29 kernel now, which has a general release of ext4. There are some known problems with the stock ext4 release in 29 but Cyanogen backported the fixes from 2.6.30. Since I believe most of the ROMS are "Cyanogized" you should be fine now with any of the current ROMS on a 29 kernel that supports ext4, which is not necessarily all of them. I pretty much stick to Cyanogen's ROMs so I can not say what the others do and do not have.
Click to expand...
Click to collapse
Ah Thank-you both of you. Cleared things up alot
This explains it nicely! Ext4 for cyan. Is it still a good idea to run the linux swap partition as well with ext4 and Cyan roms?
yes
you still want to run a linux-swap partion, swap and ext are 2 different things. Swap is where your system extends it's operating memory not storage as to say even a full computer linux distro uses a swap partion<I know my ububtu does> so yes if you want the benefits of swap than you better have a partion for it
Awesome..
Thanks to alritewhadeva for rising this question and thanks much to Saiboogu and JanetPanic for letting us win users what exactly these are for. Couldn't find better explanation even after googling about them.
gridlock32404 said:
you still want to run a linux-swap partion, swap and ext are 2 different things. Swap is where your system extends it's operating memory not storage as to say even a full computer linux distro uses a swap partion<I know my ububtu does> so yes if you want the benefits of swap than you better have a partion for it
Click to expand...
Click to collapse
Regarding this linux-swap.... I do have 32MB partition for that one created before installing the ROM. Now, are cyanogen's roms take advantage of this partition automatically or do I need to "enable" or change setting for that to happen?
If you read the first post on cyan's rom, I believe it does but as compcache, which I believe and I might not be right but I think it is just a better way of swap, I think more efficent
I repartitioned today to ext4. I used cyan's userint.sh and Mike Taylors user.conf. I'm not convinced it is working right at it seems more sluggish at times.
I just use a 96mb linux swap myself that I turn on with swapper and it is quite snappy, there was a thread were people were saying that comp wasn't as good as swap so I decided doing all that was just a hassle so I stuck with tried and true swap
This is the MT user.conf and the one I'm running.
# User.conf by miketaylor00
# General parameters
general{
apps2sd=0 # this is useless here, require a modified a2sd script
media2sd=1 # moves the medias to sd if /system/sd/media exists
}
#compcache related parameters
compcache{
compcache_en=1 # enable(1) or disable(0) compcache
cc_disksize=32 # Ram swap disksize - any number between 1 to 95 should work
cc_memlimit=18 # Limite the memory usage when backing swap is used
cc_backingswap_en=1 # enable or disable backing swap
cc_backingswap=/dev/block/mmcblk0p3 # pointing to the backingswap partition device
cc_swappiness=28 # default 60
}
#Linux swap parameters
#
# linux swap can only be enabled if cc_backingswap_en is set to "0"
#
linux_swap{
linux_swap_en=0 # enable(1) or disable(0) linux swap
linux_swap_partition=/dev/block/mmcblk0p3 # swap partition device
swappiness=30 # default 60
}
#virtual memory
sys_vm{
sys_vm_en=1 #enable(1) or disable(0) virtual memory configurations
page_cluster=3 # default 0
laptop_mode=0 # default 0
dirty_expire_centisecs=3000 # default 3000
dirty_writeback_centisecs=500 # default 500
dirty_background_ratio=5 # default 5
dirty_ratio=10 # default 10
}
#cpu clock
proc_cpu{
proc_cpu_en=1 #enable(1) or disable(0) user cpu configurations
# freqency options
# 19200
# 122880
# 128000
# 245760
# 384000
# 528000
scaling_min_freq=192000 # default 245760
scaling_max_freq=528000 # default 528000
sampling_rate=2000000 #default 200000 depending on kernel version
powersave_bias=0 # default 0, CM3.9.6 default uses 200
up_threshold=45 # default 40, percent cpu usage before going up a speed step
}
gridlock32404 said:
If you read the first post on cyan's rom, I believe it does but as compcache, which I believe and I might not be right but I think it is just a better way of swap, I think more efficent
Click to expand...
Click to collapse
Compcache is different to swap.
Swap is a virtual extension of the RAM, which is why it gives us a performance increase. Although adding x amount of swap space isn't the same as adding x amount of RAM.
Compcache compresses what's in RAM, which in theory increases the amount of RAM
Compressing pages and keeping them in RAM virtually increases its capacity. This allows more applications to fit in given amount of memory.
Click to expand...
Click to collapse
I flashed to Cyan's lastest this morning. I assume that user.conf and userint.sh was replaced with Cyans own?
I'm super fuzzy on all this, as I will be running Cyan's roms from now on, I just need a system/setup/ext that's optimized for his roms. I didn't have much luck with MT's for whatever reason. It ran, just lagged.
Related
Hey guys can you suggest me the perfect settings for my 2GB sd?
Do I need to use Swap? (now I have 64 mb of swap)
What kind of EXT it's best? (now I have ext4)
Thank you!
Krishath said:
Hey guys can you suggest me the perfect settings for my 2GB sd?
Do I need to use Swap? (now I have 64 mb of swap)
What kind of EXT it's best? (now I have ext4)
Thank you!
Click to expand...
Click to collapse
I believe ext4 is best, as it's the newest linux filesystem. I'm currently using ext3, because most ROMs don't support ext4, but I'll probably upgrade soon.
As for swap, I also have a 64mb swap partition, but default it isn't utilized. CompCache is already enabled, but I'd also like to know how to enable it.
EDIT: Swap requires a userinit.sh I'm about to try it out...
AdrianK said:
I believe ext4 is best, as it's the newest linux filesystem. I'm currently using ext3, because most ROMs don't support ext4, but I'll probably upgrade soon.
As for swap, I also have a 64mb swap partition, but default it isn't utilized. CompCache is already enabled, but I'd also like to know how to enable it.
EDIT: Swap requires a userinit.sh I'm about to try it out...
Click to expand...
Click to collapse
Yeah but what it's the best setting for this ROM?
EXT4 + SWAP 64MB are alright?
So swap partition isn't used by default? How we "activate" it?
Krishath said:
Yeah but what it's the best setting for this ROM?
EXT4 + SWAP 64MB are alright?
So swap partition isn't used by default? How we "activate" it?
Click to expand...
Click to collapse
Isn't much difference between ext3 and ext4. Cyanogen himself uses ext4, so...
You need to make a custom userinit.sh, follow that guide I posted.
Swap size probably doesn't matter too much, as long as it's not too big. 64 will be fine, any speed increase from a different size will be minimal.
This is how I'm running 4.0.4...
- 32MB Linux Partition - enabled using Swapper.
- 528MHz set ALL the time - enabled using SetCPU(Makes the UI sooo much smoother. Didnt really notice a difference in battery life either).
Using userinit.sh I enabled CompCache with linux swap on a 64 partition and it does seem smoother. Also switched to ext4 now, don't really see a difference.
Will try it now
AdrianK said:
Using userinit.sh I enabled CompCache with linux swap on a 64 partition and it does seem smoother. Also switched to ext4 now, don't really see a difference.
Click to expand...
Click to collapse
Can you post your usernit.sh?
AdrianK said:
Using userinit.sh I enabled CompCache with linux swap on a 64 partition and it does seem smoother. Also switched to ext4 now, don't really see a difference.
Click to expand...
Click to collapse
i would suggest you stick to ext3 because it's more commonly used as of right now... also 64mb is a good sized partition, and linux swap is good, but compcache and Backing Swap is a lot better...
prince.siraj said:
i would suggest you stick to ext3 because it's more commonly used as of right now... also 64mb is a good sized partition, and linux swap is good, but compcache and Backing Swap is a lot better...
Click to expand...
Click to collapse
Can I have some "made" files to put in my SD card? I have a "normal" 2GB microsd card with 64 mb of swap... I'd be glad for this
I really dont see anything wrong with ext4, Ive had a look in a few rom release threads and most of them have support for it. I use cyanogen mod 99% of the time anyway...
Krishath said:
Can I have some "made" files to put in my SD card? I have a
"normal" 2GB microsd card with 64 mb of swap... I'd be glad for this
Click to expand...
Click to collapse
Are you talking about userinit.sh and user.conf? Just follow the link I posted earlier, took me about 10 minutes to set up.
for swap dont go over 45mb. i honestly can notice the dif. i us my g1 as a test dummy. ext2,3,4 honestly does not make a dif in my eyes. i have tried all. i use linux mint to partition my sd. which by the way is the easiest and sickest way to partition. just had to put that out there for lin users. root root lol!! but ya. over 45mb makes me feel its really trying to find the swap space. try it and give me your opinion. i have partitioned my sd from recovery mkpartfs, windows partition to linux partition editor. ya. trust me. i currently use 40mb swap. that is what really matters. use at ur comfort and day to day usage. fosho!!
Hello!
I have a G1 using CM 4.1.999, and my microSD is partitioned with an ext4 for apps2sd and a 64MB linux-swap partition.
I am using the user-configurable userinit.sh with user.conf.
I am trying to understand the cc_disksize and cc_memlimit settings.
My understanding is that it used to be that no matter how I set these I will get a compcache of 15% of total RAM with a backing swap using the entire linux_swap partition.
But I am a bit confused as this rom has compcache 0.6, and I am not sure if that limitation still applies after .5x.
If that is the case, I want to confirm... if I set cc_disksize to 0 and set cc_memlimit to 32, I will get a RAM compcache of 32MB, and it will use the entire linux_swap partition as backing swap.
Is this correct?
Thanks for any help you can give me in understanding this!
Sorry for the bump, but I'm hoping a little more clarification might be a little more answerable...
Well i cant give you a definitive answer, but i can point you in the right direction.
If you don't get much help here, you can try PM'ing miketaylor00
he spent considerable amount of time talking about the subject and his user.conf is implemented in JACxROM
you can send him a link to this q&a and maybe he'll help you out. im sure a lot of people would like more clarification
i also believe the defaulting to 15% of ram was fixed in 0.6 compcache
i havent messed with these settings much. i messed around with them when they first came out but stopped after 0.6 and just started using whatever was included default in the rom. swappiness was pretty much the only settings i changed
bradycl_84043 said:
Hello!
I have a G1 using CM 4.1.999, and my microSD is partitioned with an ext4 for apps2sd and a 64MB linux-swap partition.
I am using the user-configurable userinit.sh with user.conf.
I am trying to understand the cc_disksize and cc_memlimit settings.
My understanding is that it used to be that no matter how I set these I will get a compcache of 15% of total RAM with a backing swap using the entire linux_swap partition.
But I am a bit confused as this rom has compcache 0.6, and I am not sure if that limitation still applies after .5x.
If that is the case, I want to confirm... if I set cc_disksize to 0 and set cc_memlimit to 32, I will get a RAM compcache of 32MB, and it will use the entire linux_swap partition as backing swap.
Is this correct?
Thanks for any help you can give me in understanding this!
Click to expand...
Click to collapse
Yes, your assumptions are correct. If you have backing swap enabled it will use the entire swap partition. You can check the stats with this command:
Code:
su
rzscontrol /dev/block/ramzswap0 -s
The disksize value when you have backing swap enabled should always equal the size of the swap partition. I recommend a 32MB swap partition if you are using a ROM that doesn't have BFS and a 64MB swap if it does have BFS.
The memlimit is the amount of uncompressed data that can be used by compcache. It usually compresses down to about 20-25% of the uncompressed size so with a 32MB setting it will only use about 5-8MB of RAM. I've been using a 32-48MB memlimit lately and it works great. If you are on a BFS ROM I would go with 48MB. I believe that CM is using BFS I just wanted to give the info for both in case someone else reads this down the road. There is a lot of info about the stats on this page.
http://code.google.com/p/compcache/wiki/StatsExplained
If you have any more questions shoot me another PM. I hope this helped.
Hey guys,
Sorry to ask, and forgive me for been dumb, not really a Linux user here.
I need help with some details. I have my Hero - rooted with 0.7 Fresh 8GB SD on it.
What is the advantages of partitioning your SD - let's assume :
Swap-size = from 32mb to ummm 1024MB
Ext2-size = from 512mb to ummm another 1024mb.
Is there any standard procedure/requirement for this.
Also, let's assume I did this and this the following :
SD: ext2 to ext3
Can anyone put this in English language for me
I did all of this and was hoping that my phone would reflect a different internal memory size, but it still shows what I had before. I also noticed under "computer management that my SD got reduced by the amount I specified earlier from HTC Recovery mode.
Many thanks in advance
There are 2 different methods for setting up Apps2SD the most common method does not show any reflection in your About Phone screen. The other UNIOn method does, but i have seen very few people use this and I have not clue how to do it. No big deal either way you do it.
If you load the newest recovery from AMON_RA you can specify the size of your partitions. It seems like you are probably using this.
If you ever fill up a 1 gig swap someone wrote a very badly handled program in terms of memory. Swap = Linux version of the Windows Page file. The more you have doesn't necesarily mean the phone will move faster, it just means you have more room to grow. you are still using RAM for programs currently in USE. Swap just holds the stuff out of RAM until it is needed.
ext2 to ext 3: Ext3 from what I understand is just adds journaling and does its own repairs/checks. Stops you from waiting around while ext2 fixes itself if something bad happens.
I am sure someone can correct me if I am wrong on any of this.
I found tutorial how to use ext2 partition on SDCARD for haret.
http://android-devs.org/forum/viewtopic.php?f=56&t=194
I created this
2 GB Fat32
1 GB ext2
1 GB ext2
so i have 4 GB disk and 3 partition just as its on tutorial
But after launching haret it should asked me
Press VolDn to launch Installer (to use ext2)
just after the
Checking for partitions
but in my case it just continue with installing without asking me and its uning only fat32
Any suggestion???
our rootfs doesn't have the install function, someone must edit the rootfs to boot into EXT partitions first!
I just copy rootfs to the / of the ext2 and system to /system, and then edit the init script so it remounts properly.
When I start doing partitioned releases I'll try and make it easy, probably by distributing prebuilt images by card size (4G, 8G etc.)
Tremere said:
When I start doing partitioned releases I'll try and make it easy, probably by distributing prebuilt images by card size (4G, 8G etc.)
Click to expand...
Click to collapse
I talked to phh yesterday.. he said ext2 and NAND booting have no effect on stability, performance and battery life. (rhod nand booting has been working for one month)
Performance could change but it would be less than 20%.
So I pray that someone will find the standby killer
So i need only one ext2 partition
Tremere said:
and then edit the init script so it remounts properly.
Click to expand...
Click to collapse
if i knew how and what to edit. Nevermind its not that important. You just focus on your work.
Matzemink said:
I talked to phh yesterday.. he said ext2 and NAND booting have no effect on stability, performance and battery life. (rhod nand booting has been working for one month)
Performance could change but it would be less than 20%.
So I pray that someone will find the standby killer
Click to expand...
Click to collapse
True. I think they also had an incorrect mount option on the rootfs until recently that slowed loopback performance. I think my last (unstable) release contained the fix for that.
For my own AOSP device tree I'm determined to start fresh without the rootfs and loopback crap. Maybe not a big performance gain but easier to 'get around' system wise.
if i knew how and what to edit. Nevermind its not that important. You just focus on your work.
Click to expand...
Click to collapse
off the top of my head, init.etc/init.froyo.rc and there is a line which tries to mount root as yaffs (flash). Not too hard to find.
You might want to have another ext2 for /data though.
How do I partition my micro sd card?
please excuse my bad English
I use translator
The easyest way for me. Download a release of Ubuntu from ubuntu.com and burn it to cd or make bootable USB. Boot live cd and partition from there.
wouldn't it be easier to download a live CD of gparted?
Jonny4911 said:
wouldn't it be easier to download a live CD of gparted?
Click to expand...
Click to collapse
System Rescue CD is my favorite for partitioning tasks. Should work on your sdcard.
Over in the raph forum, e334 posted a guide on partitioning ext2 from Windows
[DEV-HINT] Implementing a swap partition or swap file for new and old bootloader
Wikipedia defines swap file (or paging) as: "[..] use disk storage for data that does not fit into physical random-access memory (RAM)."
With CM10 or CM10.1 around, the 'about phone' screen usually shows 343 MB of usable RAM on the LG-P990, so one gets ideas. With CM9 it was a bit better, but still.... Take Chrome for example: nice to the eye, but not so nice to the RAM of devices that have been around a lot longer than the Nexus 4 with its whopping two Gigabytes. So what's the catch with swap? For example, a HDD swap partition on a PC offers some sort of relief when RAM is scarce by moving some parts of the RAM (pages) to the HDD and moving them back when it needs it. Of course, it comes for a price: performance! But it works. So why not using it on Android too? To hell with the fact that virtual RAM on the internal memory card is a lot slower than physical RAM, there are times when it would be just nice to have the extra megabytes at hand.
Were you a bit envious too when you saw that the 'new' partition layout that came with the ICS bootloader on our beloved LG-P990 had a swap partition included? Well, I was. I even changed to a customized layout to get one for a little while too... But that is not really necessary. Never was, actually. I came back to the original layout and old bootloader weeks ago. What still bugged me was the missing swap partition. CM10.1, CM10 or even CM9 could really use swap from time to time but commonly don't use it.
So, is there really a big difference between the two partition layouts? Yes, but regarding the swap it doesn't count. In fact, the situation for both user groups is pretty much the same: both do not use any kind of swap space whatsoever. First, there are the users with the new bootloader. They have the swap partition but actually don't make use of it. As compared with users with the old bootloader: they may not have the swap partition on their partition table but even they can easily implement a solution very similar to a standard swap partition: a swap file. Then they can benefit as well from some extra Megabytes in certain low memory situations. You don't have a swap partition/file in use yourself yet? In just a few minutes you can change that no matter what bootloader you have.
First you have to find out which bootloader/partition layout is on your LG-P990:
here is how you determine your bootloader/partition layout: reboot!
If you see a pink LG logo when the phone boots then you have the new bootloader/new partition layout (ICS)
If you see a white LG logo when the phone boots then you have the old bootloader / old partition layout(GB)
All commands used in the terminal are shown with a '$'-sign or '#'-sign (root). Copy just the commands without the signs to the terminal, unless stated otherwise.
New bootloader/partition layout (ICS) - Pink LG logo as splash screen - You have the old bootloader/partition layout? Skip to the second part below.
If you are using the new partition layout, then it is easy to use the swap mechanism. The 350MB swap partition is just waiting for you to be switched on.
Use 'adb shell' or the terminal:
check the situation with
Code:
$ free
Does it show 0 0 0 in the swap line? Then swap is not working at the moment and has to be switched on.
Use
Code:
$ su
to get superuser rights
Make the swap partition usable (Be extra careful! Triple-check the command!)
Code:
# mkswap /dev/block/mmcblk0p4
Switch it on
Code:
# swapon /dev/block/mmcblk0p4
Change swappiness to zero at runtime
Code:
# sysctl -w vm.swappiness=0
To keep the swap partition switched on, after reboot and even after flashing ROM updates
create the file /data/local/userinit.sh
Put these lines inside (with the '#' sign)
Code:
#!/system/bin/sh
swapon /dev/block/mmcblk0p4
sysctl -w vm.swappiness=0
swappiness=0 lets the kernel use the swap partition only when there is no more physical RAM left.
Save the file.
Now reboot.
Check it via adb shell or terminal if it is working.
Code:
$ free
The swap line should show that 350 MB are available (total/free).
Check the swappiness with
Code:
$ cat /proc/sys/vm/swappiness
It should show 0 now.
Testdrive your work. Start Chrome or a game or whatever uses a lot of RAM on your system. Use it heavily and then check the swap usage of your kernel again with a final
Code:
$ free
Just try it!
Old bootloader/partition layout (GB) - White LG logo as splash-screen
The task is to create a 128 MB Swap-File on the data partition. 128 MB seems enough since it is just for memory emergencies. And it's best to create it on the data partition and not on the sdcard because of the USB mass-storage support that would interfere with any swap file on sdcards. By the way, it doesn't format your data partition. It just makes your usable space of the data partition 128 MB smaller than it is right now. Basically, it creates an empty file with the fixed size of 128 MB and makes it usable as a swap 'partition'. It has the same functionality as a swap partition. And the same speed. And everything else. It just doesn't reside in its own partition. It is even better: when you don't want it anymore or change the size of it, just stop the swap-file with 'swapoff' and delete the file 'swapfile' in your data partition and it's gone for good. Immediately you can use the freed-up space for something else.
Use 'adb shell' or the terminal:
check the situation with
Code:
$ free
Does it show 0 0 0 in the swap line? Then it is not working at the moment and has to be switched on.
See with
Code:
$ df
whether there is enough free space left on /data. 200 MB or more should be free on /data. 128 MB will be used.
Get superuser rights
Code:
$ su
Optional: To see more interesting memory stats you can use
Code:
# cat /proc/meminfo
Now create the file named 'swapfile' with the size of 128 MB
Code:
# dd if=/dev/zero of=/data/swapfile bs=1024 count=128000
This can take a moment.
Limit the rights of the swapfile
Code:
# chmod 600 /data/swapfile
now set up the swapfile for swap usage
Code:
# mkswap /data/swapfile
Switch it on
Code:
# swapon /data/swapfile
Hint: switch off would be swapoff /data/swapfile
Now it is already working!
Tune it to your needs: we just want the swap file to be used in emergencies when there is no RAM left anymore and Android would turn Project Butter in Project Stutter.
Check the status of swappiness
Code:
# cat /proc/sys/vm/swappiness
Default is 60. That is much too high. swappiness=0 lets the kernel use the swap file only when there is no more physical RAM left.
Change it to zero
Code:
# sysctl -w vm.swappiness=0
With this sysctl command you can change the swappiness setting (0-100) on runtime.
If you want to make these settings permanent no matter if you reboot or even flash a ROM update without wiping data then
create the file /data/local/userinit.sh
Put these lines inside (with the '#' sign)
Code:
#!/system/bin/sh
swapon /data/swapfile
sysctl -w vm.swappiness=0
Save it.
Reboot and check it with a last
Code:
# free
in terminal. Now testdrive your swap file with two browsers and a game simultanously or whatever suits your needs to stress your P990.
Just try it yourself!
Have fun!
and another awesome dev thread by Raum1807 :good:
Interested in making a flashable zip out of it? If not I could do it next week.
Just adding everything into one sh-file which gets called by the updater-script - or just via the Terminal.
tonyp said:
and another awesome dev thread by Raum1807 :good:
Interested in making a flashable zip out of it? If not I could do it next week.
Just adding everything into one sh-file which gets called by the updater-script - or just via the Terminal.
Click to expand...
Click to collapse
Thanks for the offer. Thought about that, too. But I think it is more interesting to understand what we are doing here by following it step-by-step. A script makes it too easy... Maybe later, we will see.
sorry for this dumb question.
what's the difference between using this method and using roehsoft ram expander?
both of them have the option to change swappiness and to enable/disable swap from sdcard (roehsoft ram expander can even choose ext sd as swap location)
i don't get it :silly:
old bootloader:
/data/swapfile # that's internal sd right?
wouldn't it be better to use external sd for swapping as swapping heavily might in the long run kill a flash drive?
derEremit said:
old bootloader:
/data/swapfile # that's internal sd right?
wouldn't it be better to use external sd for swapping as swapping heavily might in the long run kill a flash drive?
Click to expand...
Click to collapse
i don't think so, AFAIK the max reading speed for ext sd is 10 MBps, which is lower than reading speed in our int sd (about 13 MBps). that's why using int one for swapping would be a better choice
please CMIIW, i'm still noobs in this kind of stuff. though, i just want to share what i know
I have one point to this.
You write "swappiness=0 lets the kernel use the swap partition only when there is no more physical RAM left."
But there is every time some free space on RAM, because android never let decrease memory to zero.
babi_perang said:
sorry for this dumb question.
what's the difference between using this method and using roehsoft ram expander?
both of them have the option to change swappiness and to enable/disable swap from sdcard (roehsoft ram expander can even choose ext sd as swap location)
i don't get it :silly:
Click to expand...
Click to collapse
- Doesn't use the external sdcard
- Doesn't cost 7 Euro
- gives you an idea how things work
Sent from my LG-P990 using xda app-developers app
derEremit said:
old bootloader:
/data/swapfile # that's internal sd right?
wouldn't it be better to use external sd for swapping as swapping heavily might in the long run kill a flash drive?
Click to expand...
Click to collapse
Swapping is only happening when the RAM is critically low. Btw, the swap partition of the ICS partition layout is also located on the internal memory. No difference so to speak. Using this method shouldn't harm the internal memory at all.
Sent from my LG-P990 using xda app-developers app
tomsi91 said:
I have one point to this.
You write "swappiness=0 lets the kernel use the swap partition only when there is no more physical RAM left."
But there is every time some free space on RAM, because android never let decrease memory to zero.
Click to expand...
Click to collapse
Yes, the memory management of Android tries to keep the RAM clean while keeping the last few opened apps in the RAM. Four or five running CM10.x on the P990. But the less RAM you have on your phone the harder this balance gets. Imagine memory eating apps like Gallery/Camera or Chrome. They benefit from more memory being available.
Sent from my LG-P990 using xda app-developers app
Thank you for this helpful guide! It is so easy to make it. And now I know a bit much more about Android and RAM.
Gesendet von meinem LGP990 mit CM10.
Hey! This seems interesting but i have a question , before doing this we have 343 RAM available and after all this trouble only 350 ? so thats 7more RAM or am i missing something ?
Soare23 said:
Hey! This seems interesting but i have a question , before doing this we have 343 RAM available and after all this trouble only 350 ? so thats 7more RAM or am i missing something ?
Click to expand...
Click to collapse
Yes, you forgot to read the original post that explains what exactly swap is:
So what's the catch with swap? For example, a HDD swap partition on a PC offers some sort of relief when RAM is scarce by moving some parts of the RAM (pages) to the HDD and moving them back when it needs it. Of course, it comes for a price: performance! But it works. So why not using it on Android too? To hell with the fact that virtual RAM on the internal memory card is a lot slower than physical RAM, there are times when it would be just nice to have the extra megabytes at hand.
Click to expand...
Click to collapse
The reported RAM will remail the same because you aren't increasing your physical RAM.
When i try to creat a swap file, this Error appears:
/def/zero/: canot open for read: Not directory
I'm a superuser
---------- Post added at 09:20 PM ---------- Previous post was at 09:13 PM ----------
After disconnecting from computer it worked!
Swappiness=0 doesn't stick for me after reboot It returns to 60 everytime.
@Raum1807
Awesome thread. Thanks for kindly explaining everything. I learned a lot here!
Ajsh said:
Swappiness=0 doesn't stick for me after reboot It returns to 60 everytime.
Click to expand...
Click to collapse
just put:
echo "0" > /proc/sys/vm/swappiness
at the end of a .sh file in init.d
As we´re talking about using the wasted Swap-Partition:
Is it possible to use it as a "new" kind of Ramhack?
As for now we cut off some shared Ram of GPU to use it as normal RAM. What if we let the GPU use the Swap-Partition as its Memory and get all physical RAM available?
GPU will not perform as good as now, but some People don´t need a Phone to play Games...
Is this possible or restricted to some Nvidia-Libs that are Closed-Source??
zerocoolriddler said:
As we´re talking about using the wasted Swap-Partition:
Is it possible to use it as a "new" kind of Ramhack?
As for now we cut off some shared Ram of GPU to use it as normal RAM. What if we let the GPU use the Swap-Partition as its Memory and get all physical RAM available?
GPU will not perform as good as now, but some People don´t need a Phone to play Games...
Is this possible or restricted to some Nvidia-Libs that are Closed-Source??
Click to expand...
Click to collapse
This is interesting... it could really make a difference , only if it works tho heh.
Sent from my LG-P990 using xda app-developers app
Can we have both Swap and Zram on in CM 10 ? Any possible side effects