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[DEV] /cache converted to swap

So as we all know /cache is used for OTA updates which, when you have your phone rooted is useless.
What I'm wondering is why we can't use /dev/block/mtdblock4 (aka /cache) as a permanent onboard swap partition. Granted it will only give us an additional 30MB but the speed of this swap will be higher than that of our sdcard.
In order to test this we'll have to:
convert this partition to a linux-swap partition.
mkswap /dev/block/mtdblock4
update init.rc to no longer mount this as yaffs2
add this new swap space to the swap script
The issue is of course being able to run a partition utility on the phone. Second, if this doesn't work we don't have a way to format /cache back to yaffs2 (that I know of).
If you have experience with any of the issues I listed above please comment/post. If you don't have a clue please don't post so we can keep this thread clean. I would appreciate only experienced devs responding.
If this is possible it would benefit Hero/MotoBlur ROMS which are memory intensive.

For your second concern, why would we need to change it back to /cache? Just make it a disclaimer when people attempt this operation.
More importantly, I think the primary issue is that this is rom space is it not? Doesn't this portion of the memory have a limited amount of times that it could be written to?

Hmm why not trying "parted /dev/block/mtdblock4" in recovery? ;-)
rest would be easy.

Couldn't we use mkyaffs2img (in recovery /sbin) to turn it back into yaffs?

persiansown said:
For your second concern, why would we need to change it back to /cache? Just make it a disclaimer when people attempt this operation.
More importantly, I think the primary issue is that this is rom space is it not? Doesn't this portion of the memory have a limited amount of times that it could be written to?
Click to expand...
Click to collapse
Well my concern was if there was some adverse effect of removing /cache from the system we'd need a way to revert back.
I am not aware of any MAX amount of times that /cache can be written to.
*Edited*
Due to unintelligent comments and moronism prevalent in this thread, I removed a line from this post to keep us on track of what this thread was meant to discuss.

There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..

dumfuq said:
Couldn't we use mkyaffs2img (in recovery /sbin) to turn it back into yaffs?
Click to expand...
Click to collapse
I hadn't checked in the recovery img for any yaffs2 utilities. But if that indeed does exist then this will be possible.
So then the issue would be, is this safe to attempt long term with the amount of writes being done to internal flash?

maxisma said:
There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..
Click to expand...
Click to collapse
So I see recovery is using it but the only thing in it is the recovery logfile. Could we modify the recovery to read/write the logfile to system/sd/recovery or something, or is the cache used for other stuff as well?

Another idea:
Instead of using it as swap, what if we could find a way to use it as compcache space? That way we don't sacrifice any of the internal ram for compcache and still have compcache running

maxisma said:
There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..
Click to expand...
Click to collapse
What part of recovery needs /cache ? Does the recovery img mount the /cache partition? I'm wondering if the recovery img could be modified to write to the ext2 partition such as /system/sd/cache .

persiansown said:
Another idea:
Instead of using it as swap, what if we could find a way to use it as compcache space? That way we don't sacrifice any of the internal ram for compcache and still have compcache running
Click to expand...
Click to collapse
This is actually a good idea and it'd be interesting to see which way would benefit us more.

shafty023 said:
What part of recovery needs /cache ? Does the recovery img mount the /cache partition? I'm wondering if the recovery img could be modified to write to the ext2 partition such as /system/sd/cache .
Click to expand...
Click to collapse
When you activate an option in recovery, for example install update.zip, it writes the command into /cache/recovery and does a "quick reboot", which reads out the command and does this.

ok first dont even try it would one
reduce life on nand
cause issues with flashing
slow down any thing accessing the nand.
to the person thinking the ram is using flash. you must have never been to high school cause even typing class explains what ram is. plus g1 has memory write speeds of about 120mb/sec thats sdram. swap will never replace ram 120mb/sec versus 6 is huge

if you want real improvements you must change the code to something more efficient.
less bloat
more native code
fewer clock cycles
improved app states(cache on sd that would save the state by dumping part of ram to load later reducing clock cycles and reducing ram)
and my favorite rewrite system libs and apps to include more native code and reducing ram usage.
btw native code is about 10-100x faster than android java. that means 10%-100% more speed(or less load)

you could make a swap file and put it on there and just mount the file...........

yeah what he said!
zenulator said:
you could make a swap file and put it on there and just mount the file...........
Click to expand...
Click to collapse
This sounds like a good idea, altho we would have to get compcache working with backing swap file.
do we know if the /cache speed is compaired to Class 6 microSD?

good luck hardheads

jokersax11 said:
ok first dont even try it would one
reduce life on nand
cause issues with flashing
slow down any thing accessing the nand.
to the person thinking the ram is using flash. you must have never been to high school cause even typing class explains what ram is. plus g1 has memory write speeds of about 120mb/sec thats sdram. swap will never replace ram 120mb/sec versus 6 is huge
Click to expand...
Click to collapse
Dude honestly get a life. I have a Bachelor's degree in Computer Science. And I could code in Intel Assembly accessing each and every register in memory while you're left googling what Intel Assembly code means. Maybe you should keep up with the latest technology. If you did you'd know there are all-in-one memory chips that support NOR, NAND flash, and RAM.
http://www.eetasia.com/ART_8800466798_499486_NT_ab9e537f.HTM

jokersax11 said:
if you want real improvements you must change the code to something more efficient.
less bloat
more native code
fewer clock cycles
improved app states(cache on sd that would save the state by dumping part of ram to load later reducing clock cycles and reducing ram)
and my favorite rewrite system libs and apps to include more native code and reducing ram usage.
btw native code is about 10-100x faster than android java. that means 10%-100% more speed(or less load)
Click to expand...
Click to collapse
Exactly what type of "native code" are you referring to? And do you have any idea what type of memory the G1 uses for RAM? Go back to your typing class.

Shafty did you see Zenulator's idea? That seems like it could work.. Does the phone ever format the cache partition?

CWM Ext3/4 support - Explanation please

Can someone please, in layman's terms, explain what ext3/4 is? Also, in what scenarios is the CWM with ext4 support needed?
ThADVANCEks

Ext3/4 are different file systems... Our phone is "native" ext3... Ext4 is a little better...(faster/easier to work with?) Im not totaly sure... I know there filing systems but not much difference in performance
But the new nvflash ext4 is so we can make backups with the ext4 kernels that are out (possibly new roms)
Sent from my LG-P999 using XDA Premium App

nate420 said:
Ext3/4 are different file systems... Our phone is "native" ext3... Ext4 is a little better...(faster/easier to work with?) Im not totaly sure... I know there filing systems but not much difference in performance
But the new nvflash ext4 is so we can make backups with the ext4 kernels that are out (possibly new roms)
Sent from my LG-P999 using XDA Premium App
Click to expand...
Click to collapse
Ahhh, makes sense now. I'm glad I didn't flash an ext4 kernel/rom and get it setup the way I want it and try a backup. that would have sucked. awesome, thanks again.

Yeah I believe EXT4 is faster at read/write operations which should provide better performance for our little blazing beasts, and is also the latest of the EXT file system type. Newer is always better, right?

[Q] What are the benefits of formating the sd to ext/swap etc?

I'm a Linux user so I know what swap, ext2, ext3 etc technically means. What I don't understand is what are the *actual* benefits of formating my SD Card to these formats. I've run into a lot of guides and how-tos but no one cares to explain why to do it.
So to sum up:
Does the Android System actually cares if I create these formats?
If it does, will I notice actual increase in performance?
What about apps2SD?
What kind of format do you recomend?
I have an HTC Desire and I'm using CyanogenMod, Oxygen and MIUI in rotation (means I replace one with another every couple months).
Thanks in advance!

aventinus said:
I'm a Linux user so I know what swap, ext2, ext3 etc technically means. What I don't understand is what are the *actual* benefits of formating my SD Card to these formats. I've run into a lot of guides and how-tos but no one cares to explain why to do it.
So to sum up:
Does the Android System actually cares if I create these formats?
If it does, will I notice actual increase in performance?
What about apps2SD?
What kind of format do you recomend?
I have an HTC Desire and I'm using CyanogenMod, Oxygen and MIUI in rotation (means I replace one with another every couple months).
Thanks in advance!
Click to expand...
Click to collapse
Faster SD Card speeds for app2sd, thats mainly it. If you don't use A2SD there isnt much point to it, but if you do it can be very useful. What some people do though are format their System and Data partitions to EXT2 or EXT4 so then the whole system is faster all around and is a large improvement over stock rfs.

fowenati said:
Faster SD Card speeds for app2sd, thats mainly it. If you don't use A2SD there isnt much point to it, but if you do it can be very useful. What some people do though are format their System and Data partitions to EXT2 or EXT4 so then the whole system is faster all around and is a large improvement over stock rfs.
Click to expand...
Click to collapse
Ok so if make an ext partition, the apps that are stored in this partition will run faster. That sounds fair. Should I have both ext and FAT partions? And if I do, how does Android know where to put the apps? Also how about swap?

aventinus said:
Ok so if make an ext partition, the apps that are stored in this partition will run faster. That sounds fair. Should I have both ext and FAT partions? And if I do, how does Android know where to put the apps? Also how about swap?
Click to expand...
Click to collapse
No need for swap, and yes EXT is automatically recognized by android for a2sd, but make sure your ROM supports it. You would have an EXT partition between 256mb-2gb max, and then the rest would be FAT.

fowenati said:
No need for swap, and yes EXT is automatically recognized by android for a2sd, but make sure your ROM supports it. You would have an EXT partition between 256mb-2gb max, and then the rest would be FAT.
Click to expand...
Click to collapse
Ok! That was really eye-opening! Thank you so much!

no problem!

ICE DS v 4.2 ICS 4.0.4 Sense 3.6 with ext3

hello everybody!
I tried to find an answer on this on the ROMs thread but I couldnt so here it is;
Can I use ICE DS v 4.2 with ext3 only? If so, can I disable afterwards ext4 support?
Thanks

why wouldnt you use ext4? it's an advantage thou. but if you dont want to use ICE DS in future, just revert to ext3 by using 4EXT Recovery.

For the amount of internal memory that our devices have there is no matter whether you use ext3 or ext4. Also the install script of the ROM itself will format the partitions as ext4 upon flashing so there is not much choise actually If you like to go back to ext3 after flashing 4EXT Recovery can do this without losing any data
Sent from my HTC Desire S

Thanks for the quick replies..
When I used a stock ROM with a rooted Desire, I remember discussions about the disadvantages of ext4.
The idea as I understood, was that ext4 was more likely to create filesystem corruption in case of an abnormal shutdown of the phone, eg battery removal, expecially if it used to extend phone memory to the sd card via proper partitioning.

It is exactly the opposite. The ext4 file management will prevent corruption in case that a read/write process gets interrupted by a battery pull or similar. Search Google for ext4 there are all the benefits described on a Wikipedia article.
Sent from my HTC Desire S

amidabuddha said:
It is exactly the opposite. The ext4 file management will prevent corruption in case that a read/write process gets interrupted by a battery pull or similar. Search Google for ext4 there are all the benefits described on a Wikipedia article.
Sent from my HTC Desire S
Click to expand...
Click to collapse
This.
ext4 wouldn't exist, or developed if ext3 is better.

[Q&A] 2 GB External Data -- Hefe Hook Kernel and others

The Hefe Hook kernel allows you to mount a partition of your microSD as /data, getting 2 GB (or more) for your apps and their data.
Please ask your questions here about installation, use, or general approach.

This is great @jeffsf and can u show me how to re-partition the "real internal" storage? I mean expanding the /system since u put the /data out of it. Thanks man
Sent from my GT-N7000 using Tapatalk 2

daothanhduy1996 said:
This is great @jeffsf can u show me how to re-partition the "real internal" storage? I mean expanding the /system since u put the /data out of it.
Click to expand...
Click to collapse
Yes, you've hit on another of the reasons I've been exploring using the microSD for "live" storage. It's one thing to use potentially slow storage for photos that you basically write once or "app to SD" where you read the APK at boot time, make sure your ODEX in the Davlik cache is good, then generally read from the internal-flash cache. It is another when that memory is being read and written "constantly" when your phone is running.
The good thing is that once /data is not part of the internal flash filesystem, you don't have to worry about one ROM (kernel) thinking it begins at one place and another saying it starts at another. Previously, if one ROM had one /system size and another and a different one, the next partition, /data, would look to be corrupt when you swapped ROMs.
As a warning, not all users have fast microSD cards. Some that say "Class 10" on them really are dogs, especially for small reads/writes. The "Class" ratings are for sustained writes, as you would have with a camera recording video. If your ROM is "external /data" only, or even defaults to that, be prepared for a slew of "Your ROMs sucks. It is so slow." complaints.
You'll also need a way to automate formatting the card. It can be done on the phone, as long as you aren't trying to preserve any data.
As I recall, the layout of the MTD partitions is done in drivers/mtd/onenand/samsung_galaxys4g.h I would be careful not to move the partition boundary for efs, as you'd have to move the data it contains in your updater script. Repeating the warning about not moving the boot and recovery partitions is probably a good idea as well!
Your build tree may need some of these values, or at least think it needs some of these values. For example, device/samsung/aries-common from the CyanogenMod/cm-11.0 (KitKat) branch calls out NAND page sizes, partition sizes, and flash block sizes. I haven't looked in detail at your build tree so I can't comment on how it might handle things differently than the CyanogenMod one.

itzik2sh said:
Hi
I hope I don't ask anything silly, but please let me know if any of my assumptions is wrong :
1. I take FBi's251's AOKP milestone 6 (ICS 4.0.4)
2. 8GB SDCard was formatted to FAT32 (4GB) and EXT3 (4GB) using TWRP kernel
(Beastmode's proton kernel to be exact).
3. I would flash this kernel and it would move apps and their data to the sd-ext
without any special additions.
Thanks. I read the thread, but unfortunately 8GB SD is what i have and I think it should be enough.
Thanks again.
P.S - it's for 2 guys I already sold them my SGS4Gs. I want them to be happy...
Click to expand...
Click to collapse
AOKP should be fine. I haven't tried it recently, but it was the tree in which I did the early Hefe Kernel development.
As I understand it, you have a microSD with
partition 1: 4 GB FAT32
partition 2: 4 GB ext3
So that can work, but will need some tweaking of the init-on-fs.sh script. I intentionally didn't use the second partition as so many scripts gobble that up as sd-ext and do who knows what to it.
My first preference would be to reformat the cards, perhaps:
6 GB FAT32
1 MB ext2/3/4 (Yes, 1 MB, a sliver, choice of ext2, ext3, ext4 up to you)
2 GB ext4
since then the script will work without modification and if they install a third-party script that uses the second partition, it won't corrupt their data.
If you were to keep the formatting the way that it is now, you'd need to edit the mount commands in the script to look something like:
Code:
/system/xbin/busybox umount /data
/system/xbin/busybox mount -t ext3 -o noatime /dev/block/mmcblk0p2 /data
(removing the sd-ext mount)
I'm not sure what your expectations are, but all that the kernel and that script will do is mount a different disk partition on /data -- you need to manually move the data over (or restore from something like Titanium Backup). There may be some trickery in renaming that could be used with TWRP backups to restore from data.yaffs2.win to the new /data partition, but I haven't tried that at all.

Hi Jeff
Thanks for your quick reply, and sorry again for not seeing the Q&A thread.
I think making it :
partition 1: 4 GB FAT32 (sdcard)
partition 2: 2 GB ext3 (sd-ext)
partition 3: 2 GB ext3 (data)
partition 4: 1 MB (spare)
would be better and handle data as well. don't you think ?
Would it be worth doing with a "Team" micro-SD card (class 6 I believe) ?
Thanks.

I haven't tried a Class 6 card, but my gut feeling is that it will be dicey. I didn't "commit" to using /data on microSD until I had tried it for several days using Titanium Backup's ability to move both apps and app data to the external card. I would try that first, especially as the phones in question aren't going to be in your hands (I consider you an expert user, able to manage things outside the UI with ease).
I've attached some testing I did a while ago with Transcend and SanDisk cards. When you look at them, realize that the speed scale changes between them. I have a feeling that the real "performance" on a device is going to be related to relatively small reads and writes, not the ability to stream video to the card. I also don't know much about the Team brand, but I found that even some well-known brands didn't have the performance of the Transcend or SanDisk in the same category.
However you configure your cards, I would definitely recommend a journaling filesystem of some sort. I've had my microSD come loose inside the phone. The journal will at least help to reduce any filesystem corruption should that happen.
You don't need the fourth partition -- I have it there to be able to keep rsync backups for fast ROM swapping.
.

Regarding the apps data, have you tried exploring the Mount2SD script ?
sent from me

I've tried a couple of the scripts out there in the past. Since backing up my data is very important to me, I trust the scripts in Titanium Backup to work well with its backup/restore strategies.
Mounts2SD looks like it has gotten a lot more sophisticated than it was when I tried it in the past. It sounds like something worth trying in its current state. At a quick glance (and not looking at the code), I'd personally make some different choices about features; enabling journaling, and being concerned about why lost+found was filling up (things should only appear there if the file system is found to be corrupt).