Database Develop

Compcache or linux-swap partition

Ok so i am running Cyan's 3.6.8.1 currently. I was running the newest 7 up untill this morning. And i woke up and booted my phone and had extreme lag. Restarted, had some bad lag still. I checked my swap and it said 0 across the board. I cant remember checking it with a fresh install. So my question is:
Does swap partition work with the most recent cyanogens? Also i keep seeing stuff pop up about compcache, ive read the tutorial but it looks like there isnt a recent userinit.sh for the newest cyan rom. How much faster is compcache if any over the swap partition?

I may be wrong but ithink the difference is one is dumped on sdcard (swap) and the other internally (compcache). Thaty means a slower sd card would result in slower read/write times. Also giving more wear on the sd. The userinit posted should be fine with cyanogens newest, however swappiness seems to be set a little high (60) that is a endless debate for the perfect setting. Mine is set to 10 though.

I have been reading some conflicting posts over which is better (linux swap vs compcache). Having used compcache for a week now, I am not happy with it--my swappiness was originally set at 60 and is now at 20. Some are saying that the linux swap allows their phones to operate very quickly and smoothly, which is unfortunately not the case with my phone. Add the confusion that there is a solution involving compcache with a backing swap file, and things look really complicated.
Also, I actually saw a poster claiming that NO SWAP worked better than having a swap at all. If anyone has some real data, please tell us: 1) whether swap increases phone performance (and how), and 2) which swap (linux, compcache, or compcache with backing swap) is better.
Thanks!

derfolo said:
I have been reading some conflicting posts over which is better (linux swap vs compcache). Having used compcache for a week now, I am not happy with it--my swappiness was originally set at 60 and is now at 20. Some are saying that the linux swap allows their phones to operate very quickly and smoothly, which is unfortunately not the case with my phone. Add the confusion that there is a solution involving compcache with a backing swap file, and things look really complicated.
Also, I actually saw a poster claiming that NO SWAP worked better than having a swap at all. If anyone has some real data, please tell us: 1) whether swap increases phone performance (and how), and 2) which swap (linux, compcache, or compcache with backing swap) is better.
Thanks!
Click to expand...
Click to collapse
Compcache with backing swap uses both compcache and the linux swap partition (or a regular swap file). Because this uses both methods, this would be fastest. Its actually made the JACHero ROMs ridiculously usable (compared to before anyways...). The swappiness doesn't matter, it just determines how often android will use compcache or linux-swap. It differs from build to build, each build will have an optimal setting.
Linux-swap is faster than regular swap file.
I don't have any data, but testimonial(ly?) when I use JACHero with vs without compcache and linux-swap is like night and day. Without it, the phone is unusable, with it, the phone is very much improved.

Kind of off topic, but how do i change the size of the compcache file?

cronin4392 said:
Kind of off topic, but how do i change the size of the compcache file?
Click to expand...
Click to collapse
Edit the userinit.sh file you're using. Check the proper threads for compcache in development forums.
As far as Compcache vs swap, I've gone back to no swaps, it seems snappier by itself without these methods. It could be a personal preference though depending on what apps/services you use the most.

Using NAND as RAM?

After many tests I think that we really suffer from a lack of RAM. But the internal memory (NAND) should be the same speed as RAM I think. So why we don't use another 128Mb of NAND as additional RAM? A sort of swap part, but used as RAM and not as normal swap....
If someone related to the kernel would answer is it possible or not, it would be good)

DiMiK said:
After many tests I think that we really suffer from a lack of RAM. But the internal memory (NAND) should be the same speed as RAM I think. So why we don't use another 128Mb of NAND as additional RAM? A sort of swap part, but used as RAM and not as normal swap....
If someone related to the kernel would answer is it possible or not, it would be good)
Click to expand...
Click to collapse
Using it as RAM would propably require major changes to the kernel if it is even possible which I doubt it is. Using it as swap would be the possible alternative and I pretty sure that is very possible and would help performance but at a cost.
1. You would either have very little left for system and data or you would have to put system and/or data on the SD-card and that alone may make you lose anything you gain from putting swap on NAND.
2. I actually asked the swap-on nand question myself and well, we can't replace our NAND, at least not easily and swap is I/O intensive and intesive I/O will sooner or later wear out the NAND. So basicly this is not a good alternative unless you want to turn your phone into a paperweight sooner than you had planned.
So what we can do is using compcache and/or swap on SD-card. The easiest thing is to just enable some compcache. It uses RAM as swap and uses compression on the contents so we can hold more things in RAM that we would usually be able to. This means Android can keep more apps in "sleep" allowing for faster switching between apps but it will also decrease the possible amount of available RAM for the active app. I usually turn on compcache with the default setting which is to use 25% of the RAM for compressed swap. It might be placebo but IMHO it feels a it "smoother" to use after that.
Another alternative is to use a swap partition in the sdcard. Just using swap means you do not need to load any compcache kernel modules and there is no compression taking place so it's a good alterantive. However you need know your way around partitioning SD-cards to get this running so it's not as easy as just enabling compcache (assuming the build supports compcache).
For the really advanced you can enable compcache with backing swap. It means it uses a certain amount of compressed swap i RAM and when it runs out of space there it starts putting stuff on the SD-card swap partition. Once again, a bit tricky to setup but may be the best alternative.
Read more about it here: http://wiki.cyanogenmod.com/index.php/Compcache

kallt_kaffe said:
I usually turn on compcache with the default setting which is to use 25% of the RAM for compressed swap. It might be placebo but IMHO it feels a it "smoother" to use after that.
Click to expand...
Click to collapse
It make good effect: more applications can run simultaneously.

Making g1 run faster? (10 mb hack)

Hi, I was wondering if I can use the 10 mb ram hack with my g1 with CM 6.0 RC2. I noticed most of the tutoriials are using 4.xx.xx so I wanted to ask before I do it. My phone is kind of slow even though it is overclocked at 576mhz and 64 mb class 6 memory swap. Thanks.

Ties0 said:
Hi, I was wondering if I can use the 10 mb ram hack with my g1 with CM 6.0 RC2. I noticed most of the tutoriials are using 4.xx.xx so I wanted to ask before I do it. My phone is kind of slow even though it is overclocked at 576mhz and 64 mb class 6 memory swap. Thanks.
Click to expand...
Click to collapse
There is no 10 mb hack and won't be. It is not possible with Froyo.

As indicated above there is no 10mb hack and there never will be.
I am currently using the latest nightly and it is super fast and stable. As fast as donut (no ****).
3D Gallery works perfectly and there have been a bunch of small cool features added to the nightly.
I highly recommend it.
Awesome work has been done by Cyanogen and Crew.

ok thanks for the reply guys. Is there any other way to make my rom faster? Thanks.

Ties0 said:
ok thanks for the reply guys. Is there any other way to make my rom faster? Thanks.
Click to expand...
Click to collapse
Of course reduce or remove swap,
android has it's own swap mechanism that causes little ram to actually be least recently used, thus if swap is enabled the phone will be constantly swapping it in/out!
In addition to reducing the life of the SD card its slow. I understand a very little bit of swap *may* allow some edge cases where a *little* more ram is needed or to offload something like launcher that may be configured to stay in ram to work faster.. however you can't forget the speed issue.
Try this enter console on your phone and run:
dd if=/dev/zero of=/sdcard/swapspeedtest bs=1048576 of=64
Note the time it takes, that is the time to write 64mb on a swap out operation.. if it seems too long to wait for a task its too much swap. 12mb is almost acceptable. I just stick to comp cache only. . Upped it from the default 12 to 15 MB since I had one or two tasks that just needed a tad more memory to play nice.
Also what is slow, returning to home? A particular app? I doubt its everything, usually its launcher and there are ways of locking it in home, upgrades to awd, and alternative launchers. These may help.

ezterry said:
Of course reduce or remove swap,
android has it's own swap mechanism that causes little ram to actually be least used, thus if swap is enabled the phone will be constantly swapping it in/out
In addition to reducing the life of the SD card its slow. I understand a very little bit of swap to allow some edge cases where a little more ram is needed or to offload something like launcher that may be configured to stay in ram.. however you can't forget the speed issue.
Try this enter console on your phone and run:
dd if=/dev/zero of=/sdcard/swapspeedtest bs=1048576 of=64
Note the time it takes, that is the time to write 64mb on a swap out operation.. if it seems too long to wait for a task its too much swap. 12mb is almost acceptable. I just stick to comp cache only. . Upped it from the default 12 to 15 MB since I had one or two tasks that just needed a tad more memory yo play nice.
Also what is slow, returning to home? A particular app? I doubt its everything, usually its launcher and there are ways of locking it in home, upgrades to awd, and alternative launchers. These may help.
Click to expand...
Click to collapse
Thanks for the detailed response! I will try lowering the swap partition, I always thought it would be fast because of the class 6 speeds. Does putting all my apps on SD make it slow as well? Also, returning to home is the main lag I'm talking about as it takes quite a while to see my apps. Thank you!

ezterry said:
Of course reduce or remove swap,
android has it's own swap mechanism that causes little ram to actually be least used, thus if swap is enabled the phone will be constantly swapping it in/out
In addition to reducing the life of the SD card its slow. I understand a very little bit of swap to allow some edge cases where a little more ram is needed or to offload something like launcher that may be configured to stay in ram.. however you can't forget the speed issue.
Try this enter console on your phone and run:
dd if=/dev/zero of=/sdcard/swapspeedtest bs=1048576 of=64
Note the time it takes, that is the time to write 64mb on a swap out operation.. if it seems too long to wait for a task its too much swap. 12mb is almost acceptable. I just stick to comp cache only. . Upped it from the default 12 to 15 MB since I had one or two tasks that just needed a tad more memory yo play nice.
Also what is slow, returning to home? A particular app? I doubt its everything, usually its launcher and there are ways of locking it in home, upgrades to awd, and alternative launchers. These may help.
Click to expand...
Click to collapse
I have about 3-5 apps that I would like to be running at one time? Should I be using CompCache or Swap? Currently I am on SuperD 1.9.3 WGK. I have been reluctant to run Froyo roms because they are so much more memory hungry in my experiences. My current rom runs pretty fast with a 96mb swap. If I were to fun a Froyo rom, what can I do to be able to run the 3-5 apps and retain speed?

Ties0 said:
Thanks for the detailed response! I will try lowering the swap partition, I always thought it would be fast because of the class 6 speeds. Does putting all my apps on SD make it slow as well? Also, returning to home is the main lag I'm talking about as it takes quite a while to see my apps. Thank you!
Click to expand...
Click to collapse
If you are using BOTH SWAP & have applications installed to the sdcard, then it will ****REALLY**** be slow.
With just applications on the sdcard, your speed should be fine.

Ties0 said:
Also, returning to home is the main lag I'm talking about as it takes quite a while to see my apps. Thank you!
Click to expand...
Click to collapse
This is a symptom of launcher being evicted from ram, try the stay in ram option in settings->adw launcher->system settings->system persistent in the more recent versions of adequate (I think included with rc2 if my memory serves me)
It may not be perfect as it will still get killed if a very large application is loaded.
Either you need a launcher that behaves as a good android application, and can quickly reload it's last state, even if it was not in ram when you requested it.. or launcher needs to be considered outside the usual android memory management and to be kept in ram.
These persistent processes are where you may depending on your usage of the phone find comp cache or swap in low amounts (32mb combined is probably the absolute max) may help as they will have allocated ram that is rarely used and not automatically freed as they are persistent..

ezterry said:
This is a symptom of launcher being evicted from ram, try the stay in ram option in settings->adw launcher->system settings->system persistent in the more recent versions of adequate (I think included with rc2 if my memory serves me)
It may not be perfect as it will still get killed if a very large application is loaded.
Either you need a launcher that behaves as a good android application, and can quickly reload it's last state, even if it was not in ram when you requested it.. or launcher needs to be considered outside the usual android memory management and to be kept in ram.
These persistent processes are where you may depending on your usage of the phone find comp cache or swap in low amounts (32mb combined is probably the absolute max) may help as they will have allocated ram that is rarely used and not automatically freed as they are persistent..
Click to expand...
Click to collapse
Thanks for the detailed response! I just changed the adw launcher and deleted my swap partition... It seems to be much slower when pressing home (icons are taking a while to load) so I might just use 32 mb for swap.
EDIT: question, what exactly does ext4 do? I know swap is like external ram, but what does ext4/ext3/etc exactly do? and how much should I put in? I tried googling but could not find the answer. Thanks!

Ties0 said:
EDIT: question, what exactly does ext4 do? I know swap is like external ram, but what does ext4/ext3/etc exactly do? and how much should I put in? I tried googling but could not find the answer. Thanks!
Click to expand...
Click to collapse
On CM6, nothing. On CM 4 & 5, it was used for Apps2Ext (formerly known as Apps2SD - before Google came out with their own flavor). However, CM6 does not have Apps2Ext. It has been indicated that it will be targeted for 6.1.

Compcache

Just curious, I've been flashing the latest nightlies and in the cyanogenmod settings I see 'use compcache'. I have it unchecked, any difference if I check it. I found a you tube video about 2 phones running with and without compcache. Compcache seemed to load pages better over time, but not initially. Any help would be much appreciated

Copied from this post on another thread..
Very roughly you have a finite amount of memory (RAM). When memory is accessed it is virtual addressing, so an application is given a piece of memory, but this isn't real RAM, the operating system manages this and maps it to where the data really is. Because of this system, the OS can give out more memory than is actually available. It can then store some of this memory on a storage medium and "swap" it with some other programmes memory when one is needed and the other isn't. This is how swap works.
With compcache, instead of storing the dormant memory on a hard disk it is compressed and stored in the RAM itself on a virtual disk. This takes up some RAM, but because it is compressed, more RAM is spare tha n if the data were left in memory as it is. Again this has the effect that more memory space can be handed out than the RAM that is really there.
Because Android manages applications so that when memory runs out it just closes applications running in the background, more applications can reside in the larger virtual memory space than before, making multi-tasking more pleasant and responsive.

I know that nfinitefx45 took compcache out of his latest builds in both the Stock and ZenHeroFX ROMs. I don't know all the technical reasons behind it, but I think it just didn't improve performance enough to be worth leaving it in. Granted those are Sense-based ROMs though which are generally a little slower and "bloatier" in nature than AOSP, so the performance difference maybe be greater in CM.

chromiumleaf said:
I know that nfinitefx45 took compcache out of his latest builds in both the Stock and ZenHeroFX ROMs. I don't know all the technical reasons behind it, but I think it just didn't improve performance enough to be worth leaving it in. Granted those are Sense-based ROMs though which are generally a little slower and "bloatier" in nature than AOSP, so the performance difference maybe be greater in CM.
Click to expand...
Click to collapse
Thank you for the response, just wasn't sure. Since Darch left it unchecked, I figured I would ask

[Q] Would enabling swap boost real world performance?

I'm interested in any real world experiences of people using a swap partition on the SD card or similar solutions. I mostly see guides about how you enable swap, which isn't that hard, but any quantifiable or subjective reports of improved performance is lacking.
My only experience using swap was using an openwrt router (with very limited resources) where it was vital for some stuff to function at all, but I couldn't see any general speed improvements, and when swap was used it was terribly slow.
Do you use swap or tried it, does it help? How much?

PremiumMediocre said:
Do you use swap or tried it, does it help? How much?
Click to expand...
Click to collapse
Apparently this is not something that interest people, but in case someone searches for swap and finds this post I can say it definitely helps with multitasking. Currently my phone uses over 100MB of swap space, and lags due to apps being terminated due to low memory is a more rare occurrence nowadays.

Just some interesting reading about this:
http://zerocredibility.wordpress.com/2009/08/24/why-android-swap-doesnt-make-sense/
http://android.stackexchange.com/questions/2310/how-will-a-swap-partition-file-affect-the-system
If you're still interested, read these two links. A bit old though, but the only difference might be that Google has put an effort into making Android's way of freeing memory better. In that case, from what they say, I'd say there's a chance that swap will increase your performance.

Thank you, I've been reading up on swap as well, and it's not completely clear cut.
From your first link the argument:
"Having swap actually prevents the native Android memory management scheme from activating. The system sees memory and doesn't distinguish between physical and virtual. It will therefore prefer swap over the native Android memory management scheme, and won’t activate the native scheme until swap is full."
I believe this is just plain inaccurate. Even if you set swappiness to 100 android will terminate apps without filling the swap space, and swap is never treated as plain ram as far as I know.
Some real benchmarks is sourly needed though.

PremiumMediocre said:
Thank you, I've been reading up on swap as well, and it's not completely clear cut.
From your first link the argument:
"Having swap actually prevents the native Android memory management scheme from activating. The system sees memory and doesn't distinguish between physical and virtual. It will therefore prefer swap over the native Android memory management scheme, and won’t activate the native scheme until swap is full."
I believe this is just plain inaccurate. Even if you set swappiness to 100 android will terminate apps without filling the swap space, and swap is never treated as plain ram as far as I know.
Some real benchmarks is sourly needed though.
Click to expand...
Click to collapse
I tried to find done benchmarks, but it seems like there are none...
And like I said, old links so Google might have done something about the issues they're talking about
Sent from my Incredible S using xda app-developers app

Also have a look in the desire Z section for this. They only have 512mb ram (we have 768) so they are always looking for ways to free up ram
There is a lot of discussion about swap so have a look there They might know a lot more compared with us

markj338 said:
Also have a look in the desire Z section for this. They only have 512mb ram (we have 768) so they are always looking for ways to free up ram
There is a lot of discussion about swap so have a look there They might know a lot more compared with us
Click to expand...
Click to collapse
I think the speed of the processor is also important in this context since the native way to save memory is letting programs recreate the last state they were in before they were shut down. A fast processor would make swap less attractive.
In case you anyone wants to try, I'm using the Hunterwu kernel and used swapper 2 to activate the swap partition. The only hang up setting it up was that swapper 2 identified the wrong partition as swap but that could be manually changed.

PremiumMediocre said:
I think the speed of the processor is also important in this context since the native way to save memory is letting programs recreate the last state they were in before they were shut down. A fast processor would make swap less attractive.
In case you anyone wants to try, I'm using the Hunterwu kernel and used swapper 2 to activate the swap partition. The only hang up setting it up was that swapper 2 identified the wrong partition as swap but that could be manually changed.
Click to expand...
Click to collapse
Tell us if its any better, I might do the same