Database Info

Memhack

There are various mentions of a "memhack" to apply to the Milestone which apparently frees up some RAM. It also apparently can cause problems when flashing a different SBF.
Could someone help me out here by clarifying exactly what the memhack does and what are the circumstances under which it can cause problems?

Looks like this never got an answer, but now I'm seeing that some of the custom nandroid backups here make reference to using memhack. Could someone help me clarify this? I find a lot of Google hits but no explanations except in German... and it doesn't translate very well.

memhack does not free RAM but storage space. It simply moves the cache partition so you get more space for installing apps. As long as you wipe everything when restoring different nandroid backups, I don't think you can really have any issues. Also I don't really think it can affect your ability to flash SBF's. Maybe OTA updates could only be affected as cache gets moved where OTA upgrades are supposed to be downloaded and unpacked.

cmstlist said:
Looks like this never got an answer, but now I'm seeing that some of the custom nandroid backups here make reference to using memhack. Could someone help me clarify this? I find a lot of Google hits but no explanations except in German... and it doesn't translate very well.
Click to expand...
Click to collapse
If you open the script, if I recall correctly, it tries to move the dalvik-cache from the system partition to the cache partition, thus saving you space on the system partition.

i believe the latest version of apps2sd does this automatically ? i've got apps, apps-private and dalvik-cache on my sd card now...

somethingdope said:
i believe the latest version of apps2sd does this automatically ? i've got apps, apps-private and dalvik-cache on my sd card now...
Click to expand...
Click to collapse
Yeah, if you have apps2sd you don't need to apply memhack. In fact, it might mess up your device since the symbolic links for dalvik-cache should be pointing to the SD card, not the cache partition.

Thanks for clarifying. I'm starting to run low on app space on my Milestone but I'm not keen to use the apps2sd hack as I've heard it can cause all sorts of trouble. Not impressed that official Froyo is so far away.

cmstlist said:
Thanks for clarifying. I'm starting to run low on app space on my Milestone but I'm not keen to use the apps2sd hack as I've heard it can cause all sorts of trouble. Not impressed that official Froyo is so far away.
Click to expand...
Click to collapse
It's really not that hard once you understand how all of these things work. "Memhack" is too 'scary' a name for a simple thing.

dsixda said:
Yeah, if you have apps2sd you don't need to apply memhack. In fact, it might mess up your device since the symbolic links for dalvik-cache should be pointing to the SD card, not the cache partition.
Click to expand...
Click to collapse
this is not correct.. its actually a worst case scenario, and /dalvik-cache should only be on sdcard, when you're a apps hungry person that cannot work with 100MB free for the purpose..
current disadvantages on milestone for using dalvik on sdcard;
- unstable and slow ext2 kernel module..
- lacks direct io support
- slows phone if sdcard is class2 only.
- no support for wipe of /dalvik-cache folders with any current recovery.
- not a solution if no sdcard is present or paritioned correctly.
(suddenly /data is full?)
Advantage over sdcard pointers for dalvik are;
- faster seek times
- faster loading
- easier cleanup if required when switching roms
- still works even without sdcard inserted.
but if people dont care or know the consequences of their changes, they just accept.

Dexter_nlb said:
this is not correct.. its actually a worst case scenario, and /dalvik-cache should only be on sdcard, when you're a apps hungry person that cannot work with 100MB free for the purpose..
current disadvantages on milestone for using dalvik on sdcard;
- unstable and slow ext2 kernel module..
- lacks direct io support
- slows phone if sdcard is class2 only.
- no support for wipe of /dalvik-cache folders with any current recovery.
- not a solution if no sdcard is present or paritioned correctly.
(suddenly /data is full?)
Advantage over sdcard pointers for dalvik are;
- faster seek times
- faster loading
- easier cleanup if required when switching roms
- still works even without sdcard inserted.
but if people dont care or know the consequences of their changes, they just accept.
Click to expand...
Click to collapse
I actually didn't experience any performance gain or loss when moving my dalvik cache to my Class 6 card. I also have no need to remove my SD card. Of course most people should be aware that moving anything to SD requires at least a Class 6 (usually) if you want any kind of performance.

dsixda said:
I actually didn't experience any performance gain or loss when moving my dalvik cache to my Class 6 card. I also have no need to remove my SD card. Of course most people should be aware that moving anything to SD requires at least a Class 6 (usually) if you want any kind of performance.
Click to expand...
Click to collapse
Classes don't mean much for SD cards. They do to an extent, but in the end you really need to rely on benchmarks.
Class simply means minimum speed. A Class 6 card could run as slow as 6 MB/sec or go as fast as 20 MB/sec. Not sure.
I have a Sandisk Class 4 8gb microSDHC card. I saw the 16gb benched at 15MB/sec or so. I can hit 18-19MB/sec on mine.
This is considerably faster than the 16gb Class 2 that my Milestone shipped with. It's also considerably faster than the 16gb Class 6 Transcend I wanted to get. But remember my Class 4 promises 4 MB/sec transfers. These speed tests I've done are pretty darn fast.
Another example is my Class 6 Transcend 16gb SDHC (not micro) for my Canon Rebel camera. I benched it around 8.9 MB/sec. That's within Class 6 limits, but presumably my Class 4 8gb microSDHC Sandisk mounted on an adapter should do even better fine if I was able to bench it at 18 MB/sec on my computer....
So it's hard to say. If a Class 2 is really Class 2 at its minimum 2mb/sec, that's a pretty darn slow card.

Ok well I was getting close to that 20 MB "low memory" threshold so I memhacked using GOT OpenRecovery 1.04a. Nandroid backup first of course. Available space has skyrocketed to 91 MB! Sweet.

Anyone try this SD Card speed hack on the x10?

I wonder if this would work on the x10, anyone try it?
http://forum.xda-developers.com/showthread.php?t=1010807
UPDATE:
svtfmook has the info on how to do this via scriptmanager here
http://forum.xda-developers.com/showthread.php?t=1013554

Bialynia said:
I wonder if this would work on the x10, anyone try it?
http://forum.xda-developers.com/showthread.php?t=1010807
Click to expand...
Click to collapse
there is app for this in the market. i use it to speed up my sd card reading

i tried manually applied it but failed.. lol. use the apps sdcard booster instead.. working fine.. noticeable speed increase.

Crocodile1973 said:
there is app for this in the market. i use it to speed up my sd card reading
Click to expand...
Click to collapse
I'm running 2.1 rooted, the market app is 2.2 and above, won't show up for me.

u can try manually apply it.
/sys/devices/virtual/bdi/17:1/read_ahead_kb
change the value inside the read_ahead to 2048 or 3072
the italic, im nt sure its 17:1 or 17, something bout 17 im sure. inside got the read ahead
tis method however, change back to default after reboot

I tried the hack. Changed cache size from 128 to 2048. Write speeds stayed the same, but read speeds went up by about 5Mb/s. My SD card is crap tho, only a class 2. I also only tried the one cache size.

How big of a difference is noticeable between class 2 and class 6?........thinkin bout gettin rid of my class 2 16g if it makes a big improvement
Sent from my X10 using XDA App

Pretty noticeable, using a class 6 16gb increases all data retrieval speed eg contacts, pictures, apps on SD etc. Defo worth it.
Sent from my X10i using XDA App

Thanks...grabbing one today.....haha on sale for $30...... cant go wrong
Sent from my X10 using XDA App

any solution for this on GENERIC X10i 2.1.1.A.0.6 ??

Using app on froyo 2.2 phone feels smoother
Sent from my X10i using XDA Premium App

I have set it up to 2048 and it i have see a large affect of the speed of sd card.... But when my device reboot it is again at 128....Any idea to set it up permantely ?

pficrx said:
I have set it up to 2048 and it i have see a large affect of the speed of sd card.... But when my device reboot it is again at 128....Any idea to set it up permantely ?
Click to expand...
Click to collapse
Using the app i can set at boot
Sent from my X10i using XDA Premium App

there is no init.d on stock x10, so i set the file "99sdcardreadfix" to "run as root" and "run at boot" with "script manager" (free available at market).
The code working for me:
Code:
#!/system/xbin/sh
if [ -e /sys/devices/virtual/bdi/179:0/read_ahead_kb ]
then
/system/xbin/echo "[COLOR="Red"]3072[/COLOR]" > /sys/devices/virtual/bdi/179:0/read_ahead_kb;
fi
3072 was working best for me with the stock sd card.
read: 3,8
write: 73,4
If another value works better with your sd card, just change the red number to what you need

My best results
I have a SA32G (32GB) and the best results i got where with the buffer at 3456KB. Let me know if that works for anyone and if you find it helped let me know with a quick click on the 'thanks' button!
@Eisel89 Whats the ending on the 99sdcardreadfix? is it just a .bat? thanks

pp085ster said:
I have a SA32G (32GB) and the best results i got where with the buffer at 3456KB. Let me know if that works for anyone and if you find it helped let me know with a quick click on the 'thanks' button!
@Eisel89 Whats the ending on the 99sdcardreadfix? is it just a .bat? thanks
Click to expand...
Click to collapse
there is no ending to this file.
simply 99sdcardreadfix without dot and ending

i posted this in the general forum last week
http://forum.xda-developers.com/showthread.php?t=1013554
for 2.2 roms, you need to edit the script because echo is in bin, not xbin
download and use scriptmanager from the market, it will allow the script to run at boot.
works great on my 2.1 and 2.2 roms.
devs are not including this in their roms and no scripts are needed.

Thanks! That really did the trick for me, I am set at 1024 now, read speeds went up slightly between 6-7 mb/s while read speeds are around 25mb/s. I could get higher read speeds at higher cache but my write speeds would go down

thread carefully
Hi
I just wanted to point out that read ahead buffer is not a real SD card performance booster. It is the way how your OS handles card reading and buffering data. I agree that illusion of speedup is present and large data set can really benefit from big read ahead buffer (like video audio and some others).
If you try other SD speed test applications like "Sst" aka "SD Card Speed Test" changing read ahead buffer will not make a dent because software is not using buffers to test real performance.
In some cases big buffer can really degrade performance because OS is cashing something that was not needed.
So my advice is to thread carefully and make read ahead buffer bigger only if you suffer from dropped frames in video or audio players, games and if you use app2sd.
Real performance boost can only obtained with better SD card driver if possible (custom kernel) and better SD card class 6 if possible. (not all SD card's regardless of class will not work in your device as expected eg. Kingston SanDisc Apacer and others research before you buy)
Kradovan

kradovan said:
Hi
I just wanted to point out that read ahead buffer is not a real SD card performance booster. It is the way how your OS handles card reading and buffering data. I agree that illusion of speedup is present and large data set can really benefit from big read ahead buffer (like video audio and some others).
If you try other SD speed test applications like "Sst" aka "SD Card Speed Test" changing read ahead buffer will not make a dent because software is not using buffers to test real performance.
In some cases big buffer can really degrade performance because OS is cashing something that was not needed.
So my advice is to thread carefully and make read ahead buffer bigger only if you suffer from dropped frames in video or audio players, games and if you use app2sd.
Real performance boost can only obtained with better SD card driver if possible (custom kernel) and better SD card class 6 if possible. (not all SD card's regardless of class will not work in your device as expected eg. Kingston SanDisc Apacer and others research before you buy)
Kradovan
Click to expand...
Click to collapse
gallery loads faster, access times are reduced, it's not an illusion and it is an improvement without sacraficing anything else.

Memory stored on external instead of internal

i just thought about ROM's made to store memory on SD cards instead of being stored internaly. can anyone explain y it wouldnt work or y anyone hasnt done it yet?

also wanted to add, by doing this change of memory storage it would speed up the system by 50%. it would also be a + for people who play video games on their smart phones Zonia, Inotia, MMO's ect"""

An SD card, or any format of memory card for that matter, can only be used for the storage of data. It behaves like a hard disk. Data on it must be serially 'read' into a main memory buffer, before it can be accessed by your device's processor.
You can't replace 'real' memory with it or try to use it as real memory.

hijack562 said:
doing this change of memory storage it would speed up the system by 50%
Click to expand...
Click to collapse
why?
10 characters

so cant you partition a sd card to be used as real memory? or can it be possible to compress real memory?
and why you ask? cuz it would be nice to play games on a smart phone that only comes with 200mb or less memory. but has a fairy decent processor

Too Slow
The reason they don't do that is because SD cards are MUCH slower than memory. the fastest SD cards (Class 10) only transfer data at 10 MB/s. Memory on the other hand transfers data in the range of gigabytes per second. Even if the memory used a very "slow" rate of 1GB/s that is still 100x faster than a SD card is.

really?? a class 10 only reads 10mb per sec?? dam thats slow...but isnt a sd card consider a soild state drive or not?

Take a close look at an SD card. It only has 9 pins on it. In standard mode two of them aren't used, leaving 7. After 1 x Chip Select, 1 x Power, 2 x Ground, and 1 x Clock, that leaves two pins - namely 1 x Data In and 1 x Data Out.
Not a 32 bit data/address bus like an x86 or ARM processor, but a single, one bit wide bus.
A byte of stored data comes out of the Data Out line as 8 bits, one at a time.
Commands to the card, to ask it to retrieve/store the data you want, have to be sent down the Command/Data In line the same way. Data to be written to the card goes in down the same Data In line the same way, again one bit at a time.
Even though the clock rate can, in theory, be wound up to 25Mhz, it is still a tedious process to get data in and out of the thing.
True solid state drives use the SATA interface, a different type of interface, still serial as above, but the clock rates are much, much higher allowing 1.5 to 6.0 GBit/s transfer rates.
Memory cards can be considered solid state drives, just damned slow ones.

Sorry if this isn't directed towards OP but since we are talking about SD cards anyways I thought I'd ask. Any way to tell what class your SD card is? I have a 16GB one so I'm assuming its class 10.

New cards have the class number on the label, as Class n, or as a capital 'C' with the class number in it.

Samsung 64GB SD Card - SO SLOW

So I ordered a Samsung 64GB Class 10 micro SD card, and it seems VERY slow.
While I gone so much mind the slowness, as I dont play a lot of games and would use it more for pictures and music I was wondering if I could get a few questions answered before I send it back or just give it to someone else.
1: Does the S4 have problems with 64GB cards?
- I am running Sacs KitKat V2
2: should I format with a format (NSFT/exFat) and is it better done on a Mac or PC?
3: what should the Unit Size be?
4: I just copied my old sd card on to this one, and some of the big games I do have stopped showing up. but when I put my old card back in, they are there again.
Why would this happen?
Thanks for the help everyone!

You have to format the card using the phone itself. Go into settings then storage and the option should be there. Try that, then re-copy your stuff to the card. If you still have problem then it is probably a dud card.
Sent from my SAMSUNG-SGH-I717 using xda app-developers app

You shouldn't re-format it at all from stock, but if you do you should try the official SD Formatter: https://www.sdcard.org/downloads/formatter_4/
I have a samsung 64GB microsd in my S4 and it's ridiculously fast according to SD Tools (http://i.imgur.com/EXUVIP7.png), probably a caching causing that; but anyways, it's great in normal use copying roms over/etc.

Oishikatta said:
...probably a caching causing that
Click to expand...
Click to collapse
LOL, you don't say! Divide those numbers by 10 and you have a more realistic speed indication :good:

Pfeffernuss said:
LOL, you don't say! Divide those numbers by 10 and you have a more realistic speed indication :good:
Click to expand...
Click to collapse
No, samsung does claim the card gets 70MB/s read and 20MB/s write - and the reviews on amazon match that even for the lower priced card:
http://www.amazon.com/Samsung-64GB-PLUS-Micro-Adapter/dp/B00I4ZMNY4/
Obviously the SD Tools benchmark isn't testing the actual card performance, but what matters is that in actual use the samsung cards are great.
Windows/crystaldiskmark can also easily be used to do a real test.
Here's in a usb 2.0 card reader:
Sequential Read : 23.455 MB/s
Sequential Write : 17.352 MB/s
Random Read 512KB : 22.898 MB/s
Random Write 512KB : 16.407 MB/s
Test : 100 MB [D: 32.1% (18.8/58.5 GB)] (x5)
Date : 2014/03/26 11:16:15
OS : Windows 8.1 [6.3 Build 9600] (x64)
If @chaos67731 isn't getting at minimum 10-20MB/s after formatting the card then there's probably something wrong with it.

chaos67731 said:
1: Does the S4 have problems with 64GB cards?
- I am running Sacs KitKat V2
2: should I format with a format (NSFT/exFat) and is it better done on a Mac or PC?
3: what should the Unit Size be?
4: I just copied my old sd card on to this one, and some of the big games I do have stopped showing up. but when I put my old card back in, they are there again.
Click to expand...
Click to collapse
1: A good amount of users (including me) had problems with their SD cards on S4s. The problems are between:
occasional unmount/remount (the system does this for no apparent reason). S4 cant read cards after a sudden unmount, and cards usually get killed. most of the cards reported are 16,32 and 64 GB micro SD kingstone. SandDisk has problems too but I'm not sure about Samsung's.
2: Just use the official SD formatter mentioned by @Oishikatta above.
3: if you used the official SD formatter you wont have to deal with Unit Size. (personally, I dont know what's that)
4: Do you use a card reader when you copy your memory card? or do you just connect the phone using a cable? try using a card reader when copying your SDs. Some hidden files may not appear if you used the cable.
I hope I helped and excuse my English, its not my native language.

Well if you have a SanDisk they want you to format exfat. http://kb.sandisk.com/app/answers/d...sion/L3RpbWUvMTM5NTg5ODI5OS9zaWQvRDdTTFVmUWw=

Oishikatta said:
No, samsung does claim the card gets 70MB/s read and 20MB/s write.
Click to expand...
Click to collapse
Sure, on a PC with an appropiate very fast SD-card reader. Using a phone you won't get those advertized speeds.
This is the result with a more proper SD-benchmarking app (although internal and external SD are shown in reverse):
These values will be more realistic. SD-Tools results (cached) don't mean jack, unfortunately.

Rooted phone: requesting info re: ext partition size, type of ext, and others

Hi:
I am a newbie, but I've learned a lot about things using this site and others. Thank you!
I have a rooted LG Volt, which of course has the odious KitKat restrictions on putting apps on SD cards. I've read about mini-tools and have Link2SD (premium, so I can link everything to the SD), but haven't tried it out yet because I wanted to ask some questions first. For reference, I have a 16g (class?) 10 SD card, which I've verified is legit using an app (forgot name).
1) Is there a maximum size for the second (ext) partition? I've read 2g, but other sites have said that there are now no restrictions. 2g is quite small for me since the Volt has very little internal memory, and I download a ton of apps; I don't use as much data. Ideally, I'd like to go half and half (approx. 8/8g data/app partition).
2) If it is limited to 2g, is there any workaround that doesn't require a ton of knowledge? I read something about changing system apps to user apps, but would this work--and is there a noob-friendly walk through?
3) Is there a preferred ext partition type? Again, I've read varied opinions; most say that ext2 is optimal, but others say ext4 might work better with Link2SD.
4) Is there any advantage to using a swap file? Again, varied opinions, but it seems mostly beneficial in terms of speed, and not to a degree that it matters.
I have other questions regarding partition alignment (found a calculator, so I think I can figure out how to optimize the partitions) and will probably have more in the future, but I would really love answers (or else links to answers) about these issues.
Thanks in advance!

anoukaimee said:
Hi:
I am a newbie, but I've learned a lot about things using this site and others. Thank you!
I have a rooted LG Volt, which of course has the odious KitKat restrictions on putting apps on SD cards. I've read about mini-tools and have Link2SD (premium, so I can link everything to the SD), but haven't tried it out yet because I wanted to ask some questions first. For reference, I have a 16g (class?) 10 SD card, which I've verified is legit using an app (forgot name).
1) Is there a maximum size for the second (ext) partition? I've read 2g, but other sites have said that there are now no restrictions. 2g is quite small for me since the Volt has very little internal memory, and I download a ton of apps; I don't use as much data. Ideally, I'd like to go half and half (approx. 8/8g data/app partition).
2) If it is limited to 2g, is there any workaround that doesn't require a ton of knowledge? I read something about changing system apps to user apps, but would this work--and is there a noob-friendly walk through?
3) Is there a preferred ext partition type? Again, I've read varied opinions; most say that ext2 is optimal, but others say ext4 might work better with Link2SD.
4) Is there any advantage to using a swap file? Again, varied opinions, but it seems mostly beneficial in terms of speed, and not to a degree that it matters.
I have other questions regarding partition alignment (found a calculator, so I think I can figure out how to optimize the partitions) and will probably have more in the future, but I would really love answers (or else links to answers) about these issues.
Thanks in advance!
Click to expand...
Click to collapse
First of all, you haven't told us what are you trying to do. If you are just trying to get a few questions anwsered just say so.
From what I see you are trying to use Link2SD because of the kitkat sd card restriction?
Note: Apps can't detect if an SD card is fake. It will just test how fast it is and guess if it's fast engough for it's class
You can remove the KitKat SD restriction with this app: SDFix
1) Yes, there is a restriction but it depends on how it's formated: on ext2 and 3 the limit is 35184 GB on a single partition and ext4 has a max limit of 1152921500 GB.
2) It's not limited to 2GB. Changing system apps to user and user to system is useless and should not be done if you don't know what exactly and why you are doing it. Don't let root fool you. Deleting system apps will NOT give you more free space for all the games.
3) Depends on support. If your phone supports ext4 (and it does) use that if not use lower such as ext3 then 2 and so on.
4) Look at this as a glass and some water. Water is memory to be put in ram and the glass is the ram your phone has.
The more water you put in it, the less space there is. And when it's full it will overflow, and your phone will freeze or reboot.
What swap does is when the water overflows in the glass (the ram gets full), the water (memory) that overflows goes to a swap file instead of it just getting lost and the phone getting frozen.
But remember, any SD card is MUCH SLOWER that RAM and using swap will not give any preformacne improvments.
The swap sould be factory set anyways and it also uses a lot of storage.
You REALLY shouldn't mess with the partitions.
You could break your phone forever.
What I recommend using is FolderMount and GL2SD. FolderMount is exactly like Link2SD, but you don't need to do any fancy partitioning. And GL2SD works great too, the only downside is that you have to run the apps (you moved to SD) from within the app.

Thank you!
Wonderful, clear answers! Yes, just trying to figure out "what to do" so I can add more apps to the Volt in the easiest manner possible. Apologize for not being clearer about that.
Just some follow-up questions:
1) will the app cited above (nextapp) allow me to move apps to the sd, or just data? Never having had an android other than this one with the dread KitKat, I don't know how it typically works after a KitKat fix. So should I format the entire sd card as FAT32 or ext4 (is the latter even possible)? And where will the data that I do have be saved if I don't partition the card? All on the one partition?
2. RE: FolderMount and GL2SD: that sounds great. The one concern that I have is that Link2SD's support (I THINK that's where I found this) said that the problem with putting an app on an sd card versus linking it is that if you take the sd card out, all of the apps will be gone. Is that just incorrect?
Thanks again! Very helpful.