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Poor performance writing on /data

OP monossidoz

4th December 2012, 04:12 PM   |  #1  
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Hi all
My Galaxy Nexus with CM10 a week ago has started to lag a little bit, and the situation was getting worse day by day...
wipe didn't solve anything

so I tried to run some benchmark in order to understand if it's an hardware problem

with androbench I noticed that the write values are ridiculous

what can I do before bring it back to the manufacter?
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4th December 2012, 05:12 PM   |  #2  
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When did you buy your Galaxy Nexus?
Can you please post a screenshot of the following App: http://forum.xda-developers.com/show....php?t=1693704

Maybe you're affected by this bug:
http://code.google.com/p/android/issues/detail?id=39154
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4th December 2012, 05:55 PM   |  #3  
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Mine has similar results with androbench and is 2 weeks old. I have not deleted any big files also. The gotbrick app says that my emmc chip is unknown.

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4th December 2012, 06:06 PM   |  #4  
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Quote:
Originally Posted by mariosraptor

The gotbrick app says that my emmc chip is unknown.

Is it a chip of type V3U00M?

You may try to remount /data and /cache (probably also /system) with the discard option and use dd/rm or Forever Gone to erase the empty blocks as suggested beginning at comment #25.
http://code.google.com/p/android/iss...l?id=39154#c25
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4th December 2012, 06:09 PM   |  #5  
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Quote:
Originally Posted by ph4zrd

Is it a chip of type V3U00M?

You may try to remount /data and /cache (probably also /system) with the discard option and use dd/rm or Forever Gone to erase the empty blocks as suggested beginning at comment #25.
http://code.google.com/p/android/iss...l?id=39154#c25

Yes, is V3U00M. I read the comments there. I will try forever gone. Thank you

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4th December 2012, 06:30 PM   |  #6  
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Quote:
Originally Posted by ph4zrd

Is it a chip of type V3U00M?

You may try to remount /data and /cache (probably also /system) with the discard option and use dd/rm or Forever Gone to erase the empty blocks as suggested beginning at comment #25.
http://code.google.com/p/android/iss...l?id=39154#c25

yes, V3U00M!
I'll try the solution with adb (remount, dd and rm) later.

Thank you!
4th December 2012, 07:03 PM   |  #7  
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I just finished the forever gone solution. Tbh it is now worst than before.
Androbench took ages to finish and half the results.
So, to summirize. We should not try any solutions like this or via adb or any other that will make the device perform more slowly.
We bought a phone and expect it to work. Google should step up and fix every possible bug out there and ofcourse not introduce new ones.

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4th December 2012, 07:05 PM   |  #8  
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Quote:
Originally Posted by mariosraptor

I just finished the forever gone solution. Tbh it is now worst than before.

Did you remount /data with -o discard before using Forever Gone?
4th December 2012, 07:09 PM   |  #9  
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Quote:
Originally Posted by ph4zrd

Did you remount /data with -o discard before using Forever Gone?

Nope. The app did not suggest that.
I will reflash the stock omage again.

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Last edited by mariosraptor; 4th December 2012 at 07:15 PM.
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4th December 2012, 07:47 PM   |  #10  
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Quote:
Originally Posted by mariosraptor

Nope. The app did not suggest that

The app isn't made for fixing this problem. It is made for overwriting free space on the sdcard.
So of course this doesn't fix it. The mount option does and is absolutely essential.
By simply using Forever Gone you only tried how bad this can get

Quote:
Originally Posted by mariosraptor

I will reflash the stock omage again.

This might temporarily help (a wipe of the system, cache and userdata partitions does), at least a little bit.
But it doesn't fix the problem. The phone will slow down again.


Step-by-step guide

1.
Make sure you have a eMMC chip of type V3U00M using this or this app as I mentioned above.
Otherwise it might be possible that the following commands HARD BRICK your phone.
You can also use the following command: cat /sys/class/block/mmcblk0/device/name

2.
Make sure your phone is rooted.

3.
Install and run this app.
This temporarily solves the problem, the phone will eventually begin to slow down again.

Type the following commands in a Terminal or preferably an adb shell:
Code:
su
mount -o remount,discard /data
dd if=/dev/zero of=/data/tmp.bin
rm /data/tmp.bin
It WILL take a long time (up to 3 hours maybe) and your phone might soft-reboot like mine did. Therefore using adb would be better... Some users also reported a speedup when this is done in recovery mode (CWM/TWRP) via adb.
The dd command seems to fail, issuing a message similar to "no space left on device". This is normal as we don't give the command a particular file size so it fills the partition until no space is left on it. (That's what we want to do)
This temporarily solves the problem. After you reboot the remount option is lost and the phone will begin to slow down again.
Btw, you can also use the Forever Gone app instead of the dd/rm commands. So if you don't want to use the command line, apply Step 4 first (using Script Manager), reboot and then run Forever Gone.


4.
To prevent this, add the following code to a script and put it in the init.d folder (if your rom supports it) or use an app like Script Manager to run it on every boot. (Make sure it is started with root privileges!)
Code:
#!/system/bin/sh 
mount -o remount,discard /data
mount -o remount,discard /cache
5.
Profit.

The only phones affected seem to be Galaxy Nexus GSM (i9250) models with the the V3U00M chip for which it is apparently essential to get TRIM/erase/discard commands or whatever for every single block deleted.
The only reported production dates of bad chips are 08/2012, 09/2012 and 10/2012 until now. Maybe chips produced earlier and/or later are also affected.
You can get the production date of you eMMC chip using the following command: cat /sys/class/block/mmcblk0/device/date

Additional information

Google Code Bugreport (already posted above)

Galaxy Nexus Storage Performance Over Time & TRIM
[Q] Why is my Nexus so sluggish?
My Galaxy Nexus is being very laggy...
[Q] Very slow and laggy Nexus
Other guide, some FAQ + patched kernel (for a specific ROM)

LagFix Tool

some eMMC chip types used at the beginning of 2012 (not affected, type VYL00M for GSM Nexus)
Benchmark of this chip on low-mem conditions

Maybe someone can make a flashable zip or something like that for automating this.
If enough people report this problem I might also do it.


I am not responsible for killing little kittens or your girlfriend getting pregnant by that.
Cheers!
Last edited by ph4zrd; 23rd January 2013 at 02:28 PM.

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