[MOD] Tweaks for SD card performance

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Vermithrax

Senior Member
Feb 6, 2009
111
4
Mobile, AL
Here is a thread that seems to be making the rounds throughout the forums...

http://forum.xda-developers.com/showthread.php?t=1010807

Following the guidelines in the thread, here are my results with CM7 using a Kingston 8GB Class 6 card...

Before:
Write - 6.6 MB/s
Read - 15.2 MB/s

After:
Write - 5.8 MB/s
Read - 94.4 MB/s

I would recommend playing with the values to see what works best for your particular SD card... Not quite sure
if it is a placebo type effect, but apps like the Gallery and games that use the SD card are noticeably faster...

Have fun...
 

chisleu

Senior Member
Mar 7, 2011
1,042
105
Myrtle Beach SC
I did extensive testing on a patriot class 10 8gb card today.

I had lowest standard deviation on results using 1024 buffer. I also had the highest reads at that buffer with a higher write speed.

I had the highest write speed at 4096, but the read speeds were slower than 1024.

I rebooted several times to make sure that wasn't playing into it, and reran many test. All results were relatively consistent.

~11.6 write
~86 read
@1024

~11.9 write
~79.4 read
@4096

~10.8 write
~71.9 read
@128

The change wasn't huge for me. Most have reported 2048 as the best setting.

Also, I updated my cm7_mod to include this. Working on making it installable w/ the scripting...
http://forum.xda-developers.com/showthread.php?t=1008612

It's only meant to be used with cm7_tablet_tweaks as a base now.
 

Jaostar

Member
Nov 19, 2007
24
3
Couldn't such a buffer size setting be usefull for emmc (internal memory) too ?

I'm using dalingrin's OC kernel with the IO issue, and it feels slower than my SD card...
 

dalingrin

Inactive Recognized Developer
Nov 6, 2007
1,433
2,756
I've commited this tweak already today. I would be interested to find the optimal value for mmcblk0.

Couldn't such a buffer size setting be usefull for emmc (internal memory) too ?

I'm using dalingrin's OC kernel with the IO issue, and it feels slower than my SD card...

My current kernel should not have any IO issues.
 
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chisleu

Senior Member
Mar 7, 2011
1,042
105
Myrtle Beach SC
I've commited this tweak already today. I would be interested to find the optimal value for mmcblk0.



My current kernel should not have any IO issues.

Instructions for tweaking the emmc are in that thread. I wouldn't mind taking the time to test and crunch the numbers but sd tools only wants to test my SD card.

EDIT:

App called J Disk Benchmark 2.0 can test internal memory. Working on testing now.

Uhm... my SD card tests faster...
 
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knaries2000

Senior Member
Apr 13, 2009
172
12
I hope people don't go over board and incorporate this type of permformance increases in their roms by default based on bench mark tools. there is value in increasing readahead for some access patterns, mainly when doing lots of sequencial reads. the trade off of course is at the expense of memory usage. nook even with its 500mb of memory is still not considered high in memory. setting the readahead to 2mb is quite aggressive and will work well in some work loads like galary when reading lots of files around 2mb in size while in other work loads it may actually have negative affects. I am not saying that this specific tweak is bad because I haven't done any tests myself, but don't always believe the numbers u see from benchmark tools.
 
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Jaostar

Member
Nov 19, 2007
24
3
App called J Disk Benchmark 2.0 can test internal memory. Working on testing now.

Uhm... my SD card tests faster...

Yep, it's the same for me, my Class 6 SD card achieves 6,3/11,6 and the internal memory only 4,86/7,52...

BTW :
J Disk Benchmark 2.0 doesn't use the cache, so this tweak wont affect the results...
 
Last edited:

chisleu

Senior Member
Mar 7, 2011
1,042
105
Myrtle Beach SC
OK, I can't get any meaningful numbers anymore. I think yesterday's test was a fluke. I can't get any real changes from 128 to 4096 (or in between) with fast or slow SD cards, big or small, black or dark black.

The write speed on slower cards is lower (5-6mb/s) and the faster cards are higher (10-12MB/s) and read speed for all is 80-90mb/s.

Maybe this is a performance mod not for us?
 

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    I've commited this tweak already today. I would be interested to find the optimal value for mmcblk0.

    Couldn't such a buffer size setting be usefull for emmc (internal memory) too ?

    I'm using dalingrin's OC kernel with the IO issue, and it feels slower than my SD card...

    My current kernel should not have any IO issues.
    1
    I hope people don't go over board and incorporate this type of permformance increases in their roms by default based on bench mark tools. there is value in increasing readahead for some access patterns, mainly when doing lots of sequencial reads. the trade off of course is at the expense of memory usage. nook even with its 500mb of memory is still not considered high in memory. setting the readahead to 2mb is quite aggressive and will work well in some work loads like galary when reading lots of files around 2mb in size while in other work loads it may actually have negative affects. I am not saying that this specific tweak is bad because I haven't done any tests myself, but don't always believe the numbers u see from benchmark tools.