[MOD] Tweaks for SD card performance

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Here is a thread that seems to be making the rounds throughout the forums...

http://forum.xda-developers.com/show....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...

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/show....php?t=1008612

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

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...

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

Originally Posted by Jaostar

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.

Originally Posted by dalingrin

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...

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.

I'm only setting it to 1024k. I feel like that is plenty high.

Originally Posted by dalingrin

I'm only setting it to 1024k. I feel like that is plenty high.

Yes 1024 is what I'm running really gave the best all around performance.

I think I found the internal memory and it's set to 128 by default

can't find any real difference between 64 and 4096. That looks like the only other mmc device though, so it must be it.

Originally Posted by chisleu

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...