# Droid 2 (+D2G&DX?) - SD Card Read_Ahead_KB Question



## PhantomGamers (Sep 27, 2011)

Hey guys, figured I would start a new topic for this.

Basically I want to know why we only change read_ahead_kb in /sys/devices/virtual/bdi/179:0/

I'm looking at scripts for other phones and they also modify all of the other folders' read_ahead_kb in -> /sys/devices/virtual/bdi/

Is there a reason why we SHOULDN'T modify those? Wouldn't it help?
If not the 1:0,7:0,0:7,etc,etc,etc folders what about 179:32?


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## bikedude880 (Jun 18, 2011)

Check out /proc/devices for the numbers that X:Y indicate. 179 is our mmc device.


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## PhantomGamers (Sep 27, 2011)

I see, thanks for that!

But what about these:
/sys/block/mmcblk1/queue/read_ahead_kb
/sys/block/mmcblk1/queue/nr_requests
/sys/block/mmcblk0/queue/nr_requests

On another phone the first one was set to 3072 and the other two to 2048.
/sys/block/mmcblk0/queue/read_ahead_kb was also set to 3072 but on our phones it's already 2048 (unless one of my scripts changes that).
/sys/block/mmcblk1/queue/read_ahead_kb however is 128.


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## bikedude880 (Jun 18, 2011)

Maybe this might be interesting: https://hep.pa.msu.edu/twiki/bin/view/AGLT2/Dell2950KernelTuning


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## PhantomGamers (Sep 27, 2011)

Thanks a lot for your help


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