Kernel Optimizations - Galaxy S II Q&A, Help & Troubleshooting

If anyone is compiling a kernel, please unset CONFIG_UEVENT_HELPER_PATH.
It is currently set to /sbin/hotplug, which does not exist.
You might also set
echo 5 > /proc/sys/vm/laptop_mode
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
somewhere in the initramfs.

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What does these settings do?

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lynx2k50 said:
What does these settings do?
Click to expand...
Click to collapse
if CONFIG_UEVENT_HELPER_PATH is set, then the kernel tries to execute that helper tool every time a hotplug event occurs. Unsetting it would save a lot of forks at boot time.
Code:
echo 5 > /proc/sys/vm/laptop_mode
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
These settings delay the disk writeback, so the disk device has to wake up less often (given it goes into sleep mode ).

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Ah okay so i can expect better battery life (more sleep time) and a faster booting.
Well done, thanks.
I hope some devs are going to integreate it.

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OK good point to try.
Added now on my Cognition 1.07
Code:
bash-4.1# cat /etc/init.d/90laptop.sh
#!/system/bin/sh
echo 5 > /proc/sys/vm/laptop_mode
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs

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Code:
diff --git a/arch/arm/configs/c1_rev02_defconfig b/arch/arm/configs/c1_rev02_defconfig
index a7992c0..ccd06df 100644
--- a/arch/arm/configs/c1_rev02_defconfig
+++ b/arch/arm/configs/c1_rev02_defconfig
@@ -917,7 +917,7 @@ CONFIG_RFKILL_INPUT=y
#
# Generic Driver Options
#
-CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
+CONFIG_UEVENT_HELPER_PATH=""
# CONFIG_DEVTMPFS is not set
CONFIG_STANDALONE=y
CONFIG_PREVENT_FIRMWARE_BUILD=y

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Can someone pls create a update.zip or else for the cognition rom?
Or a shirt instruction.
Sry for my englisch
from my SGS running MIUI 2.3.4

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If you have the CF-Root kernel installed, you can just place this in /data/local/customboot.sh
Code:
echo 5 > /proc/sys/vm/laptop_mode
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
echo -e '\000\000\000' > /proc/sys/kernel/hotplug

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saturn_de said:
If you have the CF-Root kernel installed, you can just place this in /data/local/customboot.sh
Code:
echo 5 > /proc/sys/vm/laptop_mode
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
echo -e '\000\000\000' > /proc/sys/kernel/hotplug
Click to expand...
Click to collapse
the first two might help. (does Solid State internal storage need "sleep" mode?)
but depending on when the custom script is run the last line may be useless here..

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Does it only work with a CF-Kernel, i've tagraks kernel, and cant find any file in data/locel .
Greetz

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saturn_de said:
These settings delay the disk writeback, so the disk device has to wake up less often (given it goes into sleep mode ).
Click to expand...
Click to collapse
It doesn't go into sleep mode since it's not a spinning disk.
(Or you could look at it as always being in sleep mode when not in use - there's no spindown/spinup phase.)
So you're not gonna see any battery benefits from that.

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Added into my installation on my handset. No way to test it whether it will increase stabilty nor speed, but it does tidy thinngs up.