Compcache - Revision history

imported_>jmo707: /* "Coronary", "diminished user sexual functions" and "watchdog barks" where hilarious, but out of place =)*/

2015-03-11T22:39:16Z

"Coronary", "diminished user sexual functions" and "watchdog barks" where hilarious, but out of place =)

← Older revision		Revision as of 22:39, 11 March 2015
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	====The problem====		====The problem====
	----		----
	Lack of RAM is considered one on the main performance bottlenecks a N900 user has to contend with. In its stock set-up, the N900 is prone to having massive swapping ~~coronary~~ after even short periods of heavy use. This leads to poor performance, ~~diminished user sexual function~~ and in the worst cases, a reboot ~~due to watchdog timers becoming ignored and letting out a panicked bark~~. This is generally alleviated in one or several of four ways.		Lack of RAM is considered one on the main performance bottlenecks a N900 user has to contend with. In its stock set-up, the N900 is prone to having massive swapping after even short periods of heavy use. This leads to poor performance, and in the worst cases, a reboot. This is generally alleviated in one or several of four ways.


	==== The solutions====		==== The solutions====

imported_>raimu: Removed a grocerer's apostrophe

2012-06-16T14:40:20Z

Removed a grocerer's apostrophe

← Older revision		Revision as of 14:40, 16 June 2012
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	Apparently compcache is the single greatest thing to ever happen to the N8x0.		Apparently compcache is the single greatest thing to ever happen to the N8x0.
	<br>		<br>



	=== N900 ===		=== N900 ===
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	====The problem====		====The problem====
	----		----
	Lack of RAM is considered one on the main performance bottlenecks a N900 user has to contend with. In ~~it's~~ stock set up the N900 is prone to having massive ~~swap space~~ coronary. This ~~can~~ leads to poor performance, diminished user sexual function and in the worst cases, a reboot due to watchdog timers becoming ignored and letting out a panicked bark. This is generally alleviated in one or several of four ways.		Lack of RAM is considered one on the main performance bottlenecks a N900 user has to contend with. In its stock set-up, the N900 is prone to having massive swapping coronary after even short periods of heavy use. This leads to poor performance, diminished user sexual function and in the worst cases, a reboot due to watchdog timers becoming ignored and letting out a panicked bark. This is generally alleviated in one or several of four ways.

imported_>raimu: Reworked a bit and added some notes. Hopefully, people agree it's for the better.

2012-06-16T14:36:23Z

Reworked a bit and added some notes. Hopefully, people agree it's for the better.

← Older revision		Revision as of 14:36, 16 June 2012
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	Compcache or Ramzswap, hitherto referred as ramz is a method for taking a chunk of 'normal' ~~ram~~ and using it as a compressed virtual memory(VM) swap space. That is, we use ~~ram~~ as virtual virtual ~~ram~~ by compressing the contents on the fly and storing it in ~~ram~~. This is in order to squeeze as much space from the limited ~~ram~~ as possible.		Compcache or Ramzswap, hitherto referred as ramz is a method for taking a chunk of 'normal' RAM and using it as a compressed virtual memory (VM) swap space. That is, we use RAM as a sort of a virtual, virtual RAM by compressing the contents on the fly and storing it in RAM that's marked up as a swap device. This is in order to squeeze as much space from the limited RAM as possible. A swap device created from compressed RAM is many times faster than a regular swap device using hard drives or traditional flash memory.


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	====The problem====		====The problem====
	----		----
	Lack of ~~ram~~ is ~~seen as~~ one on the main performance bottlenecks an N900 user has to contend with. In it's stock set up the N900 is prone to having massive swap space coronary. This can leads to poor performance, diminished user sexual function and in the worst cases, a reboot due to watchdog timers becoming ignored. This is generally alleviated in 1 of 4 ways.		Lack of RAM is considered one on the main performance bottlenecks a N900 user has to contend with. In it's stock set up the N900 is prone to having massive swap space coronary. This can leads to poor performance, diminished user sexual function and in the worst cases, a reboot due to watchdog timers becoming ignored and letting out a panicked bark. This is generally alleviated in one or several of four ways.


	==== The solutions====		==== The solutions====
	----		----
	=====Install '~~swappolube~~'=====		=====Install 'Swappolube'=====


	[[Swappolube]] is a set of VM tweaks initially ~~dreamed~~ up by the user Hawaii. For MOST users the installation of ~~swappolube~~ from the repositories and applying the default settings will suffice to alleviate the problem.		[[Swappolube]] (sic) is a set of VM parameter tweaks initially dreamt up by the user Hawaii. For MOST users, the installation of Swappolube from the repositories and applying the default settings will suffice to alleviate the problem.


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	It has been found that as the swap space fills up the OS is unable to allocate continuous space on the swap ~~space~~. This leads to poor performance. The package [[ereswap]] was created to ~~alleviate~~ this.		It has been found that as the swap space fills up, the OS is eventually more and more unable to allocate continuous space on the swap device. This leads to poor performance, that can be periodically reset by turning the swapping device off and on again, clearing the slate. The package [[ereswap]] was created to make this easy.


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	The ~~articles~~ namesake. The use of compcache has been a contentious issue. Most users have found it to cause extremely poor system performance. As soon as the ramz space gets ~~filled,~~ which is pretty quick, the system grinds to a slow crawl.		The article's namesake. The use of compcache has been a contentious issue. Most users have found it to cause extremely poor system performance. For many users, as soon as the ramz space gets full - which is pretty quick, considering it's only tens of megabytes large - the system grinds to a slow crawl.

			Some empirical and anecdotal evidence suggests that the 'extreme' swap-retention settings of swappolube (that most users run) are highly unsuitable ramz. Swappolube sets the VM to swap as rarely as possible. This does not work for ramz - likely, an opposite approach must be taken: The device must swap a lot. As in this scenario the swapping is optimally mostly done to the RAM swap device, there will be little penalty in speed.

	It has been suggested that by some users that the 'extreme' settings of swappolube that most users run are utterly wrong for ramz. Swappolube sets the VM to swap little bits rarely. This does not work for ramz. The opposite approach for ramz must be taken, the device must swap a lot, all the time. As the swapping is to ram, there will be little penalty in speed. Although it has been suggested that there will perhaps be a slight penalty in processor use (de/compression of ramz) and thus battery life.

	====Using compcache====		====Using compcache====
	----		----
	<br>		<br>

	'''''Caveats!'''''		'''''Caveats!'''''


	*While ramz does work on kernel power version 49 (KP49) it is highly recommended that you use KP50!		*While ramz does work on kernel power version 49 (KP49), it is highly recommended that you use KP50!

	*Ramz requires a disksize that is specified in KB in powers of 2. Acceptable sizes are:		*Ramz requires a disksize that is specified in KB in powers of 2. Acceptable sizes are:
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	\|65536		\|65536
	\|64MB		\|64MB
			\|-
			\|98304
			\|96MB
	\|-		\|-
	\|131072		\|131072
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	</div>		</div>

	*It is recommended that you use 64MB		*It is recommended that you do not use more than 64MB for ramz.

			*Unless enabled very early in the device boot, you MUST have swap enabled on a physical disk before enabling ramz, or your n900 WILL insta-crash and reboot, potentially corrupting your file system!

			*Due to the CPU load slightly increased by the de/compression done by ramz, using ramz likely incurs a slight penalty in battery life.

	*~~You MUST have swap enabled on a physical disk before enabling ramz or~~ your n900 ~~WILL insta-crash potentially taking~~ your ~~file system with it~~!		''Compcache is still considered experimental! It may not work, asplode your n900 and rip your @!# clean off. You have been warned.''

	''Compcache is still considered experimental! It may not work, assplode your n900 and rip your *** clean off. You have been warned.''

	====How to enable compcache====		====How to enable compcache====
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	</source>		</source>

	Once enabled you must tell the system to use the ramz disk:		It will take a short while for the kernel to catch up with this, so you should pair this with a 'sleep 1' command. Once enabled, you must tell the system to use the ramz disk:

	<source lang="bash">		<source lang="bash">
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	</source>		</source>

	For any of this to be any benefit the ramz disk needs to have a higher priority than the 'physical' swap space. Make sure ALL applications are closed and disable then re-enable your physical swap. On a stock setup (swap on eMMC) you can do this:		For any of this to be any benefit, the ramz disk needs to have a higher priority than the 'physical' swap space. Make sure ALL applications are closed and disable then re-enable your physical swap. On a stock setup (swap on eMMC) you can do this:

	<source lang="bash">		<source lang="bash">
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	</source>		</source>

	For other setups i.e. when you have swap on uSD you must substitute 'mmcblk0p3' with the location of your swap space. (If ~~you~~ swap partition is the second partition on the uSD then it will be 'mmcblk1p2').		For other setups, i.e. when you have swap on uSD you must substitute 'mmcblk0p3' with the location of your swap space. (If your swap partition is the second partition on the uSD then it will be 'mmcblk1p2').

	You can now check you have the appropriate partitions with:		You can now check you have the appropriate partitions with:
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	You can see ramzswap is 64MB AND with a higher priority than mmcblk0p3.		You can see ramzswap is 64MB AND with a higher priority than mmcblk0p3.

	Now you must change ~~you~~ VM settings to ~~effectivly~~ use the new ramz setup. The following settings have been found to work with 32MB, 64MB and 128MB ramz sizes. They are a work in progress and will be updated as they are tuned to the authors workload (heavy user, treating n900 as a pocket laptop as oppose to merely a phone).		Now you must change your VM settings to effectively use the new ramz setup. The following settings have been found to work with 32MB, 64MB and 128MB (beware!) ramz sizes. They are a work-in-progress and will be updated as they are tuned to the authors' workload (heavy user, treating n900 as a pocket laptop as oppose d to merely a phone).

	Paste the below lines into xterm to setup the VM and tune the flash ~~disc~~		Paste the below lines into xterm to setup the VM and tune the flash device usage:

	<source lang="bash">		<source lang="bash">
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	</source>		</source>

	====~~Making~~ all this ~~happen automatically~~====		====Automating all of this====
	----		----

	There is a package called swapset[http://maemo.org/packages/view/swapset/], ~~it claims~~ to setup swaps and the ramz module automatically. The author of this article has not used it and thus cannot vouch for ~~it's~~ effectiveness. Using swapset AND putting the above settings into swappolube would probably cause all of the above to work automatically.		There is a package called swapset[http://maemo.org/packages/view/swapset/], which attempts to setup swaps and the ramz module automatically. The author of this article has not used it, and thus cannot vouch for its effectiveness. Using swapset AND putting the above settings into swappolube would probably cause all of the above to work automatically. Probably.

	<br>		<br>

imported_>vee: /* How to do this all at once */

2012-06-01T11:39:54Z

How to do this all at once

← Older revision		Revision as of 11:39, 1 June 2012
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	#referance: http://www.westnet.com/~gsmith/content/linux-pdflush.htm		#referance: http://www.westnet.com/~gsmith/content/linux-pdflush.htm

	#swapoff ramzswap and ~~remove ramzswap module~~		#Smart swap on/off
	~~swapoff~~ /~~dev~~/~~ramzswap0~~ && sleep 1		#drivelist=$(sfdisk -lnd /dev/mmcblk1)
	~~rmmod~~ /~~ramzswap && sleep~~ 1		if [ "$(cat /proc/swaps \| awk '/mmcblk/ {print $1}' \| cut -d "k" -f2 \| cut -c1)" == "0" ]; then
			echo "swap is on emmc"
			if [ "$(sfdisk -lnd /dev/mmcblk0 \| grep Id=82 \| awk '/mmcblk0/ {print $1}')" ]; then
			nice -20 swapoff $(sfdisk -lnd /dev/mmcblk0 \| grep Id=82 \| awk '/mmcblk0/ {print $1}')
			#insert ramzswap module and specify disksize
			insmod /lib/modules/current/ramzswap.ko disksize_kb=65536 && sleep 1
			nice -20 swapon $(sfdisk -lnd /dev/mmcblk0 \| grep Id=82 \| awk '/mmcblk0/ {print $1}')
			echo "swap is on swapped on emmc"
			fi
			fi

	#insert ramzswap module and specify disksize		if [ $(cat /proc/swaps \| awk '/mmcblk/ {print $1}' \| cut -d "k" -f2 \| cut -c1) = "1" ]; then
	insmod /lib/modules/current/ramzswap.ko disksize_kb=65536 && sleep 1		nice -20 swapoff $(sfdisk -lnd /dev/mmcblk1 \| grep Id=82 \| awk '/mmcblk1/ {print $1}')
			#insert ramzswap module and specify disksize
	#swapon ~~ramzswap & swap~~-~~reset eMMC~~		insmod /lib/modules/current/ramzswap.ko disksize_kb=65536 && sleep 1
	~~swapon~~ /dev/~~ramzswap0 && sleep 1~~		nice -20 swapon $(sfdisk -lnd /dev/mmcblk1 \| grep Id=82 \| awk '/mmcblk1/ {print $1}')
	~~swapoff~~ /~~dev~~/~~mmcblk0p3 && sleep 1 && swapon /dev/mmcblk0p3 && sleep~~ 1		echo "swap is on sd"
			fi

	#vm changes		#vm changes

imported_>vee: /* How to do this all at once */

2012-06-01T09:18:13Z

How to do this all at once

← Older revision		Revision as of 09:18, 1 June 2012
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	echo 32 > /sys/block/mmcblk0/queue/iosched/quantum		echo 32 > /sys/block/mmcblk0/queue/iosched/quantum
	echo 32 > /sys/block/mmcblk1/queue/iosched/quantum		echo 32 > /sys/block/mmcblk1/queue/iosched/quantum
	echo ~~125~~ > /sys/block/mmcblk0/queue/iosched/fifo_expire_sync		echo 100 > /sys/block/mmcblk0/queue/iosched/fifo_expire_sync
	echo ~~125~~ > /sys/block/mmcblk1/queue/iosched/fifo_expire_sync		echo 100 > /sys/block/mmcblk1/queue/iosched/fifo_expire_sync
	echo ~~250~~ > /sys/block/mmcblk0/queue/iosched/fifo_expire_async		echo 200 > /sys/block/mmcblk0/queue/iosched/fifo_expire_async
	echo ~~250~~ > /sys/block/mmcblk1/queue/iosched/fifo_expire_async		echo 200 > /sys/block/mmcblk1/queue/iosched/fifo_expire_async

	#display results		#display results

imported_>vee: /* How to enable compcache */

2012-06-01T09:17:56Z

How to enable compcache

← Older revision		Revision as of 09:17, 1 June 2012
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	Now you must change you VM settings to effectivly use the new ramz setup. The following settings have been found to work with 32MB, 64MB and 128MB ramz sizes. They are a work in progress and will be updated as they are tuned to the authors workload (heavy user, treating n900 as a pocket laptop as oppose to merely a phone).		Now you must change you VM settings to effectivly use the new ramz setup. The following settings have been found to work with 32MB, 64MB and 128MB ramz sizes. They are a work in progress and will be updated as they are tuned to the authors workload (heavy user, treating n900 as a pocket laptop as oppose to merely a phone).

			Paste the below lines into xterm to setup the VM and tune the flash disc

	<source lang="bash">		<source lang="bash">
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	echo 32 > /sys/block/mmcblk0/queue/iosched/quantum		echo 32 > /sys/block/mmcblk0/queue/iosched/quantum
	echo 32 > /sys/block/mmcblk1/queue/iosched/quantum		echo 32 > /sys/block/mmcblk1/queue/iosched/quantum
	echo ~~125~~ > /sys/block/mmcblk0/queue/iosched/fifo_expire_sync		echo 100 > /sys/block/mmcblk0/queue/iosched/fifo_expire_sync
	echo ~~125~~ > /sys/block/mmcblk1/queue/iosched/fifo_expire_sync		echo 100 > /sys/block/mmcblk1/queue/iosched/fifo_expire_sync
	echo ~~250~~ > /sys/block/mmcblk0/queue/iosched/fifo_expire_async		echo 200 > /sys/block/mmcblk0/queue/iosched/fifo_expire_async
	echo ~~250~~ > /sys/block/mmcblk1/queue/iosched/fifo_expire_async		echo 200 > /sys/block/mmcblk1/queue/iosched/fifo_expire_async
	</source>		</source>

imported_>vee: /* How to enable compcache */

2012-06-01T09:16:30Z

How to enable compcache

← Older revision		Revision as of 09:16, 1 June 2012
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	<source lang="bash">		<source lang="bash">
	echo 3 > /proc/sys/vm/dirty_ratio		echo 10 > /proc/sys/vm/dirty_ratio
	echo 3 > /proc/sys/vm/dirty_background_ratio		echo 10 > /proc/sys/vm/dirty_background_ratio
	echo ~~100~~ > /proc/sys/vm/dirty_writeback_centisecs		echo 250 > /proc/sys/vm/dirty_writeback_centisecs
	echo ~~100~~ > /proc/sys/vm/dirty_expire_centisecs		echo 1000 > /proc/sys/vm/dirty_expire_centisecs
	echo ~~32 > /proc/sys/vm/min_free_kbytes~~		echo 100 > /proc/sys/vm/swappiness
	~~echo 95~~ > /proc/sys/vm/swappiness
	echo 200 > /proc/sys/vm/vfs_cache_pressure		echo 200 > /proc/sys/vm/vfs_cache_pressure
	echo 0 > /proc/sys/vm/page-cluster		echo 0 > /proc/sys/vm/page-cluster
	echo 4 > /sys/block/mmcblk0/queue/nr_requests		echo 64 > /sys/block/mmcblk0/queue/nr_requests
	echo 4 > /sys/block/mmcblk1/queue/nr_requests		echo 64 > /sys/block/mmcblk1/queue/nr_requests
			echo 0 > /sys/block/mmcblk0/queue/iosched/slice_idle
			echo 0 > /sys/block/mmcblk1/queue/iosched/slice_idle
			echo 32 > /sys/block/mmcblk0/queue/iosched/quantum
			echo 32 > /sys/block/mmcblk1/queue/iosched/quantum
			echo 125 > /sys/block/mmcblk0/queue/iosched/fifo_expire_sync
			echo 125 > /sys/block/mmcblk1/queue/iosched/fifo_expire_sync
			echo 250 > /sys/block/mmcblk0/queue/iosched/fifo_expire_async
			echo 250 > /sys/block/mmcblk1/queue/iosched/fifo_expire_async
	</source>		</source>

imported_>vee: /* How to do this all at once */

2012-06-01T09:14:39Z

How to do this all at once

@@ Line 145: / Line 145: @@
 <source lang="bash">
 insmod /lib/modules/current/ramzswap.ko disksize_kb=65536 && sleep 1
 swapon /dev/ramzswap0 && sleep 1
 swapoff /dev/mmcblk0p3 && sleep 1 && swapon /dev/mmcblk0p3 && sleep 1
-echo 3 > /proc/sys/vm/dirty_ratio
-echo 3 > /proc/sys/vm/dirty_background_ratio
+#vm changes
-echo 100 > /proc/sys/vm/dirty_writeback_centisecs
+#/proc/sys/vm/dirty_ratio (default 40)
-echo 100 > /proc/sys/vm/dirty_expire_centisecs
+echo 10 > /proc/sys/vm/dirty_ratio
-echo 32 > /proc/sys/vm/min_free_kbytes
-echo 95 > /proc/sys/vm/swappiness
+#dirty_background_ratio
-echo 200 > /proc/sys/vm/vfs_cache_pressure
+echo 10 > /proc/sys/vm/dirty_background_ratio
 echo 0 > /proc/sys/vm/page-cluster
 ====Making all this happen automatically====

imported_>vee: /* Using compcache */

2012-05-28T12:33:50Z

Using compcache

← Older revision		Revision as of 12:33, 28 May 2012
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	*You MUST have swap enabled on a physical disk before enabling ramz or your n900 WILL insta-crash potentially taking your file system with it!		*You MUST have swap enabled on a physical disk before enabling ramz or your n900 WILL insta-crash potentially taking your file system with it!

	''Compcache is still considered experimental! It may not work, assplode your n900, rip ~~you~~ *** clean off. You have been warned.''		''Compcache is still considered experimental! It may not work, assplode your n900 and rip your *** clean off. You have been warned.''

	====How to enable compcache====		====How to enable compcache====

imported_>vee: /* N8x0 */

2012-05-28T11:08:53Z

N8x0

← Older revision		Revision as of 11:08, 28 May 2012
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	To be added by a wild N8x0 user...		To be added by a wild N8x0 user...
	<br>		<br>
			Apparently compcache is the single greatest thing to ever happen to the N8x0.
	<br>		<br>