maemo.org - Talk - Using Micro SD Card as Virtual Ram on Nokia N900?

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- Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)

- - Using Micro SD Card as Virtual Ram on Nokia N900? (https://talk.maemo.org/showthread.php?t=42357)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Thanks Whitewolf that looks alot safer. What do you get for the swap priorities when you cat /proc/swaps ?

As I am personally going to stick to running a script manually after a reboot, and following Whitewolfs lead using sfdisk, I have added the lines below to my tuning script to ensure the uSD swap is available before making any changes.

Code:

testmicro="/dev/mmcblk1p2"

swapmicro=$(sfdisk -l /dev/mmcblk1 | grep /dev/mmcblk1p2 | awk '/mmcblk1p2/ {print $1}')

     if [ "$testmicro" == "$swapmicro" ]; then

       swapon /dev/mmcblk1p2

       swapoff /dev/mmcblk0p3

       swapon /dev/mmcblk0p3

     else

       echo "Cannot find swap parition on uSD card, swap still on internal memory"

     fi

You could of course run this at startup, and if the swap partition on the removable memory is not available, things will stay as standard. If the swap on the card is available then both partitions will be used, with the faster memory (assuming it is faster, I'm using a class6) being utilised primarily.

I have tested this by running with no SD card, and it works; if mmcblk1p2 is not present it will make no swap changes.

I'd like to be able to get this added to the wiki page, as the current instructions only sets up the faster swap as secondary- and it will never get used considering the huge default primary swap. As I've said I'm kinda new to all this so I wouldn't dream of doing so unless somebody with some experience had a look at the above code and gave me some feedback.

Does it look safe enough to add to the wiki?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Cat /proc/swaps
/dev/mmcblk0p3 Priorit=-1
/dev/mmcblk1p3 Priorit=-2

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I like but I see a limitation because you say what the swap.

I watch as it automatically adapt to the example that I put myself and not depend on the human well.

How to place her at the start to run?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Here's a startup script I made (goes in /etc/events.d/) based on elipsoid's script to check for the microSD swap file before changing the swap configuration. I broke some of the commands into two lines because depending on how you partitioned your MicroSD, you might get un-suppressable warning messages from sfdisk that would mess up the process.

Code:

start on started hildon-desktop

stop on starting shutdown

console none

service



script



drivelist=$(sfdisk -lnq /dev/mmcblk1)

swapmicro=$(echo "$drivelist" -n | grep swap | awk '/mmcblk1p2/ {print $1}')

if [ "$swapmicro" ]; then

    swapon $swapmicro

    swapoff /dev/mmcblk0p3

    swapon /dev/mmcblk0p3

fi



end script

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

With the code as you wrote it I do not ever ride swap the SD.

I would remove the following line:

Code:

testmicro = "/ dev/mmcblk1p2"

Modify the line ...

Code:

swapmicro = $ (echo "$ drivelist"-n | grep / dev/mmcblk1p2 | awk '/ mmcblk1p2 / {print $ 1}')

For these other ...

Code:

drivelist = $ (sfdisk -ln /dev/mmcblk1 | grep swap)

swapmicro = $ (echo "$ drivelist"-n | awk ' /mmcblk1p/ {print $ 1}')

Show only that partition is a swap rate, regardless of the number of partition.

Then modify the following lines ...

Code:

if [ "$ testmicro" == "$ swapmicro" ]; then

    swapon / dev/mmcblk1p2

    swapoff / dev/mmcblk0p3

    swapon / dev/mmcblk0p3

For these, that would trigger the swap of the card as your indicastes:

Code:

if [ $ swapmicro ]; then

    swapon $ swapmicro

    swapoff /dev/mmcblk0p3

    swapon /dev/mmcblk0p3

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

My script worked fine but I'm going to incorporate your improvements into my earlier post (with one little change to deal with sfdisk's warning messages)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I look forward to this script! Good idea.

.. If I can help, I will love it.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Good stuff guys, this is looking very polished and robust - certanly a smarter way of doing things and nice and compact.

Gameboy, the -q switch for sfdisk surpresses warning messages, I've just tried it and it works.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I tested with the amendment proposed and returns nothing if there are error messages by sfdisk.

I confirm that the "-q" sfdisk output prevents error messages.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Actually I tried the -q and it didn't work for me (Gives a long warning about paritition table cylinders), but it couldn't hurt to add it to the script, will do.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Sorry your right the -q does nothing (warnings scrolled past top of screen on N900, was doing things remotely till now).

What does work is if you use the switch for msdos mode, -d, it returns a similar list except that now now the linux swap is listed as Id=82, so we can use this instead.

Code:

start on started hildon-desktop

stop on starting shutdown

console none

service



script



drivelist=$(sfdisk -lnd /dev/mmcblk1)

swapmicro=$(echo "$drivelist" -n | grep Id=82 | awk '/mmcblk1/ {print $1}')

if [ "$swapmicro" ]; then

    swapon $swapmicro

    swapoff /dev/mmcblk0p3

    swapon /dev/mmcblk0p3

fi



end script

That works cleanly for me with no warning messages, though I have only ran it in a test script where I echo "$swapmicro" and it returns:
/dev/mmcblk1p2

I have also changed the awk part, so that instead of looking for the specific swap partition /mmcblk1p2/, it looks for the more general swap on /mmcblk1/.
I think this is what Whitewolf was suggesting in case people have their cards partitioned differently.
I think thats it now - ready to go?
:)
EDIT: I have tested this now by adding to /etc/event.d/ and it works as expected. On reboot with no card present no swap changes are made. With swap on SD present it enables swap with the faster memory having a higher priority.

If you are going to do this I'd suggest putting it in file on its own - or if you are adding this to an existing tuning script, put it at the end as it will exit when no external swap is detected.
(Many thanks GameboyRMH and Whitewolf, this noob has learned a lot working on this with you)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Great stuff.. Might do this later on when I'm ready. :)

Thanks

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I love, has been very clean script.

I will try.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Finally I think what we need for N900 is a 512 Mb RAM chip behind a SD controler with microSD format.
For swap only, there is no need of persistence as it remains on voltage.

Question: what is the best way to benchmark N900 and collect perf stats, specifically about swap usage ?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I set up a 768 MB swap partition on p3 of my class 6 MicroSD using gparted on my laptop.

I set up two Queen BeeCON widgets:
Widget one:
Command Name: MicroSD Swap On
Command: sudo swapon /dev/mmcblk1p3 && sudo swapoff /dev/mmcblk0p3

Widget two:
Command Name: MicroSD Swap On
Command: sudo swapon /dev/mmcblk0p3 && sudo swapoff /dev/mmcblk1p3

I seem to get much better easydebian performance with this (I also installed easy debian to a 6GB ext3 partition to increase performance and app space). It's nice to be able to switch it off, If I want to remove the microsd for whatever reason. I've noticed performance gains using optified programs as well as in easy debian, presumably due to having swap on a seperate disk.

It takes a while for swapoff to run. To monitor progress, I watch it in conky. Once the total swap size gets back down to 768, it's done.

I'm sure there's a much better way to do this, but this was very easy and convenient. This is somewhat unsafe, as it doesn't check to make sure mmcblk1p3 is actually present. If mmcblk1p3 is not present, and you have more memory used in swap than you have free RAM, it will be ugly.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Hello!

I'm not too familiar with Linux yet but I'd like to try to enlarge the capacity of swap memory and learn more. I have read couple Threads here about this issue and I just like to know which of these solutions posted here are the latest and safest? So if someone could reply here or send me a private message which contains the necessary commands in a compressed form. Or is the wiki for that already telling it in that way (so there isn't something else I should do or know)

Thank you :)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

The easiest and safest solution is to first put this script in /etc/event.d:

Code:

start on started hildon-desktop

stop on starting shutdown

console none

service



script



drivelist=$(sfdisk -lnd /dev/mmcblk1)

swapmicro=$(echo "$drivelist" -n | grep Id=82 | awk '/mmcblk1/ {print $1}')

if [ "$swapmicro" ]; then

    swapon $swapmicro

    swapoff /dev/mmcblk0p3

    swapon /dev/mmcblk0p3

fi



end script

Then backup your MicroSD card, and reformat it (Gparted is a good graphical tool to use) with the FAT32 partition as the first partition, and the linux swap partition as the second (whatever size you choose, 384 or 768MB are good sizes). Then put your data back.

And that's it. Totally safe and easy.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Welcome Misferatu.
As gameboy says above it's as simple as correctly formating your SD and running that script at startup (which it will do automatically when you save it to /etc/event.d ) .
I'd say 384mb is a good bet, as I personally haven't ever seen the swap spill over that, the default 786mb swap the n900 originally came with is massive overkill - and remember that original swap will still be available if you do manage to fill the swap you created on the SD card.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

hii frnds .
i want to ask that if we overclock our device to 1Ghz.
then will it give better performance with the swapable virtual memory?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

A 1GHz overclock would give a bigger overall performance boost than running the primary swap from a Class 6 MicroSD, but both modifications at the same time would be best.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I can confirm that this mod can tune-up the device. In fact it must be a great imrpovement because when doing filesharing eMMC s***s. I think it has to do with 2 interfaces. And about speed increase one cannot expect a wonder an increase in 6% - 30% is not bad compared to a shareholde value of an enterprise or other badly coded programs here. BTW. I have some tune-up utilities in my signature.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

osomee is we need high class memory card like class 6 or class 2 is sufficent

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I was looking around for a sandisk extreme and couldnt find one in microSD format, so I grabbed a 4gb Patriot class 10, and put it through a sandra benchmark:

Code:



Benchmark Results

Device Score : 256.2IOPS

Endurance Factor : 49.10

Results Interpretation : Higher scores are better.



Performance vs. Speed

Drive Score : 12.01IOPM/Mbps

Results Interpretation : Higher scores are better.



4kB Files Test

Read Performance : 610.3IOPS / 2.38MB/s

Write Performance : 28.4IOPS / 113.62kB/s

Delete Performance : 48.7IOPS

File Fragments : 1.0

Combined Score : 406.6IOPS / 1.59MB/s



64kB Files Test

Read Performance : 234.4IOPS / 14.65MB/s

Write Performance : 34.8IOPS / 2.18MB/s

Delete Performance : 50.6IOPS

File Fragments : 1.0

Combined Score : 164.5IOPS / 10.28MB/s



1MB Files Test

Read Performance : 18.0IOPS / 18MB/s

Write Performance : 10.5IOPS / 10.54MB/s

Delete Performance : 53.4IOPS

File Fragments : 1.0

Combined Score : 15.4IOPS / 15.38MB/s



16MB Files Test

Read Performance : 1.1IOPS / 18.4MB/s

Write Performance : 0.8IOPS / 12.32MB/s

Delete Performance : 39.7IOPS

File Fragments : 1.0

Combined Score : 1.0IOPS / 16.27MB/s



256MB Files Test

Read Performance : 0.1IOPS / 18.42MB/s

Write Performance : 0.1IOPS / 13MB/s

Delete Performance : 4.0IOPS

File Fragments : 1.0

Combined Score : 0.1IOPS / 16.53MB/s



Performance Test Status

Result ID : Generic STORAGE DEVICE 4GB (RAID/USB)

Platform Compliance : x64

System Timer : 3.58MHz



Endurance Test Status

Operating System Disk Cache Used : No

Use Overlapped I/O : No

Test File Size : 32MB

Block Size : 4kB

File Fragments : 1



Endurance Benchmark Breakdown

Repeated Sector ReWrite : 1MB/s

Sequential Sector Write : 1MB/s

Random Sector Write : 14kB/s



Drive

Total Size : 3.72GB

Free Space : 3.72GB, 100%

Cluster Size : 32kB

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

113 kbyte/s... Best I've seen so far...

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Swap

Swap is a virtual memory which runs off storage devices (HDD, SSD, eMMC, microSD...). It is in a form of a file on a drive (currently this method does not work on Maemo 5) or as a seperate partition (this is actually a better method). Its advantages are that it expands available memory, but it is of course very slow compared to thousand times faster RAM and is therefore used by the system to drop off data which is currently not needed. That means that you can run many programs at once, but they will be running slowly. Virtually every desktop OS does that (for example Windows has page file).

Enabling additional swap is not needed on the N900 for expanding available memory, because it has already 256 MB of RAM and 768 MB of swap space on internal 32 GB eMMC module, resulting in 1 GB of total available memory, which is enough for a device like that. It does however help to offload the work from internal eMMC if there is additional swap space enabled on microSD, because kernel uses both swap partitions and is therefore swapping bandwidth increased which results in higher performance.

Swappiness

Swappiness is a kernel parameter which tells it how aggressively to swap. The more aggressive it is, more RAM is freed, but there is a performance impact, because more data needs to be swapped (written to the slower drive). Swappiness value is between 0 and 100 with 100 being the least aggressive. Maemo 4 had swappiness set to 1 by default while Maemo 5 sets it to 100. The best value is somewhere in between. 256 MB of N900's RAM is enough for a few open programs and there is also enhanced battery life because eMMC doesn't need to write so much swap data. So swappiness should be set somewhere between 30 and 50. It is set with the following command which has to be run as root.

Code:

echo 30 > /proc/sys/vm/swappiness

You can set swappiness at each boot automatically by using a startup script.

(EDIT by egoshin):

In case of N900 you should check that with lower swappiness values you still have an acceptable time of answering calls by phone application. With lower swappiness your N900 more likely meet the situation then there is no enough memory to load phone application for incoming calls - kernel needs to swap-out some applications and you may miss a call. Maximum swap-out speed is around 18 MBytes/sec into eMMC.

With maximum swappiness the kernel just discards the memory pages of some applications because it is already in swap space and cut a time. I believe it is a reason why Nokia set 100 by default for swappiness.

(EDIT by eero):

The situation will also change after a while because swap becomes fragmented (parts of processes' memory are spread all over swap in little pieces). I.e. testing the speed only for few hours after boot isn't enough, new setting needs to be tested for several days.

Configure microSD card for swapping

The microSD card must be split into at least 2 partitions. The first one should be FAT32 (vfat) formatted and the second one must be formatted for linux swap (type 82) and about 384 MB in size. You can change the size of it, but this value should be suitable for most people.

You can repartition and reformat the card with standard Linux tools from the N900 terminal, but the easiest way is to connect the device in mass storage mode to a Linux machine (which can also be a virtual machine if you use other OS as your primary one) and you can do the partitioning with GUI tools.

Using microSD partition as swap

Reboot after the repartitioning and after the boot, this is seen in /dev.

Please Take Note On Below Explaination, This I don't Want You All Simply KeyIn Script Without Understanding What It Means
by
- mmcblk0
- mmcblk0p1
- mmcblk0p2
- mmcblk0p3
- mmcblk1
- mmcblk1p1
- mmcblk1p2

Quote:

* /dev/mmcblk0 (internal eMMC itself)
* /dev/mmcblk0p1 (27 GB partition mounted on /home/user/MyDocs)
* /dev/mmcblk0p2 (2 GB partition mounted on /home)
* /dev/mmcblk0p3 (768 MB swap partition on eMMC)
* /dev/mmcblk1 (microSD itself)
* /dev/mmcblk1p1 (FAT32 partition on your microSD mounted on /media/mmc1)
* /dev/mmcblk1p2 (swap partition on your microSD)

Quote:

1. mmc part defines type of storage device
2. blkX defines number of storage device (0 is internal eMMC, 1 is microSD)
3. pY defines partition number

The swap partitions are not activated, but you can enable swapping on microSD partition with:

Code:

swapon /dev/mmcblk1p2

If you have repartitioned microSD differently you have to change the partition number accordingly. The last part is setting the swapon command to run at every boot and you can do that with a startup script.

There is an additional warning and that is that while the device is running and swap is turned on on microSD partition, you shouldn't take the card out. It would be the same as taking out a RAM stick while running.

Swap priorities

In order to utilize both swap partitions to balance the I/O load (striping), they should have the same priority. The /bin/swapon command shipped with Maemo is the busybox version that does not support -p option. If you don't have Easy Debian environment installed, download the stock Debian mount package for the armel architecture and extract (-x) the swapon binary from it, and copy it somewhere e.g. /sbin/swapon.debian.

It seems that it's not possible to use -p -1 to match the priority of the default eMMC swap partition. I use the following trick:

Code:

1. activate the microSD swap: 

swapon.debian -p 0 /dev/mmcblk1p2



2. temporarily deactivate the eMMC swap: 

swapoff /dev/mmcblk0p3



3. activate it again with matching priority: 

swapon.debian -p 0 /dev/mmcblk0p3

After that your swaps should look like this:

Code:

/home/user # cat /proc/swaps

Result:

Code:

Filename         Type         Size     Used     Priority

/dev/mmcblk0p3   partition    786424   65464      0

/dev/mmcblk1p2   partition    393272   97908      0

Depending on the performance of your microSD card, your N900 might now feel much faster when swapping takes place, about the same, or even slower - YMMV. My N900 definitely seems to have less those total I/O trashing episodes lasting 5-10 minutes, where you might think your N900 just died, after doing heavy I/O (e.g. download a 100 MB podcast with gPodder) after activating this dual-swap scheme.

Note: In my testing my N900 crashed when I tried to fill the VFAT data partition on the microSD with something like dd from /dev/null to a file. It's propably best to dedicate the whole microSD card for swap, if possible.

Credit To - Original Author Unknown

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

hi there....i've read this thread and i just cant get the microsd card to be a VR thing...

Care to help or just bring some light on this?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

That was a very helpful post, and the last sentence concerns me. I was planning on getting a large micro SDHC card to split up into VFAT, ext4 (for Easy Debian), and swap partitions. Now I wonder if that would be a stable combination.

Quote:

Originally Posted by izzuddinmeister (Post 932467)

Swap

...

Note: In my testing my N900 crashed when I tried to fill the VFAT data partition on the microSD with something like dd from /dev/null to a file. It's propably best to dedicate the whole microSD card for swap, if possible.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I've got an 8 GB mSD card split into 3 partitions between swap, ext3 and FAT32, out of necessity. No problems.

Based off of these instructions:
http://discussions.europe.nokia.com/.../751901#M17953

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Hi there

Trying to set up 1gb MMC for swap, having an issue:

sudo gainroot
mkswap /dev/mmcblk1p1
swapon /dev/mmcblk1p1

first to steps are fine, get an 'invalid argument' on step 3.

Any ideas?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

I had similar problems at first. You have to umount /media/mmc1 and then dd if=/dev/zero of=/dev/mmcblk1p1 bs=1024 count=1048576 before mkswap to ensure there are no holes. Also, have you set up the partition table for the MMC card?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Code:

    sfdisk -l /dev/mmcblk0 | /bin/busybox awk \

            -v home_opts="$home_opts" -v fat_opts="$fat_opts" \

        -f /usr/lib/genfstab.awk > $tmp_fstab

#BEGIN

    sfdisk -l /dev/mmcblk1 | /bin/busybox awk \

    '/\/dev\/mmc/ && $6 == 82 {printf "%s none swap sw 0 0\n", $1}' >> $tmp_fstab

#END

    cmp -s $tmp_fstab $fstab || cp $tmp_fstab $fstab

    rm -f $tmp_fstab



    if [ $ACT_DEAD -eq 0 ]; then

#BEGIN

      /bin/busybox awk '/swap/ {printf "/sbin/swapon -p 0 %s;",$1}' /etc/fstab | sh

      /bin/busybox grep dev /proc/swaps >/dev/null || echo "Failed to enable paging partition."

#END

      # Setup lowmem module

This is mi adeded script of rcS-late ....

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Quote:

In order to utilize both swap partitions to balance the I/O load (striping), they should have the same priority. The /bin/swapon command shipped with Maemo is the busybox version that does not support -p option. If you don't have Easy Debian environment installed, download the stock Debian mount package for the armel architecture and extract (-x) the swapon binary from it, and copy it somewhere e.g. /sbin/swapon.debian.

Where do i download the "stock Debian mount package for the armel architecture" so i can extract the swapon from it

or can anybody zip it and put it here to download?

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Quote:

Originally Posted by dr_frost_dk (Post 1031741)

Where do i download the "stock Debian mount package for the armel architecture" so i can extract the swapon from it

or can anybody zip it and put it here to download?

google for debian arm mount .deb. it is in repository of debian. i believe it is now also in the updated busybox in maemo repository.

i used to stripe but now i am exclusive on mmc for swap.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

hmm been trying different google and that.

can anybody point me to the site necessary or just upload the "swapon" & "swapoff" from the arm.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

mount is not separated from shell, so should be part of busybox or bash. Did you try busybox-power? This is an enhanced busybox shell which offers the -p switch for swapon.
However, i did not not test, if it is working.

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Quote:

Originally Posted by dr_frost_dk (Post 1031976)

hmm been trying different google and that.

can anybody point me to the site necessary or just upload the "swapon" & "swapoff" from the arm.

here you go. just use the swapon from this deb.

no need for swapoff from this package.

btw, thanks for giving the community awesome test for batteries. :)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Quote:

Originally Posted by mehulrajput (Post 1032229)

here you go. just use the swapon from this deb.

no need for swapoff from this package.

btw, thanks for giving the community awesome test for batteries. :)

Your welcome and thank you so much :)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

hmm got some missing libs etc...

but tried the busybox-POWER!!!! hehe and that worked just fine :)

Re: Using Micro SD Card as Virtual Ram on Nokia N900?

Quote:

Originally Posted by dr_frost_dk (Post 1032245)

hmm got some missing libs etc...

but tried the busybox-POWER!!!! hehe and that worked just fine :)

I didn't install busybox-power as I hate to fill up my rootfs. I want to move my files esp libs to emmc, last time I tried modest broke checking email so gave up.

apparently moving files from rootfs to emmc saves battery life. I am yet to confirm the same though :)