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Friday, June 29, 2018

Solution: kswapd0 using 100% cpu

So I googled a lot about this problem without finding any proper solutions for this problem. Some suggested disabling swappiness (=how long should the computer wait before disposing memory to swap in stead of RAM). But this only delayed the problem with full cpu load.

I researched a bit more by my self. It looks like the problem is kswapd0 is unable to store anything at the SWAP memory. So I tried formating/restoring the SWAP partition. I use LVM, but the procedure is the same for those without LVM.

Do the following:
> su
Get root credentials
> cat /ets/fstab
Find out the location of your SWAP partition. It's either /dev/something or if you are using LVM it can look like /dev/mapper/SOMETHING--vg-SOMETHING_1. Next turn off swap:
> swapoff /dev/mapper/SOMETHING--vg-SOMETHING_1
Then check & format swap:
> mkswap -c -L swap /dev/mapper/SOMETHING--vg-SOMETHING_1
And enable swap again
> swapon /dev/mapper/SOMETHING--vg-SOMETHING_1

Monday, July 17, 2017

Quality Pry Bar Tool Set

Found this pry bar tool set which seemed to be of good quality. Very happy with it as it's strong and of perfect size. Highly recommended. Also, it's a lot cheaper then the US/UK alternatives which a lot of webshops are selling.

Wednesday, July 12, 2017

Ubuntu: Dropbox and crontab

In your default user, run "crontab -e", and add the following lines:

0 4 * * * DISPLAY=:0 /usr/bin/dropbox start >/dev/null 2>&1
0 5 * * * /usr/bin/dropbox stop >/dev/null 2>&1

This will start dropbox at 4am, and stop at 5am.

Friday, September 9, 2016

802.11ac wifi for Linux

Since I am running a HTPC in my living room I am dependent on having a reliable and FAST wifi connection. Running videos is one thing, but having a quick and responsive connection when it comes to fetching thumbnails for and browsing large photo files from my NAS is even more important.

Finding a good 802.11ac wifi adapter for my unit seemed to be harder then expected. Lot's of posts online told me that either 802.11ac simply won't work (you won't get your card to jump from 11n to 11ac speeds) and other challenges. Finding a pci card seemed to be even more challenging as most cards I could find with the best chipsets for Linux seemed to only be available on minipci express.

After some googling I did find that there were adapters for minipci express to pcie x1. I also did find one readily mounted with antennas, CE branded and at a reasonable price on ebay. The intel 8260AC is one of the latest chipsets running on 802.11ac offering a theretical speed up to 867 Mbps. The intel chipsets also offer good linux drivers. Installing the card was easy, the only thing I actually had to do was to make sure the iwlwifi package was installed, and to upgrade the kernel package of my Linux Ubuntu 14.04 distro, as the kernel package I was running used an older version of iwlwifi not offering support of the 8260 chipset yet. I took a full leap and went for kernel 4.4. After this everything wen't smoothly. No problems at all. The only thing is when I run iwconfig it says the card is running 802.11abgn but on 867Mbps. After some googling this seems to be a bug in the iwconfig app. The speed stated on iwconfig is the correct parameter to look at, and 867Mbps is impossible on 802.11n.

A word of advice: The ebay site selling this card states in large red letters and exclamation marks "This item don't compatible AMD computer motherboards". This is wrong. I have no idea why they say so. I knew this had to be wrong as there is a lot of AMD based computers running a intel wifi chip. I've had to deal with motherboard blacklists/whitelists before though. Anyhow, I am running this fine without any third party firmwares at all on a AMD motherboard running a AMD X3 450 CPU.

Thursday, September 8, 2016

Force unmount/umount of disconnected NFS drive in Linux

Following command as root: "umount.nfs4 /volume -f"

Thursday, April 7, 2016

Chromium in Debian: Flash missing - manual install of Pepperflash

So, here's the situation:
1.) Google Chrome dropped support of 32bit linux
2.) Pepperflash has gone missing from the Debian repositories
3.) Chromium only supports Pepperflash

Here's how you fix it:
1.) Install chromium.
2.) "apt-get purge" (not just remove) everything that has to do with flash.
3.) Download the latest available version of Google Chrome for 32bit so we can extract the plugin we need. Latest available version is google-chrome-stable_48.0.2564.116-1_i386.deb available here:
4.) Extract the file. Go to opt/google/chrome and find the PepperFlash directory. From this directory copy the to /usr/lib/chromium/plugins/ or any other available directory.
5.) For some reason I can't chromium to load the plugin by default. So I made a shortcut executable file with the following chromium prefix:
/usr/bin/chromium --ppapi-flash-path=/usr/lib/chromium/plugins/
6.) Run it. Enter "chrome://plugins/" into your address bar. It should now show up here.

Tuesday, October 27, 2015

IKEA Utrusta LED - remote problems

Installed the IKEA Utrusta LED system for my kitchen. The system have caused me quite a headache as I had a lot of problems with the lights randomly responding to the remote.

After a while I managed to sort out the problems. I did the following:
1.) First I got a new remote from IKEA. I'm not quite sure if this solved any problems or not, but I do think it helped quite a bit.
2.) Then I managed to identify one LED device which seemed to cause problems way more often then the others. I replaced this one. No more specific problem with this light.
3.a) My lights now worked all good until one night when I was downloading some huge files over the wireless network, when the lights went all hammock when using the remote. As I already know the Utrusta remote is using the 2.4ghz frequency - the same as my wifi, I went straight for the router and unplugged it. Suddenly it all worked perfect again.
3.b) To solve this problem I booted up my router again and changed wifi channel. I also have a router which runs on the 5ghz frequency. I was therefore able to change the wifi devices I have which use the most bandwidth to this frequency.

After taking these measures, I haven't had any problems for several weeks. The lights also respond way more synchronous then before. It's rather strange that IKEA doesn't seem to know about the frequency problems themselves. When I called them in the beginning this wasn't even mentioned, but after doing some research online it seems to be a rather normal problem with interference between devices running on the same frequency.

Update: 3 months later. Still no problems. All good! (FYI: The problem lasted me for 1-2 years until I managed to solve it.)