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User Journal

Journal: Oh, look! An Atari Slashdot Logo With Scrolling Rainbows!

Journal by PotatoHead

Well, not too much to say right now, other than I like the changing logo. It's a Google wannabe kind of thing, but in a good way. Nicely done.

If you own and value old computers, particularly if you use them, feel free to chatter below. I have an Apple //e, Atari 800XL, and Color Computer 3, up running and useful. (well sort of useful)

Android

Journal: Android 4.0 ICS on ViewSonic G-Tablet using TeamDRH

Journal by rwa2
So VeganTab 7.1.0 (Android 2.3 Gingerbread) still appears to provide better app compatibility and performance, but it looks like the Android 4.0-based TeamDRH ROM is getting close in functionality!
I just installed the Beta 1.1 release, and it's making my G-Tablet run real nice. They ship with a 1.2 Ghz overclock option, and the Quadrant scores are better now, in between the Samsung Nexus and Samsung Galaxy. (The VeganTab ROM blew away both of them with a 1.4Ghz overclock).
Still a few issues I've reported:
  • Had to kill DSPManager to get audio working:
    mount -o remount,rw /system
    mv /system/app/DSPManager.apk /system/app/DSPManager.disabled
    reboot
  • Had to uninstall a bunch of background apps / widgets to free up enough RAM for everything to run smoothly. ICS really expects to have 1GB of RAM, so need to lose some weight to get good performance on 512MB :-/ Use an app like "OS Monitor" to see what's running and sort by memory usage.
  • My main goal is to get one of the full Linux distros installed in a chroot, but the TeamDRH kernel doesn't have loop block devices enabled.
  • A few apps don't run yet, like "Leo's RC Simulator", but I suspect they haven't ported to ICS yet.
  • ICS changed the way the internal sdcard can be shared with the PC, and I can't get the new way working :-P So now it's kinda a pain to transfer large files / backups.

But aside from that, I'm rocking out.

User Journal

Journal: Star Trek meets Candyland 5

Journal by grub

The other day my family was playing Candyland. Our daughter was getting into it so I started playing some classic Star Trek fight music.
The music ends just as she advances to GLORIOUS VICTORY!

YouTube video here

It's awesome, not that I'm biased... :)
User Journal

Journal: Running commands on many remote hosts using ssh and xargs 3

Journal by rwa2

There are a few different ways to run commands on groups or clusters of remote nodes, depending upon how complex the command.

Assuming your machines are named "node01" - "node10" :

# Run a command in parallel on all remote nodes
# results come back in random order as they are received.
pdsh â"w "node[01-22]" df

# pdsh allows some more complex listings of hosts
pdsh â"w "node04,node[06-09]" reboot

# Run a command sequentially on all remote nodes
# slow, but results come back in order
seq â"w 1 22 | xargs â"I '{}' ssh node'{}' df

# Run a command in parallel on all remote nodes without pdsh
seq â"w 1 22 | xargs â"P 22 â"I '{}' ssh node'{}' df

# Run a command in parallel needing pipes on the remote host
# Otherwise, pipes are processed locally
seq â"w 1 22 | xargs â"P 22 â"I '{}' ssh node'{}' \
"ps afx > \`hostname\`.txt"

# Run a command in parallel needing root
# sudo requires a tty, hence we pop up xterm windows
seq â"w 1 22 | xargs â"P 22 â"I '{}' xterm â"e \
"ssh -t node'{}' sudo gdm-restart"

# Run a command in parallel needing root and pipes on the remote host
seq â"w 1 22 | xargs â"P 22 â"I '{}' xterm â"e \
"ssh -t node'{}' sudo bash â"c \"echo 3 > /proc/sys/vm/drop_caches\""

User Journal

Journal: Using readahead to speed up disk loading times of any application

Journal by rwa2

Here's a way to get a list of files read by any application, so you can use readahead to preload those files optimally from disk:

CMD=firefox
strace -fe open $CMD 2>&1 | sed 's/.*open("\(.*\)".*/\1/' > $CMD.preload

# you can sift through that $CMD.preload file to look for things that don't belong

readahead $CMD.preload # preloads all those files into cache

time $CMD # should now start quite a bit faster, without much disk activity

## to clear disk cache as root (useful for testing / benchmarking)
echo 3 > /proc/sys/vm/drop_caches

If it works, you might want to append the contents of the .preload files for your commonly-used apps to /etc/readahead.d/default.later , so they are automatically loaded on startup (RAM size permitting)

User Journal

Journal: First troll defending Linux Desktop?

Journal by PotatoHead

Well shit. Never did I believe here on Slashdot, I would get a troll for a frank expression on Linux. Wonders abound it seems.

I've been in and around here for a very, very long time. The troll is actually funny. I won a bet on that one, BTW. Now I can go collect! Thanks for that.

I've thought about the state of open software off and on for many, many years. I think we've a clear case of a self-fulfilling reality happening with Linux Desktops. The current state of the computing industry mostly ignores the movers and shakers in favor of ordinary users doing what users do. Some of that happens on a Linux desktop, a lot of it doesn't, but does that mean the desktop is dead?

No! If you look out in the embedded space, just as one example, there is a TON of Linux. Most of those users run --wait for it! The Linux desktop! That kind of thing happens on a Linux system, just a safety tip from your buddy potatohead.

Now, maybe saying the word "fuck" got me the troll rating. Really? Come on folks! This isn't disneyland --or is it? You all tell me.

Finally, the core thing to remember about the growing body of open source software is all about the use value. For those who make the investment to make use of the open software tools, their use value and their skills are not mapped to closed things, and that value goes off the charts.

That's not gonna change for a percentage share metric published on some industry rag, filled with a lot of people, who don't actually understand the power of multi-user computing, nor the multi-user X window system for the powerful gift it is.

Those of us who do understand those things are not going anywhere! Why? Because we simply don't have to, and that's a fact often ignored when the failed comparison between Linux and proprietary software desktop solutions is invoked.

Think that one through kids. Think it through really hard, and maybe you may come to see how the open software dynamics work, and through that, why a pronouncement that the Linux Desktop is dead ends being as silly as I make it out to be. We users of that desktop will be perfectly happy to let you know when it's dead, k?

User Journal

Journal: Thanks for the gift subscription! 6

Journal by grub

I just received mail notification that a fellow user has bought me a gift subscription to slashdot. I'm already friends/fans with the person but his email address isn't visible so I can't thank the person off-/. (wimp, change your privacy settings and deal with the spam! :P )
 
Not sure what I did to deserve it, but I thank you!
 

User Journal

Journal: iPad pre-orders in Canada enabled, I drink the KoolAid 4

Journal by grub

Canadian pre-orders started today.

64 GB WiFi version ordered, should be here by May 28. No need for the 3G version, I can tether with MyWi on the iPhone.

My dad picked up the similar model on a trip to the US last week. Was playing with it on the weekend, awesome device. Perhaps not magical but still most impressive.

User Journal

Journal: tangoGPS - alternative to Google Maps Mobile on Linux devices

Journal by rwa2

So back when I had a Blackberry for work, the one app I really got addicted to was Google Maps Mobile. I basically stopped ever planning for travels. I would hop in the car or get off an airplane, think "now what?" and whip out the device and within a minute or two have directions to some place I've never been to before or a list of the nearest restaurants with a smattering of reviews.

Unfortunately, gmm only supports a handful of devices, most of which I'm not interested in. It won't install on my lousy Samsung t629 phone (which I hate, but Opera Mini helps me tolerate). I have a really old version of gmm on my Palm TX which works great, but doesn't support GPS. I almost bought a Nokia N900 to replace my various gadgets, but then I accidentally my old car and had to buy a new one, so took myself out of the preorder queue.

Which lead to my long protracted search for some kind of mobile mapping software for our eeePC 901 running eeebuntu. GPSdrive looked promising, but I couldn't quite get it to work with my iBT bluetooth GPS, or to even scroll out of Germany for that matter. Google Earth sort of worked, but the fonts and Z-buffer were wonky, and my previous experience hooking Google Earth Plus to a GPS wasn't actually all that stellar. I even tried running the Android SDK so I could try installing GMM in the emulator, and also installed androidx86, but alas, gmm wasn't an option in their stripped-down app repositories.

Finally after many google searches, I found tangogps while simply mucking around in aptitude. I was very impressed with both the simplicity of the user interface and the power of all of the features... In addition to supporting several different map sets out of the box (including an "for testing only" google satellite maps scraper), it also has a friend-finder database similar to Google Latitude, and better yet some of the trip meter features I missed from Garmin devices. Plus the inclusion of sources such as the opencyclemap db makes it more useful to me than GMM was. It's also possible to download tiles over a region in advance for offline viewing.

I now have my eeePC linked via bluetooth to both the iBT GPS and my Samsung t629 phone to download tiles from T-mobile's network using my $10/mo. web2go plan. Unfortunately, it doesn't support search yet, but does have rudimentary routing and directions. But it does give me just what I've really wanted -- an overhead moving map display.

Someday I hope Google will make GMM available for "real" computing devices, maybe on ChromeOS or Androidx86 or better yet just as a standard java app (yes, I also looked into installing the Sun Java micro development environment and generic phone emulator, but it looked like a real mess to get things installed and then somehow connected to a real GPS). Or at least porting to the Maemo platform so it would run on the N900 and friends. But barring that, I think I can make do with tangoGPS until I maybe succumb to one of the newer Android 2 devices due out this year.

User Journal

Journal: Palm T5 - TX touchscreen transplant

Journal by rwa2

I don't know why I hadn't thought of this sooner. My Palm TX had a pretty broken touchscreen, with large unresponsive areas in the middle of the screen and in the graffiti area. I had been coping with this for years... writing really small and frustrated graffiti in the corners, and creatively using various combinations of presses around the edges to activate buttons in the middle with touchscreen averaging.

But after replacing the broken screen in my wife's eeePC a few weeks ago (it was only $50 for a beautiful new glossy screen) I thought I might try buying a replacement Palm touchscreen (which go for about $20-$30 and include the special * screwdriver). Then I remembered that I had my old broken Palm T5 lying around, which still had a nice working touchscreen. I don't know why I assumed they wouldn't be compatible earlier...

Anyway, the small bit on my leatherman fits the Palm T* screws fine, and after a bit of drunken internal surgery, the transplant was complete. My Palm TX has a new lease on life, with a nicely calibrated touchscreen and hard buttons on the front that work consistently now.

Of course, now I have to invest in some better protective gear to keep it that way... my jacket pocket just contributes too much lint.

Unfortunately, the power button still doesn't work, but there are apps to compensate for that, like PowerBtn or OffStroke.

User Journal

Journal: Mirrored RAID read performance, where art thou?

Journal by rwa2

Back before mdadm (in the days of mkraid), the Linux RAID1 driver used to give you a performance boost when reading from a mirrored array. Essentially, from 2 mirrored disks, it would read half the data from each disk and give you the whole thing almost twice as fast. At some point, they decided to change that behavior so reads would only be performed from one drive at a time. There was still some small performance boost... it would decrease average seek latency a bit by reading from the hard disk spindle that was physically closer to the sector to be read. And maybe it allowed concurrent reads, so one process could read a file from one disk while another process read a file from the secondary disk... but for some reason, that doesn't seem to increase your overall throughput by anywhere close to a factor of 2... more like 1.3 from my brief testing (and I suspect most of that gain was probably due to disk cache rather than parallel reads).

But after reading a few different Linux RAID sites today, it looks like that you can get that kind of performance boost again out of mirrored arrays by using RAID10,f2 ( --profile far=2 )! And even though it's called RAID10, it even works on arrays as small at 2 disks. It basically works by striping your data across the first half of your drives, and then striping the mirror of that data across the second half. This appears to decrease write performance by about 5% compared to RAID1 or RAID10 near=2 (the default), but the read performance finally increases again not only due to striping, but also because your disk heads now stay near the faster outer rings of your disk drives, and only has to dive down to the inner rings for mirroring writes.

So I'm pretty excited about this since I've kinda been annoyed by it for the past few year. Except that of course I now have to rebuild all my RAID1 and RAID10 arrays to use the far=2 profile :P

Here are links to some of the more useful sites with data:
http://linux-raid.osdl.org/index.php/Performance
http://blog.jamponi.net/2007/12/some-raid10-performance-numbers.html
http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html

"Ahead warp factor 1" - Captain Kirk

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