Friday, August 21, 2015

Intel ATOM D525 Network Performance

I recently had the occasion to use a small Intel Atom D525 based Linux server to do some file transfers from one machine to another. I noticed that the file transfers were not very snappy, so I started to look closer at the issue. The Microtik switch that I'm using has a nice usage meter on each interface and I noticed that a single rsyc over ssh was only giving me 100-150Mb/s performance. Realizing that this was compressed and using the somewhat whimpy Atom CPU, I backed off to a minimal compression algorithm and ended up getting a modest improvement (200Mb/s). So, running 4 parallel rsyncs seemed to be the trick, but I seem to cap out around 5-600Mb/s:

The CPU seemed to hover around 40-50%, which was odd, I would have expected to see a higher percentage if my performance was capped.

I later tried NFS to see if that did the trick, but it too capped around 5-600Mb/s. The particular distribution of Linux I was using was Zentyal 3.5, but I also tried on an Ubuntu 14.04 Atom D525 system as well with the same results.

Just to make sure it wasn't something to do with the server I initiated a transfer from my desktop PC running Windows 7. You can see the server doesn't have any issues keeping up. In a later blog post I'll go into the ethernet switch I'm using and how changing the default queueing method affects performance in a positive manner.

The end result is that I wasn't able to push the Intel Atom D525 board beyond 5-600Mb/s. It could be an ethernet driver issue since the CPU didn't seem to be loaded beyond 50%, but I figured it would be an interesting datapoint to share. If anyone sees differently, please message me with your results.

Thursday, May 7, 2015

Android lockscreen image stuck?

I've been using a Samsung Galaxy S5 for about a year now. I don't really like it, and recently ran into another little annoyance that I'm fairly sure would *never* happen on an Apple device. I created an account and started listening to a book on my long commute to/from work. I notcied that Audible used the book image as the default lock screen image. Fine, whatever, but when Audible was closed the image remained. This was really annoying, as I couldn't change it even manually!

I googled for a fix, but nothing really came up that was useful. The suggestions mostly came in the form of "launch another streaming app and then lock the screen, that should undo it...". Well, that didn't work. Even when I closed all open apps it still didn't go away.

Then I discovered that even though I closed all the open apps it didn't really close. If I did the "pull-down" motion in touch-wiz there was an audible control applet still running. Once that control applet was closed, the problem went away. Very annoying, this is the lack of attention to detail that drives me nuts with Android. I'm likely going back to Apple just because I know it will do the right thing. It may not be quite as configurable, but the experience will be much more consistent.