No Znx!

There seems to be a known issue which affects my Samsung Galaxy S and other Android based phones. Sometimes you will discover that the wireless is disconnected and it hasn’t reconnected automatically. Then when you go to the wireless settings (via Applications > Settings > Wireless and network > Wif-Fi settings) you will see the words “Error” under the Wi-Fi. Tapping to re-enable the wireless will instantly reconnect.

After a brief amount of time searching I found a rather good explanation via MIT. It turns out that if you are running a mixed wireless network at home (i.e. providing B, G and N types at the same time) you could find your phone sometimes disconnects in this way.

Foruntately the page also points out a possible solution; Wi-Fi Fixer which is also available via Marketplace and I do recommend donations!

This has left a little tool running in the background that detects the loss of wireless and sorts it out.

My wireless is now reconnecting automatically; Perfect!

I note that the recent update to Samsung Apps has moved the list into a more Marketplace style. Unfortunately they have somewhat hidden the tool and it isn’t obvious to find it (nor the updates!).

So the process is as follows:

Applications > Samsung Apps > Category > Utilities > Kies Air

To find your updates:

Applications > Samsung Apps > Menu Button (bottom left) > Downloads

Select and pick your updates.

Only thing that I’d like to see with Kies Air is general file management (i.e. to upload any file not just categories like Music/Images etc).

I am constantly reading some book or other and since I got a Kindle for an Christmas present (thanks Dad!); it’s got even easier to find new books and read them. I am however aware that not everyone reads and that some see a book as a hurdle rather than a joy.

If you find yourself in that state then I can suggest Quick Reads; a superb organisation that has got some amazing authors to write some sharp and quick reads to entice people into reading again.

I just got a bundle and will be reading my way through them!

I got myself a new phone recently and I can’t say anything bad about it at all; it’s a Samsung Galaxy S.

There are some awesome apps available for it; indeed I’m using a WordPress app to write this. But one app in particular has become a requirement for me.

The software that you can sync you phone is called Kies and it isn’t just bad; it’s awful. I found that it failed to work over USB initially until I managed to Google an answer. Next I attempted to set it up over Bluetooth; the phone happily paired and I was able to transfer manually but Kies similar gives a cryptic error (it says that the device denied the connection) at which point it then deletes the pairing.

There is salvation and it comes in the form of Kies Air. This app allows you to directly access you device via wirelesswith nothing more than a browser (and Java). The interface looks very much like Kies but actually works! The only thing you can’t do is upgrade the phone firmware but lets be honest that is infrequent anyway.

To get this software you must first allow non-marketplace apps to be installed:

Menu > Settings > Applications > Unknown Sources

Then open up the application called Samsung Apps:

Applications > Samsung Apps

There isn’t a search so you will need to scroll through and look for “Kies Air”. Once it installs to use it is simple enough.

Applications > Kies Air > Start

It will tell you a website to go to on your browser. Put that into your browser; you phone will ask if you wish to allow someone access so accept it. Then you will get the java application that looks and functions like Kies. Super!

As a side; I selected the Samsung Galaxy S over the Google Nexus S based on the fact that I can use the expansion slot. Lets hope that the SGS gets an Android update to 2.3 soon.

Every so often you see messages in your logs regarding ip_conntrack like the following:

ip_conntrack: table full, dropping packet

So my first thought it that it might relate to memory usage. Fortunately enough the kernel provides all the information we need to work it out. The kernel will allocate a “slab” when ever conntrack requires more memory, equally it will retain these slabs for a period of time and reuse if required. Each “slab” represents a number of pages of kernel memory, we can retrieve the current page size by using the following command:

# getconf PAGESIZE
4096

So each page is 4096 bytes. Next lets see how many slabs conntrack is using:

# grep conntrack /proc/slabinfo
ip_conntrack        6537  16620    384  984 1662    1 :  496  124

So that represents the following:

• ip_conntrack; a human readable name
• 6537; total number of objects in use.
• 16620; total available objects (including unused)
• 384; size of each object.
• 984; the number of slabs that are active
• 1662; the total number of slabs
• 1; the number of pages required to make a slab (normally 1)

The two other columns after the colon relate to SMP CPU information; we don’t need to discuss them.

So 6537 objects each of size 384 bytes, which means that we can fix around 10 per slab (4096/384=10.66). That means that the objects represent 2510208 bytes (~2.4Mb), but because of the overhead we are actually using 654 (6537/10=653.7) slabs or 2.6Mb (654*4096=2678784). So we are wasting around 256 bytes per slab (4096-384*10).

In other words an extremely small amount of memory. So it is very unlikely that is the cause. Further investigation reveal that it is normally due to the conntrack hitting the maximum count which can be viewed by looking at:

# cat /proc/sys/net/ipv4/ip_conntrack_max
65536

Comparing this to the current count:

#  wc -l ./proc/sys/net/ip_conntrack
   5602 /proc/net/ip_conntrack

We now know that it doesn’t use any great deal of memory at all, so we can easily double the count by doing the following:

# echo 131072 >/proc/sys/net/ipv4/ip_conntrack_max

Obviously in this example the memory usage was minor and there was little need to double the count but you can review your own system and increase as you wish now we know that it has a very small memory footprint.