2016-12-08 - Potential memory leak issue on ARM base systems and resolution

Header Data

From: Glyn <bo***1@gmail.com>
Message Hash: c2c9279fd2b12cb7be86af24c2de4b81719e2eea89d3d5c9ad8838b69d53070d
Message ID: <dc22927e-7c65-404a-9e4c-0b8875d5a885@grasehotspot.org>
Reply To: N/A
UTC Datetime: 2016-12-08 09:18:00 UTC
Raw Date: Thu, 08 Dec 2016 08:18:00 -0800

Raw message 

Following on from my saga with the Raspberry Pi based system, one of the 
comments Tim made to me was that memory usage seemed a bit high at times, 
and recommended a /swap partition.  It had not actually become a problem 
because there had been an issue with staff accidentially switching the 
thing off every few days and therefore rebooting.

Swap files are not necessarily a good idea on a Pi as normally it would be 
running on an SD card. My setup however is using a USB disk drive and so I 
went and created a 2Gb file - the Pi has 1Gb of RAM.  Over the last week or 
so I have seen the swap file growing to a point where it reached 500Gb and 
on closer inspection it seemed most of the memory was being consumed by the 
irqbalance process.

irqbalance is used to balance interupt handling among multi-processors and 
so I guess with the ARM chip at the heart of the Pi being quad core is 
necessary so I investigated further.

My Google based findings are basically explained in this post:
https://bugs.launchpad.net/ubuntu/+source/irqbalance/+bug/1247107
and seem to suggest that the version in use with Ubuntu 14.04 running on 
ARM processors is suceptible to a memory leak.

There are two fixes:
Regularly restart the irqbalance service (*sudo service irqbalance 
restart). *I did this first and whilst it works; the usage goes down to 
about 4Mb and then grows - in my case up to 50Mb per day, I eventually 
opted for the second.
Upgrade the running version of irqbalance from the native 1.0.6 to 1.0.9 
(which is in later releases of Ubuntu but will not be added to 14.04) by 
means of a PPA helpfully created by one of the correspondents in the 
original post above. It can be found at https://launchpad.net/~futurepilot/+archive/ubuntu/raspberry-pi-2/ 


I am posting this as help to other users as the Raspberry Pi is proving to 
be a very good base for Grase Hotspot and so may be encountered by other 
usres.

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