Ubuntu's Linux Scheduler or Why Baloo Might be Slowing Your System in 14.04

Last month I posted about packaging and why it takes time. I commented that the Stable Release Update process could not be rushed because a regression is worse than a known bug. Then last week I was pointed to a problem where Baloo was causing a user's system to run slow. Baloo is the new indexer from KDE and will store all your files in a way you can easily search for them and was a faster replacement for Nepomuk. Baloo has been written to be as lightweight as these things can be using IONice, a feature of Linux which allows processes to say "this isn't very important let everyone else go first".

Except IONice wasn't working. Turns out Ubuntu changed the default Linux scheduler from CFQ to Deadline which doesn't support IONice. Kubuntu devs who had been looking at this for some time had already worked out how to change it back to the upstream defaults in our development version Utopic and in the backports packages we put on Launchpad. Last week we uploaded it as a proposed Stable Release Update and as expected the SRU team was sceptical. We should have been faster with the SRU which is our fault. They're there to be sceptical but the only change here is to go back to using upstream defaults. After much wondering why it was changed in the first place it seems that Unity was having problems with the CFQ scheduler and so it was changed, now we have suggestions that Baloo should be changed to adapt to that which is crazy. Nobody seems to have considered fixing Unity or that making the change in the scheduler in the first place would affect software outside of Unity. We tried taking the issue to the Ubuntu Technical Board but their meeting didn't happen this week.

So alas no fix in the immediate future, if it bothers you best use Kubuntu Backports. When someone on the SRU team is brave enough to approve it into -proposed we'll put out a call for testers and it'll get into -updates eventually. It's what happens when you have a large project like Ubuntu with many competing demands, but it would be nice if the expectation was on Unity to get fixed rather than on Kubuntu to deal with the bureaucracy to workaround their workarounds.