I have a large home dir, because I use it for work and personal development, and there are hundreds of thousands of files.
I was wondering why Dolphin’s timeline was not showing the accessed files. I began to look around, and I found a way to get nepomukserver’s log.
First, enable debug output with kdebugdialog. Run it and enable debug for Nepomuk.
Then, restart nepomukserver from a terminal:
qdbus org.kde.NepomukServer /nepomukserver quit
Then, among all the output, I found a message that gave me a clue:
User limit reached. Please raise the inotify user watch limit
With this, I searched around and found how to increase that limit, in sysctl.conf
sudo sysctl fs.inotify.max_user_watches=<some random high number>
And for a more permanent solution, add that key to /etc/sysctl.conf
I picked 500000 because I have lots of files, and also 8GB of RAM, so memory shouldn’t be an issue. Default is 8k, packages for indexing servers usually increase it to 100k.
After this, I restarted Nepomuk, and files started showing in my Dolphin’s timeline. Yay!
For a final wrap-up, I disabled debug and restarted nepomukserver.
Disclosure: I’m not a Nepomuk expert, I’m just showing something that worked for me.