Even though I made no changes to my desktop settings, the plasma theme cache in /var/tmp/cache... gets updated once after every boot. The files are not cleared on boot. The file being 80M large, I feel that it is slowing down KDE startup.

I am running opensuse 12.2 with kde 4.9.2 from the kde-release repo.

The cache's main purpose is to avoid re-rendering the theme's SVG files all the time (and that is expensive). I'm not sure on the specifics of the cache update, so I'll ask the Plasma developers.

If you simply logout and back in again is the Plasma theme cache updated?

Here's what I did -

back up the icon-cache.kcache ( 10M) and plasma_theme...kcache (80M) files. Reboot, login and compare the files with their backups - they differ.

Again backup the files as before, logout and login. Again, the files differ. So it appears that the files are updated on each login, not just the first one after a boot. Of course the subsequent logins are much faster because of the file cache in memory by the kernel. It must be noted that I only performed the actions mentioned and that I did not make ANY changes to the desktop settings- the icons, plasma, theme, style etc are all unchanged by me.

There is also a plasma-svgelements... file that does not seem to get updated as often and then there is ksycoca4 ( 2 MB) which is updated once per boot.

It seems counter-intuitive to cache file system files back on the file system and worse, then not use them afterward ! Even laptop hard drives have caches on them nowadays so it is probably unnecessary to maintain these caches which may have had their history at a time when hard drives were much slower- now they only make things worse.

I am a s/w developer and I once had a manager who thought it was a smart idea to cache DB data in the app server. This was within the last 5 years and the DB was oracle ! So, I guess he thinks we know better than all the people who work at oracle, about data caching. I don't think he really meant that and I never believed it anyway.

It is a cache, which will eventually throw out unused entries, so it has to update access times of entries even when you just read them.

cfeck wrote:It is a cache, which will eventually throw out unused entries, so it has to update access times of entries even when you just read them.

Thanks for the reply, Christopher. If it only updates the access time, why are the files different ? They have the same exact number of bytes but I cannot tell the difference - they are binary data.

Each .cache file contains multiple entries, so the access times need to be stored _in_ the file.