Next PMSS version
We have now progressed into testing on fresh Debian 6, and only thing remains to be tested is Debian 5 upgrades.
This is a major upgrade on the backend, introducing new features for better user isolation giving us better control over per user resources.
This should stop people who greatly abuse the disk i/o in their tracks by simply not giving them time unless no one else is requesting that time. By default this is a per process thing, which doesn't work quite well, running I/O latency sky high even tho they should have equal or lesser priority than other processes. Add several of this kind of processes and you might have a server unresponsive even to SSH. It is a rare issue, but major nevertheless.
By this new version we are isolating users to their own I/O domains, not per process. We are also able to control the I/O weight on per user basis, meaning we can give higher priority to those with bigger packages directly, not just indirectly.
Overally this is going to be a stability release, and there is no significant user facing changes at all.
This is just a first step on a roadmap of major improvements on the PMSS system.
Friday, September 16, 2011
