TTY-based group scheduling [LWN.net]

TTY-based group scheduling

Posted Nov 18, 2010 19:20 UTC (Thu) by ccurtis (guest, #49713)
Parent article: TTY-based group scheduling

I'm fine with the tty-based approach personally, but it doesn't really seem ideal as more gui gets involved. Desktops - at the risk of portability - can integrate the feature, but what about another trigger?

I'm thinking of fork(): What about an approach like:

Add a field to compliment 'nice', such as 'penalty'.
Each time fork() is called, increment 'penalty' for the child.
If the task gets reparented to init(1), clear the penalty.
Schedule the task based on niceness + penalty.

This is just conceptual, of course. I imagine 'penalty' to be something like 1/10 or 1/8 of a 'nice', so the scheduler would use a value like (nice << 3 | penalty).

In the 'make + video' scenario, all the 'gcc' processes will have a penalty while the video will perform with higher priority. In the daemon scenario, they will be reparented and thus have their penalty cleared. I expect a 'renice' would also want to clear any penalties.

Now, this isn't the same as creating a cgroup automatically - but it does seem like the place to do this is within the shell. Or with a shell script as Lennart posted. But there may be another heuristic around fork() that makes more sense than simply the controlling tty.

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