Issues with the scheduler in RHEL 2.6

Issues with the scheduler in RHEL 2.6

I recently upgraded to 2.6 kernels on various machines, and the following happens:

I go to 'rm -rf foo,' realize that the directory foo is HUGE (50+GB), hit ctr-z, and try to background it in an effort to move on with my life.

Under 2.4, the process would suspend immediately, background immediately, and the interactive response was perfect (IMHO).

Under 2.6, I hit ctr-z, and nothing happens for up to 30 seconds.

Eventually the process suspends, and then I can background it, but it's totally unnerving. It makes me feel like I'm using Windows.

Is this a real change in 2.6, or am I doing something wrong? Did the scheduler change between 2.4 and 2.6?

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Yes, there is a scheduler change between 2.4 and 2.6. While generally you will see improvements, in this case there is a known problem with some distros, though I haven't seen the problem with RHEL4. Rest assured, you are not the only one having problems. I suspect it has something to do with how your shell is not changing the nice value of the background job. Try using nohup to run your jobs in the background, and you will be in good shape; it's really a better practice than job suspension anyhow.

For more information:
Read Mark Hinkle's answer to this question, in which he explains how to change the process priority.

This was first published in June 2005