Support for SIGSTOP/SIGCONT in nice?

[Simon Josefsson]

This is a feature request for some non-essential functionality in
'nice'.  I understand if you think this is too uninteresting and/or
just add unnecessary code complexity.  Your thoughts on the idea are
appreciated in any case...

Frequently when I want to run a long-running I/O-bound job (i.e.,
rsync of the entire disk to a second disk) on a busy machine (i.e.,
mail and web server), the load increases to ~10 from a normal <1.
Using 'nice' doesn't help.  I don't know why this is, but I suspect
the kernel scheduler is sub-optimal for disk-bound jobs.

Would it be useful to consider extending nice so it can send SIGSTOP
and SIGCONT signals in configurable intervals?  Having rsync run for
30 seconds, sleep for 15, run for 30 seconds, etc, seem to avoid
slowing down the system to unusable levels.

I don't know what the syntax would be, but an 'advanced' interface
might be:

 nice --signal-length 45s --signal-pattern rrs foo

Which would mean to have 'foo' run for 30 seconds, sleep for 15
seconds, etc.

Comments?

Thanks.