On Wed, Nov 11, 2009 at 02:49:14PM -0800, Jonathan Adams wrote: > On Wed, Nov 11, 2009 at 02:11:07PM -0800, Scott Rotondo wrote: > > Garrett D'Amore wrote: > > >As far as this case goes, I'd better like to understand why we needed > > >a new class, instead of just using SYS. > > > > That's the key question, which I haven't really seen anyone address in > > this PSARC email thread. However, you can find a high-level answer in CR > > 6806882: > > > > "The basic issue is that the SYS scheduling class was not designed for > > long-running CPU intensive workloads. We introduce a new SDC (System > > Duty Cycle) scheduling class, which adjusts its threads' priority in > > order to give them a specified percentage of the processor. > > It also gives them a scheduling quantum, which gives other threads at > > the same priority on the same CPU a chance to run." > > That being said, I'm looking into just having this be another mode the SYS > class can run in, so that we don't pollute the namespace.
After investigating this and talking with Eric Saxe, we decided that this would only confuse things; the reason we have different scheduling classes is to classify the scheduling behavior. Making sysdc be just a mode of SYS would run counter to this. So we're leaving the case as written. Cheers, - jonathan
