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This should perform better in particular > for single-threaded workloads and workloads that do not utilize all > cores (all the time anyway). > Capacity-aware scheduling wakeup works very different to the SMP path > used now, some workloads will benefit, some regress, it would be nice > to get some test results for these. > We already discussed DCPerf MediaWiki seems to benefit from > capacity-aware scheduling wakeup behavior, but others (most?) should > benefit from this series. > > I don't know if we can also be clever about ordering amongst SMT siblings. > That would be dependent on the uarch and I don't have a platform to > experiment with this though, so consider this series orthogonal to the > idle-core SMT considerations. > On platforms with SMT though asympacking makes a lot more sense than > capacity-aware scheduling, because arguing about capacity without > considering utilization of the sibling(s) (and the resulting potential > 'stolen' capacity we perceive) isn't theoretically sound. I did some early testing with this patch set. On Vera I'm getting much better performance that SD_ASYM_CPUCAPACITY of course (~1.5x avg speedup), mostly because we avoid using both SMT siblings. It's still not the same improvement that I get equalizing the capacity using the 5% threshold (~1.8x speedup). Of course I need to test with more workloads and I haven't tested it on Grace yet, to check if we're regressing something, but in general it seems functional. Now it depends if SD_ASYM_PACKING is the route we want to take or if we should start addressing SMT in SD_ASYM_CPUCAPACITY, as pointed by Vincent. In general I think I agree with Vincent, independently on this particular case, it'd be nice to start improving SD_ASYM_CPUCAPACITY to support SMT. Thanks, -Andrea