On 9/11/19 7:02 AM, Aaron Lu wrote: > Hi Tim & Julien, > > On Fri, Sep 06, 2019 at 11:30:20AM -0700, Tim Chen wrote: >> On 8/7/19 10:10 AM, Tim Chen wrote: >> >>> 3) Load balancing between CPU cores >>> ----------------------------------- >>> Say if one CPU core's sibling threads get forced idled >>> a lot as it has mostly incompatible tasks between the siblings, >>> moving the incompatible load to other cores and pulling >>> compatible load to the core could help CPU utilization. >>> >>> So just considering the load of a task is not enough during >>> load balancing, task compatibility also needs to be considered. >>> Peter has put in mechanisms to balance compatible tasks between >>> CPU thread siblings, but not across cores. >>> >>> Status: >>> I have not seen patches on this issue. This issue could lead to >>> large variance in workload performance based on your luck >>> in placing the workload among the cores. >>> >> >> I've made an attempt in the following two patches to address >> the load balancing of mismatched load between the siblings. >> >> It is applied on top of Aaron's patches: >> - sched: Fix incorrect rq tagged as forced idle >> - wrapper for cfs_rq->min_vruntime >> https://lore.kernel.org/lkml/20190725143127.GB992@aaronlu/ >> - core vruntime comparison >> https://lore.kernel.org/lkml/20190725143248.GC992@aaronlu/ > > So both of you are working on top of my 2 patches that deal with the > fairness issue, but I had the feeling Tim's alternative patches[1] are > simpler than mine and achieves the same result(after the force idle tag
I think Julien's result show that my patches did not do as well as your patches for fairness. Aubrey did some other testing with the same conclusion. So I think keeping the forced idle time balanced is not enough for maintaining fairness. Will love to see if my load balancing patches help for your workload. Tim > fix), so unless there is something I missed, I think we should go with > the simpler one? > > [1]: > https://lore.kernel.org/lkml/b7a83fcb-5c34-9794-5688-55c52697f...@linux.intel.com/ >
