On Wed, Sep 11, 2019 at 09:19:02AM -0700, Tim Chen wrote: > 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.
Well, I have done following tests: 1 Julien's test script: https://paste.debian.net/plainh/834cf45c 2 start two tagged will-it-scale/page_fault1, see how each performs; 3 Aubrey's mysql test: https://github.com/aubreyli/coresched_bench.git They all show your patchset performs equally well...And consider what the patch does, I think they are really doing the same thing in different ways.