From: "Siddha, Suresh B" On a four package system with HT - HT load balancing optimizations were broken. For example, if two tasks end up running on two logical threads of one of the packages, scheduler is not able to pull one of the tasks to a completely idle package. In this scenario, for nice-0 tasks, imbalance calculated by scheduler will be 512 and find_busiest_queue() will return 0 (as each cpu's load is 1024 > imbalance and has only one task running). Similarly MC scheduler optimizations also get fixed with this patch. Signed-off-by: Suresh Siddha Signed-off-by: Andrew Morton --- kernel/sched.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/sched.c~sched-fix-broken-smt-mc-optimizations-with-cfs kernel/sched.c --- a/kernel/sched.c~sched-fix-broken-smt-mc-optimizations-with-cfs +++ a/kernel/sched.c @@ -2494,7 +2494,7 @@ group_next: * a think about bumping its value to force at least one task to be * moved */ - if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task/2) { + if (*imbalance < busiest_load_per_task) { unsigned long tmp, pwr_now, pwr_move; unsigned int imbn; _