On Wed, Jun 25, 2014 at 07:07:35AM +0200, Peter Zijlstra wrote: > Shall I merge this into patch 3?
Which gets me the below; which is has a wrong changelog. task_h_load() already computes the load as seen from the root group. effective_load() just does a better (and more expensive) job of computing the task movement implications of a move. So the total effect of this patch shouldn't be very big; regular load balancing also only uses task_h_load(), see move_tasks(). Now, we don't run with preemption disabled, don't run as often, etc.., so maybe we can indeed use the more expensive variant just fine, but does it really matter? --- Subject: sched,numa: use effective_load to balance NUMA loads From: Rik van Riel <r...@redhat.com> Date: Mon, 23 Jun 2014 11:46:14 -0400 When CONFIG_FAIR_GROUP_SCHED is enabled, the load that a task places on a CPU is determined by the group the task is in. This is conveniently calculated for us by effective_load(), which task_numa_compare should use. The active groups on the source and destination CPU can be different, so the calculation needs to be done separately for each CPU. Cc: mgor...@suse.de Cc: mi...@kernel.org Cc: chegu_vi...@hp.com Signed-off-by: Rik van Riel <r...@redhat.com> Signed-off-by: Peter Zijlstra <pet...@infradead.org> Link: http://lkml.kernel.org/r/1403538378-31571-3-git-send-email-r...@redhat.com --- kernel/sched/fair.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1151,6 +1151,7 @@ static void task_numa_compare(struct tas struct rq *src_rq = cpu_rq(env->src_cpu); struct rq *dst_rq = cpu_rq(env->dst_cpu); struct task_struct *cur; + struct task_group *tg; long src_load, dst_load; long load; long imp = (groupimp > 0) ? groupimp : taskimp; @@ -1225,14 +1226,21 @@ static void task_numa_compare(struct tas * In the overloaded case, try and keep the load balanced. */ balance: - load = task_h_load(env->p); - dst_load = env->dst_stats.load + load; - src_load = env->src_stats.load - load; + src_load = env->src_stats.load; + dst_load = env->dst_stats.load; + + /* Calculate the effect of moving env->p from src to dst. */ + load = env->p->se.load.weight; + tg = task_group(env->p); + src_load += effective_load(tg, env->src_cpu, -load, -load); + dst_load += effective_load(tg, env->dst_cpu, load, load); if (cur) { - load = task_h_load(cur); - dst_load -= load; - src_load += load; + /* Cur moves in the opposite direction. */ + load = cur->se.load.weight; + tg = task_group(cur); + src_load += effective_load(tg, env->src_cpu, load, load); + dst_load += effective_load(tg, env->dst_cpu, -load, -load); } if (load_too_imbalanced(src_load, dst_load, env))
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